September/October 1982 Volume 2, Number 5 $2.95 (USA) £1.50 (UK) The magazine for Sinclair users mssroo .aps and Mazes, Arithmetic, Solving Equations •Machine Language: Block Transfers • Hardware: Repeat Key • Games: House of Horrors, Space Taxi, Chase ROM-PAC APPLICATIONS HAS PROGRAMS ON PLUG-ON ROM CARTRIDGES FOR THE ZX-81 'EDUCATIONAL PROGRAMS 'APPLICATIONS GAMES Call or Write For Your Information Package Including: 'Current list of products and prices 'Operating instructions for all products 'Sample applications 'Adds you to our mailing list to receive new product news Updates on using the Sinclair with and without our products CALL 404-921 -4471 OR WRITE ROM-PAC APPLICATIONS 5921-AAIhambra Norcross, Georgia 30093 Due to possible trademark infringement Sinclair Applications is now operating under the name of Rom-Pac Applications. Neither Sinclair Applications nor Rom-Pac Applications has or have had any connections with Sinclair Research Ltd. SEEINGJS_BELII¥!Ng Shoot your way out of the asteroid Jejd Exclusive from Quicksilva 16K 14.95 Scramble between treacherous mountains and fearsome ahens 16K ThebestTS/ZXversionofthis classic game 16K "•« Chart your ups & downs 16K 14.95 Exclusive from Bug Byte. You won't believe this maze adventure, 16K 19.95 Exclusive from Paul HolmeslGK 14.95 Solve this adventure for a 10 000 pound sterling payoff 16X19.95 •Registered trademark of International Two great 2K programs 2K 14.95 Exclusive from Paul Holmes 16K 14.95 • Registered traaemdinu. ""*..- ^ — ^ ^— m^ ^^ Wk m MoSFfSIOOOTlXsTSOFTWARE FROM;,.. , Mi WK.-MI i-M v MY 10156 M/C & VISA ACCEPTED — B~48^, MUR RAY H.LLSTAT.ON -—N.Y. N.Y. 10156 (212)685-2080' WRITE A */ \ 4/\Y^ KAYDE Electronic Systems ZX80/1 ZX KEYBOARD WITH REPEAT KEY Fully cased keyboard $75.90 Uncased keyboard $55.90 Keyboard Case $21.90 This is a highly professional keyboard using executive buttons as found on top quality computers It has a repeat key and comes complete in its own luxury case This is a genuine professional keyboard and should not be confused with toy keyboards currently available on the market KAYDE 16K RAM PACKS The 16K RAMPACK simply plugs straight into the user port at the rear of your computer It is fully compatible with all accessories and needs no extra power and therefore it will run quite happily on your Sinclair power supply It does not over-heat and will not lose memory at all As you may know some makes go down to 11K after being on for a while This 16K RAMPACK is very stable and will not wobble or cause you to lose your programme It comes fully built and tested with a complete money-back Guarantee KAYDE FLEXIBLE RIBBON CONNECTOR Stops movement of RAM PACK and other accessories (Not needed with a KAYDE RAMPACK) KAYDE 4K GRAPHICS BOARD The KAYDE Graphics Board is probably our best accessory yet It fits neatly inside your ZX81 It comes complete with a preprogrammed 2K Graphics ROM This will give nearly 450 extra graphics and with the inverse makes a total of over ntne hundred The KAYDE Graphics Board has facilities for either 2K of RAM (for user definable graphics) 4K of ROM or our 4K Tool Kit Chips that will be available shortly All the graph.cs are completely software controlled, therefore they can be written into your programmes Here are a few examples A full set of •pace invaders — Puckman — Bullets, Bombs — Tanks — Laser Bases and Allen Ships NO EXTRA POWER NEEDED KAYDE 16K GRAPHICS BOARD SOFTWARE PECKMAN The only true ZX version of the popular arcade game Centipede: "In all I think this is the best presented moving graphics program I've yet seen Phil Garratt Interface SPACE INVADERS The best version available anywhere Graphics software can only be used with a graphics board KAYDE 16K 81 SOFTWARE Centipede "In all I think this is the best presented moving graphics program I ve uet seen Phil Garratt Interlace 3D/3D Labyrinth A Cubit Maze that has corridors which may go left, right, up down Peckman (the latest addition in 81 games) WHY WAIT TO PAY MORE — |— — — — — - FAST, IMMEDIATE DELIVERY Post to: Dept SY1 Kayde Electronic Systems Ltd The Conge Great Yarmouth Norfolk NR30 1PJ ENGLAND T*l: 0493 57867 (Dept. SY1) Please pay by international money order or certified cheque for immediate delivery. key $75-90 mch :ks f PImm tend me ZX I PlNNMndm* 16KRAMPACK& $59-90 each PImm tend me Flexible ribbon connectors $25-90 MCh PlMMMndmi 4K graphics boordt $59-90 MCh PIMM Mnd me 16K graphics board aoftwara $j 1-90 MCh PlMMMndme 16K 81 aoftwara $11.90 Mch I enclose . , Address _ Please add $5 p&p for all hardware and $2 for all software. Please make cheques payable to Kayde Electronic Systems Ltd The magazine for Sinclair users Mn September/October 1 982 Volume 2, Number 5 DEPARTMENTS 6 Letters • 8 Glitchoidz Report 1 2 SYNC Notes Grosjean 1 8 TRY This Klyver, Kluth, Laska 20 Just for Fun Dewhurst, Hampson 24 Perceptions Omstein The ZX Parser and the Operations Routines 88 Hardware Tips Chaiet MicroAce Hardware Peculiarities 92 Resources 96 Index to Advertisers SYNC IN THE CLASSROOM 29 List Learning with the ZX81 Hollandsworth A program for memorizing lists 34 Teaching with the ZX81 Deeson An overview of the British scene 42 Maps and the ZX80/81 Doakes Rethinking maps and mazes 50 How Many Blocks Kelly A program for preschoolers 54 Elimination Klyver Developing math and strategy skills 55 Arithmetic with a Smile Repicky A tool for elementary math drills 56 Arithmetic series Van Workum Developing math concepts through series 58 Solving Implicit Functions Wentworth Working with equations; algebra help 62 BOLEX: Beginners Ohms Law EXercises Stadta Help for general science and physics HARDWARE 66 Repeat Key Option Ingle Build your own repeat key MATH 68 Degrees, Grads, and Radians *- am Conversion programs 69 Rounding Off and Conditional Tests Stauffer Pythagorean triples MACHINE LANGUAGE 70 Block Transfers Scher Machine language programming technique GAMES 75 Chase Yu Pit your survival skills against the robot warriors 77 Space Taxi Dewhurst To the Spaceport, fast 80 House of Horrors Duchene One for Halloween 85 Mouthful Da Y Random wit and wisdom for your next party 90 8K ROM Updates Ahl, Horton, McGath, McLaugiin Nicomachus, Castle Doors, Widget, Hurkle REVIEWS 78 The Complete Sinclair ZX81 Basic Course Blechman Book review 79 ZX81 Chess vs. ZX Chess II Wren-Hilton Software review Staff Publisher/Editor-in-Chief Managing Editor Contributing Editor U.K. Correspondent Secretary Art Director Assistant Art Director Typesetters Financial Coordinator Personnel and Finance Circulation Advertising Sales Manager David H. Ahl Paul Grosjean David Omstein Martin Wren-Hilton Elizabeth Magin Susan Gend/.wil Diana Negri Rudio Karen Brown Renea Cole William L. Baumann Patricia Kennelly Frances Miskovich Carol Vita Jim Beioff tv*E MBE « (33 Volume 2, Number 5 SYNC (USPS: 585-490; ISSN: 0279-5701) is published bi-monthly by Ah! Computing, Inc., a subsidiary of Ziff-Davis Publishing Company. David Ahl, President; Elizabeth B. Staples, Vice-President; Selwyn Taubman, Treasurer; Bertram A. Abrams, Secretary. 39 E. Hanover Ave., Morris Plains, NJ 07950. Second class postage paid at New York, NY 10001 and at additional mailing offices. Subscription rates: USA: One year (6 issues), $16; two years (12 issues), $30; three years (18 issues), $42. Canada: $3 per year additional. Other foreign: $5 per year additional. For SYNC advertising information, contact Jim Beioff, SYNC Adver- tising Sales Manager, Ziff-Davis Publishing Company, One Park Ave., New York. NY 10016 (phone- 2 12/725-42 lb). All other correspondence should be addressed to: SYNC, 3v E. Hanovei Ave., Morris Plains, NJ 07950. In U.K., SYNC, 27 Andrew Close, Stoke Golding, Nuneaton CV13 6EL. Postmaster: Send address changes to SYNC, PO Box 789-M, Morristown, NJ 07960. Cover photo and other photos of the Sinclair computer and the children courtesy of Donna Compton. September/October 1982 data-assette® SOFTWARE and ZX81TIMEX 1000 SUPPLIES GAMES, EDUCATION, HOME OR BUSINESSS APPLICATIONS Choose from our Extensive collection of over 1 00 programs, far too many to list here so if you don't see something you like, send for our catalogue, $2.25 handling and — credit on your first purchase. GAMES MAZOGS A large complex maze which contains a glittering and fabulous treasure. You not only have to find the treasure and bring it out of the maze, but face the guardians of the maze in the form of fearful MAZOGS. Even if you survive you could starve to death if you get lost. 3 levels of difficulty, only $29.95 16K GALAXIONS Features of an arcade game. Attacks- Defends and keeps personal scores, only $14.95 1 6K BATTLE SHIP Play against the computer to destroy its battle ships, cruisers, destroyers, etc. only 70.95 16K VOLCANIC DUNGEON/HANGMAN 1 Attempt to rescue the elfin princess; mystical monsters, pits, fireyheavens. Reducing strength and water make the quest anything but easy 2. Deluxe version of the classic game, play against second person or computer with 400 word vocabulary, only $1025 16K ALIEN INTRUDER/HIEROGLYPHICS 1 You find you are the only survivor on the Explorer Class Mi star ship. Try and escape before you fall victim to the alien monstrosity that destroyed the crew. 2. Decode the ancient 39 symbol alphabet in time to save a famous explorer, only $10.25 16K WUMPUS ADVENTURE/MOVIE MOGUL 1.1-4 players seek the famous creature in the most famous and dangerous Wumpus hunt ever Features: Super Bats, Pits. Tremors, Swamps, Magic Arrows, Giant Sea Serpents, Wumpus Muk and Magic Springs. 2. Guide making you through the often hilarious traumas of production. Use your budget wisely to make a fortune, only $10.25 1 6K GREAT UNCLE ARBUTHNOT'S INHERITANCE You are left $100,000 but first must turn $100,000 of it into a further $1 00,000 by investing in the British Stock Market and Metal Exchange in 26 weeks. You then have a further 26 weeks to make $100,000 running a soft drink factory, only $70.25 16K GREAT BRITAIN LTD. You are the Prime Minister and Chancellor of the Exchequer of Great Britian. Your aim is to stay in office as long as possible. $10.25 1 6K AROUND EUROPE IN 80 HOURS You have a bet of $20,000 to visit 1 2 capital cities in Europe in two and a half days, travel agents permitting, only $70.25 16K HOME-SAVINGS FINANCE I Balance and maintain checkbook No overdrawn or returned checks, only $9 95 16K DATES Keep your diary in order only $8.50 16K HOME PLAN Keep track of your food and freezer needs, only $9.95 1 6K APPLICATION PROGRAMS TOOL KIT Provides many special features {line number, search and replace, free space, etc ) plus special graphics mode and tape routine. only $70 25 16K GRAPHICS TOOL KIT 22 exciting Machine code routines that give you control over your screen as never before only $70 25 16K MICRO-MUSIC Convert your keyboard into an organ mantle, only $8.50 1 6K EDUCATIONAL - Learn CHESS I Six levels and analysis options only $72.95 1K CHESS II Seven levels and a recommended move option, only $24.95 216K ZX-BUG 30 in 1 tool. Disassemble. Access all registers, search, modify memory with cassette routines, only $74.95 16K BUSINESS - Opportunity ZX-99 TEXT Fantastic word processor with output to your printer through our ZX-99. $29.95 16K BASIC BUSINESS I Cash flow control and planning $76.95 16K Coming in the next issue: HIGH RESOLUTION GRAPHICS BOARD AND COLOR All for your ZX-81 /Timex 1000 DEALERS WANTED/INQUIRIES WELCOME J* data-assette w 56 South 3rd Street, Oxford, PA 19363 Telephone Orders 1-800-523-2909 In Pennsylvania (215) 932-4807 data-assette ® in ZX81 or TIMEX 1 Your One Stop Shop All Products Guaranteed EVERYTHING YOU WILL NEED!! ADD ON TO YOUR ZX81 /TIMEX 1000!! ALL PRODUCTS 100% GUARANTEED!! NOW GROW YOUR SYSTEM AS YOUR NEEDS CHANGE, AND WE WILL GIVE YOU PRODUCTS, SERVICE, SOFTWARE AND ADVICE. WE HAVE BEEN IN THE BUSINESS IN ENGLAND FOR OVER ONE YEAR AND OFFER THIS EXPERIENCE TO ALL OUR CUSTOMERS. New Low Prices 1st STEP - MEMORY = RAM 16K-32Kor64K $59.95 - $109.95 or $149.95 Each RAM extends the BASIC memory to provide the user space for all applications. 2nd STEP - KEYBOARDS FULL SIZE or MINI $75.00 3rd STEP-ZX-99 $150.00 TAPE CONTROL Real Professional KEYBOARDS Computer Size and with special features like! ! ! ! Repeat Keys on the full size. Both units are easy to install at home. Supplied with cables & instructions. Now add Real "DATA-PROCESSING" power to your ZX-81 with our sophisticated extension. Provides "FULL SOFTWARE CON- TROL" of four (4) tape decks and a PRINTER interface for any RS 232 Serial Printer, giving full 132 ASC II characters of output. Plus!!!! 11 * ' AUTOMATIC "TAPE TO TAPE COPY" " * TAPE BLOCK SKIP. DIAGNOSTIC ASSISTANCE INTRODUCTORY OFFER "$375.00" Special to New Owners, show us your invoice and order in 30 days from the date. We will give you this "FULL PACKAGE" for the low price of $300.00. 64K RAM + ZX99. Add it to your printer and for under $400.00 you have full MINI-CAPABILITIES. ** DATA RETREIVAL WORD PROCESSING " RS 232 C Serial Printer Interface EQUALS REAL MINI-COMPUTER CAPABILITIES BLANK CASSETTES C- C- C- C- C- 5 10 12 15 20 C-25 $.69 $.74 $.77 $.79 $.84 $.89 Charge to: visa mastercard I account numbc l 1 Please rush me: ^S-T Quantity Pnct Total J L>fl"T fll'C Signature I | Date | NAME I ADDRESS . plus Shipping $4.95 ■ SHIPPING^ TOTAL Send me details: □ Software □ Supplies □ User Clubs □ Local Dealers □ New Products Hi-Resolution or Color Boards SYC-2 data-assette®56 South 3rd Street. Oxford, PA 19363 Telephone Orders 1-800-523-2909 In Pennsylvania (215) 932-4807 letter ROMs and RAMs Dear Editor: Could you please put more programs for the ZX80 with the 8K ROM in SYNC'! All I notice is programs mainly for the ZX80 with the original 4K ROM and the ZX81. Cris Rottjer RR #2, Box 86-A 500 E. Kendallville, IN 46755 Ed. See "ROMs and RAMs" in SYNC Notes in this issue. Memory Saving Tips Dear Editor: I want to call the attention of SYNC readers to the second paragraph on p. 129 of the 8K ROM manual: "A numerical constant in the program is followed by its binary form, using the character CHR$ 126 followed by five bytes for the number itself." This is a very inefficient way to store numbers. Dr. Ian Logan in SYNC 2:2 showed some good ways to get around this ineffi- ciency by using SGN PI and NOT PI for 1 and 0. He also used VAL "number" which saves three bytes. I suggest using one letter variables to hold numerical con- stants if you use the same constants more than once, or, if you use numbers that are more than four digits long. Declare these variables from the command mode so that they do not occupy program space. Another way to save memory is to use GOTO CODE "C" instead of GOTO VAL "40". A byte saved is a byte earned. This same technique could be used for any number between 10 and 255 even though 6 not all these characters can be accessed from the keyboard. Consider the follow- ing line: 500 LET N=N/100 You can accomplish the same thing with: 1 LET N=N/CODE "N" POKE 16520,100 After these lines are entered, line 1 will look like: 1 LET N=N/CODE "?" Now all you have to do is EDIT and renumber the line to 500. If you want to do several lines this way, type your pro- gram from the highest line number to the lowest so that the line you just typed will always be the first line in memory. John Coffey PO Box 448 Scottsburg, IN 47170 Dear Editor: Concerning Gary Chandler's "Alien Treasure" in SYNC 2:4, there are several ways to increase the efficiency and speed of the program. First, the four lines which check the bounds (132-135) can be deleted if logic is used: 89 LET I|=INKEY* 90 IF NOT 1*="" THEN PRINT RT 91 IF !* = "'* THEN GOTO 89 95 IF !$="©" THEN LET R*INT NO*2S) 98 IF I$="5- ) ie>0 if i$ = -e i) 110 IF I*«"6* 1) 120 IF I*='7' THEN LET B=B- 1 If the expression in parentheses is true, it has a value of one; otherwise the var- iable is not changed. Also, INKEYS could change between lines; therefore it is always best to assign INKEYS to a variable and then check it as in the example above. Second, lines 81-84 indicate which direction the monster is to move. This can best be done by using SGN. Delete lines 81 and 83, and then enter: 82LETX=X+SGN(A-X) 84 LET Y=Y+SGN(B-Y) SGN returns -1 if the expression in paren- theses is negative, 1, if positive, and otherwise. Then the variables XI and Yl can be deleted by deleting lines 7, 8, 86, and 87. Third, if the inspiration is great enough, the array can be deleted and a PEEK can be done to the screen location desired. Use LET S$=CHR$ PEEK (PEEK 16396+ 256 * PEEK 16397+33* R+C + l) where R is the row and C is the column. The character at that position is returned in S$. Michael Williams 1300 DePaul Way Virginia Beach, VA 23464 The SAVE Signal Dear Editor: A friend recently purchased Sinclair's 16K RAM pack, but found that the SAVE signal was drowned out by the extra noise it caused. After trying several types of filtering, I found two large foil tabs on the underside, one by the edge connector and the other next to the regulator. Connecting these with wire and rosin core solder reduced the resistance and the noise. Raymond Fowkes PO Box 336 Coalinga,CA93210 HJ SYNC Magazine Has Down Time Got You Down? MicroSync Has The Answer As Sinclair's Exclusive Authorized Service Center, we have the experience and expertise to keep your ZX product operating properly. WE OFFER Maintenance Agreements on Sinclair and Timex/Sinclair Products Reliable Low Cost Repairs Prompt Turnaround Sinclair Factory Replacement Parts A MICROSYNC MAINTENANCE AGREEMENT IS A VERY GOOD IDEA... Protect your Computer Investment With the Purchase of a MicroSync Maintenance Agreement. For a low cost yearly fee MicroSync will provide all parts and labor necessary to keep your computer operating properly. Our maintenance agreement also covers one-way shipping costs for all repairs. (You pay .only the cost of sending the unit to us.) You will have no unexpected repair bills or service worries during the period of maintenance agreement coverage. To Purchase a Maintenance Agreement Use the Coupon Below. Equipment Unit Price Qty. Total Maintenance ZX81/TS1000 14,95 Agreement 1 6K RAM/TS1 01 6 14.95 Purchase ZX Printer 16.95 if Unit is Less Than 90 Days Old. (Proof of Purchase is Required.) Maintenance ZX81/TS1000 34.95 Agreement 1 6K R AM/TS1 01 6 34.95 purcnase zx Pr|nter 39.95 If Unit is Over 90 Days Old. □ I Would Like to Purchase a MicroSync Maintenance Agreement. □ My check or money order is enclosed. I would like to pay by II Visa I ! MasterCard, My credit card # is . Its expiration date is . Signature i I I Would Like Additional Information. To: MicroSync Services, 162R Marlboro St., Keene, NH 03431 My Return Shipping Address is printed below. address, city . state . .zip. Total Enclosed $_ Phone ( ) . Pseudo-Giitchoidz From time to time readers call our attention to "Glitchoidz" they have met in entering programs. However, on closer examination we find that these are "pseudo-GlitchoidV because the problem is not in the listing. You can avoid these "pseudo-Glitchoidz" by paying close at- tention to the following suggestions: 1) Before starting to enter a program, note the ROM requirements as shown in the upper right or left corner of the first page of the article. A 4K ROM program is for a ZX80 or MicroAce; an 8K ROM program is for the upgraded ZX80 or MicroAce, the ZX81, and the Timex/ Sinclair 1000. You cannot enter a 4K ROM program on an 8K ROM machine or vice versa without translation. This seems to be the most common problem new users encounter. Wherever possible we give both listings. Usually 4K ROM programs can be translated to the 8K ROM, but the reverse is often difficult. 2) Pay careful attention to the RAM requirements before you start typing in the listing, 3) Read the article through carefully before attempting to enter the program. While we can sympathize with our readers' eagerness to try out the new programs, we remind everyone that the Qlirchoidz Report 1 programs are usually a part of a tutorial article and that the article contains nec- essary information about the program. 4) Enter the program as printed in the listing taking into account any directions given in the article. Be sure you know what the program is supposed to do. If the program does not run, assume first that an entry error has been made and double check your entry. All the 8K ROM programs which look like the listing for "List Learning with the ZX81" in this issue are direct printouts from our ZX81. The program was entered on it, tested (and found to work as the author indicated), and then printed out directly from the computer with no intermediate typing stage. This does not mean that the pro- gram has no bugs, but the listing printed did run without bugs during the time we tested it. Occasionally some characters are not as clear as we would like due to the reproduction process, but the com- puter will tell you if this results in a syntax error while some experimentation may help locate the correct entry in other ZXPRESS-- Non-Trivia! Solutions' new Integer Basic Compiler! Now you can write programs in rapid time! • compiles ZX-81 Basic source code to machine lan- guage: write and debug in a subset of ZX-81 Basic; com- pile when it's right • increases the speed of the ZX-81 20 to 50 times • 208 regular variables, 26 dimensioned variables; vari- ables are 16 bit two's complement integers • compiled code can be stored in REM or in 2000H to 3FFFH address segment, if available • the source code can be located anywhere and the posi- tion of the compiled code can be selected, allowing you to write a long program compile it in pieces, and link the pieces • 3 functions -PEEK RND, & USR • 14 key words • $29.95 Still available: • Letter Raiders & Life with Palette • challenging games • $9.95 each ZXPRESS Letter Raiders Life with Palette QUANTITY PRICE $2995 $9.95 $995 TOTAL □ Check enclosed Charge my i l Mastercharge ! Visa Card No. Exp. Date _ Signature MNTFIVIAL801LTIENS P.O. Box 2941 Amarillo. Texas 79105 (806) 376-5723 SYNC Magazine BEHIND EVERY GOOD SINCLAIR IS A MEMOPAK If you own a Timex-Sinclair 1000 or ZX81 computer, you should have a Memopak behind it. From increased memory to high resolution graphics, Memotech has a Memopak to boost your system's capabilities. Every Memopak peripheral comes in a black anodised aluminum case and is designed to fit together in "piggy back" fashion to enable you to continue to add on and still keep an integrated system look. Printer Interface -"^ s^ Memopak RAM High Resolution Graphics Order at no risk All Memotech products carry our 10 day money back guarantee. If you're not completely satisfied, return it in ten days and we will give you a full refund. And every Memotech product comes with a six month warrant)' Should anything be defective with your Memopak, return it to us and we will repair or replace it free of charge. Dealer inquiries welcome. To order any Memotech product call our toll-free number 800/662-0949 or use the order coupon. iMtiMU IU.n CORPORATION 7550 West Yale Avenue Denver, Colorado 80227 (303) 986-1516 TWX 910-320-2917 [coS 2JL Q Kg citai i Mail to: Memotech Corporation, 1 Code: SYCO-9-10 7550 West Yale Ave.. Denver. CO 80227 i *Price Qty. Total I 64KRAM $179 95 ! m MM 10995 | L6K KA\! ».95 1 Centronics Parallel Printer Interface 104 95 1 RS232 Printer Interface 139 95 1 High Resolution Graphics 144.95 [ Shipping and handling 495 $4.95 * All prices quoted in 1 S dollars Tax** ** Colorado residents please add sales tax □ Check D MasterCard □ Visa Total Exd. | Name [Address l5S State Zip 1 j Memopak 64K RAM The 64K RAM extends the memory of your Sinclair by 56K to a full 64K. It is directly addressable, user transparent, is neither switched nor paged and accepts such BASIC commands as 10 DIM A (9000). The Memopak 64K turns your Sinclair into a powerful computer suitable for business, recreational and educational use No additional power supply is required. Memopak 32K RAM The 32K RAM Memopak offers your Sinclair a full 32K of directly addressable RAM. Like the 64K Memopak, it is neither switched nor paged and enables you to execute sophisticated programs and store large data bases. It is also fully compatible with Sinclair's or Memotech's 16K RAM to give you a full 48K of RAM. Memopak 16K RAM The Memopak 16K RAM provides an economical way to increase the capabilities of your Sinclair. And at the same time, it enables you to continue to add on other features with its "piggy back 1 ' connectors. It is compatible with the Sinclair 16K or a second Memopak 16K or Memopak 32K to give 32K or 48K of RAM respectively. Memopak High Resolution Graphics The Memopak HRG contains a 2K EPROM monitor and is fully programmable for high resolution graphics. The HRG provides for up to 192 by 248 pixel resolution. Memopak Printer Interface The Memopak Centronics Parallel or RS232 Interface paks enable your Sinclair to use a wide range of compatible printers (major manufacturers' printers available through Memotech at significant savings). The resident software in the units gives the ASCII set of characters. Both Memopak printer interfaces provide lower case character capabilities. The RS232 Interface is also compatible with modems. New products coming soon Memotech will soon be introducing four new Sinclair compatible products: a high quality, direct connection keyboard, a digitizing tablet, a l6K EPROM and a disk drive. Watch for our future advertisements. SYNC Program Listings Readers should note the following conventions used in the program listings in this issue: The ROM and RAM requirements for running a given program are shown in the upper outer corner of the first page of an article. Observe these carefully. NEWL1NE and ENTER are used inter- changeably. A number may be followed by a letter to show the type: b for binary; d for decimal; h for hexadecimal. In PRINT statements: #: Enter a necessary space. A (32): Use the graphic character on the A key 32 times. The underline means get the graphic on the key given in the line by whatever way your machine uses to get the graphic. An overline means use the letter in inverse form, e.g., A. INPUT : An underlined word found on the keyboard should be entered from the keyboard, not spelled out. If the keyword will not enter, hit THEN, the keyword you want, backspace and delete THEN, continue entering the line. This memory saving technique may be disregarded if you have enough RAM. cases. The 4K ROM programs, however, are not direct printouts so there is the possibility of an error in these listings. 5) Do not attempt to make changes in a program which does work before you understand the program as written. Again, remember the author is trying to show you something. 6) Be sure you know whether a given word in the program is a keyword, that is, a word entered from the keyboard in one stroke, or a word that must be spelled letter by letter. If a keyword is used within the quotation marks in a print statement, it does not function as a command but as the word in its normal meaning. This is a memory saving technique which can be ignored if you have the additional memory. An Alternative Display Method. 2:3. Space Warp. 2:3. These programs are for machines with the 4K ROM. The problems reported by some readers stem from trying to enter these programs on the ZX81. So the solution is quite simple: Do not attempt to enter a 4K ROM program on an 8K ROM machine or vice versa. DEF. 2:4 Listing 3: Change line 110 to: 110DIMF$(5,17) The program will work in 2K. ZX Destroyer. 2:4, pp. 49-50. The author has called the following to our attention: 1) Both the 4K and 8K versions can run on as little as 2K RAM. 2) Figure 4: Line 150: Delete the set of quotation marks after the comma. 3) Figure 5: Line 20 could read PRINT "ZX DESTROYER". 4) Figure 6: 1 REM, 6th line down, last character. This is a U, not a W as it might appear. 5) Figure 8: Delete lines 10-35. Renumbering by a USR Routine. 2:3, p. 12. The author notes a minor correction and a possible problem. 1) The quotation marks between TAB and RND in both cases are inverse. 2) The E between V and 7 may have to be changed to 3 on some ROMs. The manual ZX81 BASIC Programming (1st ed., 1980) shows the same character for codes 7 and 135. The 135 is in error; it is the inverse of 7. EdrSoth E and 3 work on our ZX8L gj FLORIDA CREATIONS PRESENTS THE GREAT SOFTWARE SALE ( ZX81-1K) Christmas Party Package Home Financial Package ( 3 LISTINGS FOR $1 ) Music-Plays "Jingle Bells'' over a standard radio using tii© natural radio frequency interference of the ZX 81. No hardware modifications are required! Christmas Scrollnorizon- tally scrolls "Merry Christ- mas 11 across the screen with large letters. Christmas Tree^Automatic- ally draws and decorates a Christmas tree. **** ORDER NOW SALE ENDS SOON ^FLORIDA CREATIONS f SC2 f i>.0. Box ( 3 LISTINGS FOR $1 ) Mortgage Analysis-caicu- lates monthly payments for home or car loans. Return on a Bond Investment- Calculates the actual rate of return for bonds bought at other than face value. LRoA. Planner-calculates your I.R.A. retirement poss- ibilities. #*** INCLUDE SASE WITH ORDER #* 16422, Jacksonville f FL f 32216 #« 10 SYNC Magazine SINCLAIR/TIMEX USERS NOW SYNERGISTIC OFFERS YOU THE SMART T DESIGN CHOICE THE SYSTEM LOGIC KBD-I SMART™' KEYBOARD ENHANCEMENT FOR SINCLAIR/TIMEX COMPUTERS r ^r* ^*" JA ^^^^^^ .. A ^ Ai|*|dbl*l|* J- A J- — — ' ' A A AAA A A A A » — H „ A A A "A AAA. - — ' v- - - _ - SYSTEM LOGIC — KBD-1 The System Logic KBD-I Keyboard en- hancement offers Sinclair ZX-80, ZX81 and Timex TS-100 users an intelligent keyboard peripheral. A KBD-I allows an increase in user throughput by as much as 70% while re- ducing fatigue factor errors. Now enter data and programs quickly without having to 'hunt' for key contacts. Each key produces 'tactile' feedback in addition to employing right-and left-hand 'smart' shift keys. The KBD-I remains in the shifted mode with a single keystroke, while exiting from the shifted mode with a second (left or right!) keystroke entry. The KBD-I simplifies integrating your computer system into a professional or business application. The compact size of the KBD-I permits easy portability, its brushed aluminum black anodized cabi- net is a cautious blend of attractive design and the highest quality engineer- ing and manufacturing techniques. SMART ™ features Patent Pending . 'SMART™* shift function • Tactile feedback • 59 keys (with left and right shifts) • Standard (QWERTY) typewriter format • Silk screen labels compatible with Sinclair/Timex keyboard • Compact design • Rugged yet attractive black anodized aluminum cabinet • Simple installation • Custom engineered for Sinclair/Timex computers • Auto-repeat function (fast/slow modes) Contact resistance: 20Q @ 1 mA Contact rating: 1.0V/A Contact bounce: ^S.OmSec. Switch life: 5.0x1 6 operations typical Switch force: <9.0oz. Switch travel: .01 5 in. MAIL ORDER TO: SYNERGISTIC DESIGN P.O. BOX 41 1023 CHICAGO, ILLINOIS 60641 •Illinois residents include 6% sales tax. SYSTEM LOGIC KBD-I KEYBOARD PRICE $85.95* QTY. AMT. Shipping and handling (per unit) $ 4.95 $ 4.95 Money order or check TOTAL NAME. ADDRESS. CITY _STATE_ _ZIP_ sync nates SYNC in the Classroom In the wake of the recent federal budget cuts in education SYNC has been receiving inquiries from teachers and school administrators about the Sinclair computer. The question they ask most frequently concerns the Sinclair as an alternative to the larger popular computer systems. They are interested in the fact that for the price of one of the popular systems they can get several Sinclair computers with 16K RAM packs and provide hands-on experience to several students instead of just one. For the price of several large computers a whole class could be equipped with the Sinclair com- puter. So a school system even with sharp budgetary constraints does not have to cut back on basic computer literacy programs; it could even initiate such pro- grams. Paul Grosjean Another question they often ask con- cerns the availability of educational soft- ware. Since the ZX80 and ZX81 were introduced to the United Kingdom mar- ket some months before they were avail- able here, most of the educational soft- ware available is from U.K. sources. Some U.S. software suppliers have made arrangements to distribute U.K. software here. SYNC has received a number of articles which suggest some of the educational uses of the Sinclair computers, and we have gathered some of these for our theme section "SYNC in the Classroom." These articles deal with a variety of levels from pre-school up. Two major characteristics show up in the articles we have received, First, the main focus of most is math. Perhaps this is natural; after all, a computer does compute. We will be using some of these in future issues. Second, many articles use the computer as a substitute for a pencil and scratch paper. Certainly this is one use, and it is an important one where the computations are extremely lengthy and tedious. However, it seems hardly worth the trouble to load a tape to do something that a pencil and paper will do more quickly. Since such programs are not difficult to write, they tend to appear first. At the present the computer seems to be more of a novelty in the classroom than an integral tool in the learning process. There are three main obstacles to classroom computer use. First, the most serious obstacle is that we do not yet have enough teachers with computer training to use the computer as a teaching tool. It seems frequently that the com- puter is assigned to the math department which is expected to either have or get the expertise to use it. Like other equip- ment which requires some study and work to use the computer may be in danger of being relegated to the closet when the enthusiasm of the administration for getting on the computer bandwagon wears off. GAMES PACK Bear this for value 1 Five 16K programs Plus ftvo 1K programs 3-D Battle ALL ON ONE CASSETTE FOR ONLY $9.90 (€4 95) 'BATTLESHIPS & 'CRUISERS GAME (16K ZX81) First computer version of this popular game of strategy and tactics Both grids on view together Establish the position of your fleet then locate and destroy the computer s fleet Visual display shows hits and missi ■ running score ONLY $9.90 (€4 95l An Essential addition to your 16K RAM ZX8 1 TOOLKIT written by Paul Holmes I Provides the following additional facilities Line renumber you state starting number and increment value GOTO s and G0SUB s included m line renumber Search and List Searches for and lists every line containing specified character Search and replace changes every occurence of a character as you require Free space • tells you how many free bytes you have left SPECIAL GRAPHICS ROUTINES Hyper graphics mode graphics never seen on a ZX81 liefore Fill mis your screen instantly with your specked character Reverse changes each character on your screen to its video TAPE ROUTINE provides a system WAIT condition until a signal is received m the cassette e.r All these routines are written m machine code and together v IK of your precious RAM an incredible achievement" FOR 76K ONL Y $9 90 1 £4. 95 i ^GRAPHICS TOOLKIT tsterpie 22 exciting MACHINE CODE routines tha' . Draw Undraw draws or deletes your mulu character shape which is defined m a REM statement You may define as many different shapes as you like and draw or undraw each at will at whichever screen position you choose Foreground On/Off rse this to protect existing characters on your screen When on new shapes will appear to slide behind and re emerge from other shapes Border /Unborder Draws a border round the edges of your screen area Edit lines can be usen H Your border is protected when foreground is on Fill Fills any number of lines you specify, starting at any line you specify, by your chosen character Reverse Converts all characters to their inverse video, control as in FILL Print Position Controls UP. DOWN, LEFT. RIGHT alter you. next PRINT position m the direction indicated Editpnnt Moves nexi PRINT position 10 first edit line Scroll fa UPSCROIL. DOWNSCROLL, RIGHTSCROLL. LEFTSCROLL Sctoll your screen m the direction indicated (2X81_16K RAM ONLY! sntrol over your screen as nevei before' Onscreen Offscreen turns your screen on or oft Background On /Off Fills your screen by your specif'ed character When foreground is on existing ' ifi is unaffected and shapes will appear to pass m front of your background, without deleting n Search and Replace will search the screen for every occurrence of the 1 ■ *v and replace it with your new character Square draws a square or rectangle from your specified co ordmates All these routines are m machine code for SUPER FAST response 1 Simply load GRAPHICS TOOLKIT, which repositions itself at the end of your RAM and then your own program lor key in a new one), GRAPHICS TOOLKIT uses only . your RAM and that includes space to load the programmers TOOLKIT d> ALL FOR ONL Y $ 1 J 90 fC5. 95) This includes a cassette with 2 copies of the program, 2 copies of a demonstration program plus a comprehensive instruction booklet with examples N ARE APPiif.ABiF FOW Export INCLUDING AlRMAl PAYMENT MAY BE MAOf IN STEI >uR RANK OR YOUR OWN U Si MADE P .-,-.-. AARf DESPATCH NQPMAut I DAYS f ROM RECEIPT OF ORDER 1» WAYSIDE AVENUE. WORTHING, SUSSEX 8N13 3JU T.lephone (0903) 85691 THE EXPLORERS GUIDE TO THE ZX81 If you have ZX81 then you need this book (120 Pages). 1 K and 16K Programs. Games and Application. RAM and I/O Circuits. Programming Hints ROM Routines. $11 from: TIME DATA 3 - Waldon Road Califon, N.J. 07830 Enclosed Name Address City Check/M.O. State L Zip SYNC Magazine NEW! From Intercomputer A Full Line Of Business Education And Entertainment Software for your ZX81 or Timex Sinclair 1 000 Please send me a FREE Program and Catalog Name A -J -I /AUUIt?J>£> Send this coupon to: Intercomputer Box 90 Prudential Center Boston, MA 02199 PLOT UNPLQT REM RUN RAND RETURN UT POKE PRINT HH C § GB CI 1 EH OH CHOI *tN COS TAN INT RND STRS CHRS COOL PEEK i/*B NEW SAVE DIM '-OR GOTO GOSUB LOAD LIST LET ^^^^^ flB H3 API 03 Kfi CH IB IS OR HH ARCSIN ARCCOS ARCTAN SGN ABS SOR VAL LEN USR COPy CLEAR CONT CLS SCROLL NEXT PAUSE BREA* SHIFT \z Ix Ic IvIbIn Im 1 1 SPACE EXP AT IN KEY$ NOT H Introducing the Sinclair ZX81. If you're ever going to buy a personal computer, now is the time to do it. The Sinclair ZX81 is the most powerful, yet easy-to-use computer ever offered for any- where near the price: only $99.95* completely assembled. Don't let the price fool you. The ZX81 has just about everything you could ask for in a per- sonal computer. A breakthrough in personal computers. The ZX81 is a major advance over the origi- nal Sinclair ZX80-the first personal computer to break the price barrier at $200. In fact, the ZX81 's 8K extended BASIC offers features found only on computers costing two or three times as much. Just look at what you get: ■ Continuous display, including moving graphics Sinclair technology is also available in Timex/Sinclair computers under a license from Sinclair Research Ltd. THE$9a95 ■ Multi-dimensional string and numerical arrays ■ Mathematical and scien- tific functions accurate to 8 decimal places ■ Unique one-touch entry of key words like PRINT, RUN and LIST ■ Automatic syntax error - detection and easy editing 1 ■ Randomize function useful for both games and serious applications ■ 1 K of memory expandable to 16K ■ A comprehensive programming guide and operating manual The ZX81 is also very convenient to use. It hooks up to any television set to produce a clear 32-column by 24-line display. It comes with a comprehensive programming guide and oper- ating manual designed for both beginners and experienced computer users. And you can use a regular cassette recorder to store and recall programs by name. Order at no risk.** Well give you 10 days to try out the ZX81. If you're not completely satisfied Just return it to Sinclair Research and we'll give you a full refund. And if you have a problem with your ZX81, send it to Sinclair Research within 90 days and we'll repair or replace it at no charge. Introducing the ZX81 kit. If you really want to save money, and you enjoy building electronic kits, you can order the ZX81 in kit form for the incredible price of just $79.95.* It's the same, full-featured computer, only you put it together yourself. Well send com- plete, easy-to-follow instructions on how you can assemble your ZX81 in just a few hours. All you have to supply is the soldering iron. A leader in microelectronics. The ZX81 represents the latest technology in microelectronics. More than 10,000 are sold every week. In fact, the ZX81 is the fastest selling personal computer in the world. We urge you to place your order for the ZX81 today. To order. To order, simply call toll free. Or use the coupon below. Remember, you can try it for 10 days at no risk.** The sooner you order, the sooner you can start enjoying your own computer. Call toll free 800-543-3000. Ask for operator #509. In Ohio call: 800-582-1364; in Canada call: 513-729-4300. Ask for operator #509. Phones open 24 hours a day, 7 days a week. Have your MasterCard or VISA ready. Address. These numbers are for orders only If you just want information, please write: Sinclair Research Ltd., 2 Sinclair Plaza, Nashua, NH 03061 . • Plus shipping and handling. Price includes connectors for TV and cassette, AC adaptor, and FREE manual. ••Does not apply to ZX81 kits. NEW SOFTWARE: Sinclair has published pre-recorded pro- grams on cassettes for your ZX81. We're constantly coming out with new programs, so we'l send you our latest software catalog with your computer. 16K MEMORY MODULE: Like any powerful, full fledged com- puter, the ZX81 is expandable. Sinclair's 16K memory module plugs right onto the back of your ZX81 . Cost is $49.95, plus shipping and handling. To order call toll free: 800-543-3000 Ad Code 09SYOS Price* Qty. Amount ZX81 $99.95 ZX81 Kit 79.95 16K Memory Module 49.95 Shipping and Handling 4.95 $4.95 TOTAL MAIL TO: Sinclair Research Ltd., One Sinclair Plaza, Nashua, NH 03061 . Second, some teachers are afraid of it and will resist its use. This is partly because some students are already far ahead of them in computer mastery, and we adults have a hard time accepting the fact that an elementary school student can know more than we do about a subject that everyone knows is difficult to master. Third, some schools restrict the use of their computers to advanced students. This is unfortunate because the idea is encouraged that computers are only for "special" students, not for "ordinary" students. Above all, the computer is not integrated into the total school curriculum as a tool with a contribution for each area. The serious use of the computer in education depends upon having teachers trained to use it in their particular fields, software exploiting the computer's cap- ability for interaction with the student, and an openness to a new tool for teach- ing and learning. How is the computer being used in your local school system? ROMs and RAMs Readers have requested that we publish 8K ROM translations of the programs we published before the 8K ROM was intro- duced. We are including some of these translation in "8K ROM Updates" else- were in this issue. We have also been asked to publish programs for the ZX80 with the 8K ROM. We specify the ROM and RAM require- ments on all programs and articles where these are necessary, but we do not specify the machine as such. The 4K ROM programs will work on the ZX80 and the MicroAce; The 8K ROM programs, on the ZX81 and the ZX80 with the 8K ROM. However, since the SLOW mode cannot be accessed on the ZX80 with the 8K ROM, programs which must be run in SLOW mode require some slight modification. The SLOW mode functions to allow the viewer to see the display change. Usually the action graphics routines have two basic parts: 1) putting a new picture on the screen, and 2) taking it off. On the ZX80 with the 8K ROM you can use a PAUSE between these two parts to allow you to see the change. For example, 10LETJ=1 20 LET 1=1 30 PLOT I,J 40 UNPLOT I J 50LETJ=J+1 60 GOTO 30 Initialize variables "Prints" picture Removes picture Adjusts variables for new picture Loop back to "print" new picture For the ZX80 with the 8K ROM you would add 35 PAUSE (number, e.g., 10) The number determines the length of the PAUSE. In the U.S. 60 equals one second; in the U.K. 50 equals one second. Generally our authors write their pro- grams on one specific machine. We request our authors to supply the listings or modifications necessary for the users of the other ROMs and machines; on occasion we modify or translate a pro- gram. The ROM in parentheses indicates such a translation or adaptation. Since 8K ROM programs are virtually identical we have not made separate listings for the ZX80 users. Some readers have also asked concern- ing the RAM designations. These RAM designations (usually in the upper right or left corner of the first page of an article) do not refer to the length of the program, but to the amount of RAM your machine must have to run the program. Many programs designated 16K require much less than 16K RAM, but, since most users and authors have IK, 2K or 16K RAM, we do not specify intermediate RAM levels. When a RAM designation appears in parentheses, we mean that modifica- tions of the basic program are provided for use with that much RAM. "fl Get on the Control Bus for only $49. 95 TS? • • • and be on TIME. 8 lines departing (outputs capable of driving relays) 8 lines arriving (T T L compatible inputs] With our real Time Clock and Calendar Compatible with ZX80/81 MicroAce & TIMEX 1000 All accessories can be connected together and separately controlled from the I/O parts TIME MONTH DATE YEAR DAY OF WEEK 99 23:59:59 12 - 31~ e Leap year correction • 12/24 hour format • ± 30 second time correction (hardware or aoftware] • Bsttery back-up circuit Comes complete with: • All software needed to operate clock and Input/Output ports • Dn board 5 volt regulator. • Feed through Sinclair Bus connector to allow normal expansion. • Each port is expandable through Multiplexing. • I/O ports and other controls mate with Radio Shack" 44 pm edge socket. • 90 day Warranty Accessories used with I/O Board: • A to D and D to A converter • Wireless control system compatible with BSFT modules • Solid state 25 amp switch modules • B SPDT 5 amp relay card Future products ussd with I/O board: • Touch Tone" encoder/decoder and other telephone products • Speech synthesizer • Sound synthesizer Model Description 31D 315 320 325 330 340 350 31 7 Price I/O port with real time clock fe«Mt «nd tutid] PC board and manual of #31 O A to D and D to A converter (Built and tested) Bare A to D and D to A board and manuai Wireless control system (Built and tested) Solid State'* AC SWItCh (Built end teeted] Relay board (Built end tested] Clock IC and crystal (Teeted) Shipping and handling S49.95 S24.95 £39.95 $13.95 $44.95 $19.95 $69.95 $15.95 $ 3.95 Orders accepted by phone or mail. For mail orders, send check or money order Foreign orders must be in U.S. currency. California residents add 6<=Hd tax write for free catalog P.O. Box 3295 Eacondido, CA 92025-0580 Information (714) 741-5132 24 HOUR ORDER LINE NAT 800-227-1617 Calif. Res 800-772-3545 Aak for operator 367 Make Your Sinclair Wwk Harder, Belter... with quality, affordable and dependable peripherals from CAI. The Interface The CAI/ O Board® plugs into the computer's expansion port and is the interface that lets your computer communicate with the outside world. There is a serial RS-232 compatible 1/ O port, 3 parallel 1/ O ports used to design circuits to control home lights, power relays and additional ports to accept printer, mass storage device and memory expansion. $7Q95 $4 f -A when purchased separately >f\Q 95 W^when purchased with CAI peripherals The Printer New! The CAI/ P40 prints the complete library of regular and inverse alpha-numerics and graphics in 40-column width. Three user- addressable modes print in regular or enhanced (double type size): List program from memory, print text or data from program, print screen $ "t ^fC\Q^ complete stand alone printer, (can 139 5 be upgraded to use with other CAI peripherals) $ "I "I 095 re 3 u ' res CAI/0 Board for complete \^f compatibility with other CAI peripherals Mass Storage Device CAI introduces the Stringy Floppy® for the Sinclair or Timex Sinclair. It has the speed of a disc drive at a fraction of the price. Data is stored on an inexpensive continuous loop magnetic tape cassette. This device inputs and outputs data at an incredible 1 4 , 000 baud- - 56 times faster than Sinclair cassette recorder interface. The system is designed to accommodate two Stringy Floppy drives for even more versatility. $1QQ95 rer < Requires CAI/O Board Computer Network Package This package consists of ASCII conversion program, phone modem, connecting cable. Now you can communicate with large main frame computers, mieroand mini-computers and computer networking systems (The Source®). $1/1,095 Note: Order this package when $Q95 $795 Stocks $Q95 Wiz Bang Zf Math $2495 ordering your CAI/O Board, for ASCII conversion program only Additional Peripherals Memopak® 64K memory expansion $ 159 95 Programs: $1A95 Home Jjf Finance Bio Rhythms Why buy from CAI? All CAI peripherals come with complete instruction manuals, schematics and a 30'day unconditional replacement warranty. Each works with either the Sinclair ZX-80, ZX-81, MicroAce and Timex/ Sinclair 1000. Our technicians are happy to answer your questions before and after purchase. $Q95 Math Z7 Tutorial I I ■■1 llllr InIIBIIIII CAI Instruments, Inc. P.O. Box 2032 Midland, MI 48640 4:30 p. n 8:30 p.m. Phone: (517) 687-7343 Office Hours: 9:00 a.m Evening Hours (Technical Information) 6:00 p.m Orders accepted by phone or mail. For mail orders, send check, money order, VISA or MASTERCARD numbers. Foreign orders must be made in U.S. currency. Quantity Description Unit Price Total CAI/O Board (See Price) CAI Printer (See Price) Stringy Floppy $109.95 Other SUBTOTAL Shipping and Handling 4% Sales Tax (Michigan Resident Only) TOTAL I I D Literature, enclose $1.00 SHIPPING AND HANDLING CHARGES Within U.S. $5.00 Outside U.S. — F.O.B. Midland, MI MasterCard/ Visa Exp. Date Name Address City State Phone No. . Zip CAI/ P40 Printer m€nOPRH64h I 1 'I '1 1 ,'1,1,1,1 CAI/O Board ^ »► gga ^ *S| fife Stringy Floppy V 8K ROM; IK RAM 4K ROM; IK RAM tru thi 4KROM Enter the following program, 10 FOR A =38 TO 63 20 FOR B=38 TO 63 30FORC=38TO63 40 PRINT CHR$(A);CHR$(B);CHR$< C);"#"; 50 NEXT C 60 NEXT B 70 NEXT A Hit RUN and NEWLINE. When the screen is full, press NEWLINE, CONTINUE, and NEWLINE. Repeat this process until you have completed the sequence. The same program can be entered on the 8K ROM, and you might want to add the line: 45 SCROLL. Our thanks to: A. Dan Klyver 29 Old Stagecoach Rd. Weston, CT 06883 8KROM Enter the following program. For the graphics, use the graphic on the key indicated the number of times in (): 10E(1),7(10),R(1). 20 5(1), 10 spaces, 8(1). 30W(1) V 6(10),Q(1). 50 10 spaces, A$, 10 spaces. 1© PRINT RT S, 10; "^" 20 PRINT RT 10,10;"| 30 PRINT RT 11,10; 4.0 INPUT R* 50 LET R»=" + R* + " 60 LET B=LEN CR$) -10 70 FOR X=l TO B SO PRINT RT 10,ll;R$(X TO X+SM 90 NEXT X 100 GOTO 70 Be sure that you are in SLOW mode, hit RUN and ENTER. After the display appears, type in your name and press ENTER. Observe the results. Our thanks to: Mark Kluth 143 Humphrey Circle Shawano, WI 54166 Enter the following program very care- fully. Any underlined letters indicate that you should use the graphics on that key. The underlined tokens and keywords should be entered directly from the key- board and not spelled out. If a given keyboard entry will not enter, hit THEN, the keyword, backspace and delete THEN, go forward again and continue typing in the program. 10 REM <>E£RND1£//<>DT3<>Q#0<> FAST VAL 1 1#LN P?AT _<> LPRINT <> Q##<>7( CONT T3<>Q//0<^ FAST VAL 11//LN P?AT <> LPRINT <>Q##<>F( C ONT / ASN 20 PRINT AT 11,31;"#" 30 LET S=USR 16514 After entry is complete, SAVE on cassette. Then be sure that you are in FAST mode, press RUN and ENTER and watch what happens. Our thanks to: Scott Laska 2205 Calumet Dr. New Holstein, WI 53061 J 16K INSIDE?!! /K < No Bulky Add-ons! Leaves back connector free for printer or peripherals! Inexpensive using your parts Can be assembled and installed by anyone who can use a soldering pen. Complete instructions, including schematic, parts list, suggested Board layout, assembly and instal- lation. $7.95 With optional pre-made P.C. Board, ready for assembly. $18.95 from: Independence Research P.O. Box 1497 Orem, Utah 84057 PROGRAM FASTER! Now you can write and revise program listings faster than ever before. Never again count spaces for PRINT, PRINT AT, and PLOT functions. ROMARK SCREEN PADS are a larger, improved version of the ZX Basic Hand Book (page 89) showing line, column, and pixel numbers. We use heavy eraseable paper, 50 sheets per pad. FIVE SCREEN PADS (250 Sheets) $7.95 Shipping and Handling 1.50 Send S.A.S.E, for information on math programs, Leadfoot " anchor pads, and "Solid Jack sockets. ROMARK INDUSTRIES, INC. 20412-29 CENTER RIDGE RD. CLEVELAND, OHIO 441 16 18 SYNC Magazine / Now available in the U.S. at the incredible price ot only $119.95 (£62.95) ACTUAL SIZE 3" x 2" THE 64K RAM PACK Fully built, tested and guaranteed. No additional power supply required. Black plastic case no larger than 16K RAM PACK. No wobble problems Fully compatible with printer etc. The use of this memory is as follows: - - 8K Sinclair ROM 8 - 16K RAM that is unaffected by NEW, LOAD, SAVE and can be used for storing machine code routines. 16 - 32K BASIC Code, Display file, Variables, Machine Code 32 - 64K Variables 16K RAM PACK at only $49.95 (£29.95) including FREE ALIEN ATTACK (7K -Ml code) - value $11.00 (£5.75) As reviewed in 'Your Computer' - (March 1982) the leading U.K. Sinclair Publication. Almost 10.000 units sold in the U.K. so far. THE NO FRILLS' ECOIMO TECH 16K RAM PACK ONLY $39.95 (£20.95) We believe the Econo Tech is the lowest priced 16K RAM available anywhere. No frills - just a reliable and economical way to expand your 7X81 As reviewed in 'ZX Computing' August/Sept 1982, the new U.K. ZX computer publication. Available ONLY from JRS. PLEASE NOTE All i Payment may bi RS SOFTWARE ^T f I r i i i / _ m ■ i 19 WAYSIDE AVENUE, WORTHING. SUSSEX. BN13 3 JU Telephone: (0903) 65691 8K ROM IK RAM Just pur Fun Generally SYNC prefers articles in some depth to help you get more out of your computer. However, we receive many short programs that illustrate a point, demonstrate a technique, or show some- thing the reader has found interesting. "Just for Fun" shares these programs with you. If you learn something, great. If you have some fun, great. If you have some that you want to share, send them to: Just for Fun, SYNC, 39 E. Hanover Ave., Morris Plains, NJ 07950. Zap M. Hampson You are a laser zapper on a space cruiser on routine patrol when suddenly your ship is under attack. Each of the attackers is assigned a number, and each zapper is assigned a target. A target number appears on your screen, and you must destroy that target and only that one. Your performance as a zapper is measured by the score you achieve. Each assigned target hit is worth one point. Your rating as a zapper is the score you achieve. The higher the score, the higher your rating will be. If you shoot at a target you have not been assigned, you get no points. Furthermore, you will have wasted a shot and the next assigned target appears. M. Hampson, 7 Hereford Dr., Clitheroe, Lanes BB7 UP. U.K. Reprinted from The Ultimate Magazine with permission. Neil Dewhurst, 2 Chesterbrook, Ribchester Nr Preston, PR3 3XT, U.K. Reprinted from The Ultimate Magazine with permission. 20 You control your laser movement with the 5 key for left and the 8 key for right. Press to fire. Enter the program, put the computer in SLOW mode, and hit RUN and ENTER. FOR PLOT PLOT _ PLOT URi_ PLOT UAL NEXT LET P=URL LET S=URL = URL "a" TO URL Z..URL "0" 2.. URL "fiS" 25-., Z 0- , Z "1" _ "0" PRINT RT URL ■'■7" .P-P; "SCORE TRB P-P.. "RIM FOR . . . " FOR N = 157 TO 165 LET Q = INT **© " • < INKEY THEN GOTO IS 10 11 12 13 14. 15 20 3© 4-0 100' 101 102 103 104- 105 110 120 $="5' 130 14-0 14.5 IF P=Q + 1 OR P=Q+2 THEN LET 150 FOR Z=2 TO 24. 151 PLOT P .Z 152 NEXT Z 153 FOR Z=2 TO 24. 154 UNPLOT P.Z 155 NEXT Z 156 PRINT RT "7 . S . S 160 NEXT N Blaster M. Hampson In Blaster the screen displays a field showing a wall of 7 courses of equals signs. Your blaster, which is on con- tinuous fire, is indicated by an asterisk. You have 200 shots to clear away the wall. The movement of your blaster is automatically to the right; to move it to the left you must press the 1 key. The score, showing the total number of hits, is displayed at the end. Type in the program without using your RAM pack. Put the computer in SLOW mode, hit RUN and ENTER. Graphics notes: Line 4: Inverse equals sign (16). Line 6: Inverse space (16); S (16). 1 LET H=0 2 LET B=S01 3 FOR Z=0 TO 6 4. PRINT RT Z,0; 5 NEXT Z 6 PRINT 7 a 5397 10 20 30 15) + 4-0 60 70 Q0 31 90 100 110 120 130 ,OTO 14-0 203 205 5 10 21S LET P=3 LET p=p -*+ iINKEV$="") *2- POKE 120+U+P, 151 T§ R «^I,= 2 2 S* U + P TO u STEP -17 ^£ E 5 K ^f 1 * 3 THEN GOTO 1JL0 - (P = POKE POKE NEXT GOTO POKE , 15l' , 12a .,128 LET N«N + 1 IF INT (N/112.i -; > N -112 THEN 10 GOTO 3 PRINT "VOUR SCORE * , N PAUSE 50000 CLS RUN Catch 25, or Playing Left Field M. Hampson Your catching glove (or cup or what- ever you want to catch with) appears as a U. The ball comes down and you must move to catch it in your glove. You move into catching position by using all the arrow keys so this requires simultaneous four finger coordination. When you catch the ball, a shift in graphics to the asterisk indicates a successful catch. Your score, which is the total of successful catches, is displayed in the top center of your screen throughout the game. Type in the program. Put your com- puter in SLOW mode, hit RUN and ENTER. Graphics notes: Line 120: a period. Line 150: the letter U. Line 200: an asterisk. 20 LET Q=URL "10" 30 LET R^O 40 LET S=0-0 100 FOR Z = Q/Q TO URL "25" 105 LET P=INT (RND*URL "10") 110 FOR L = Z/Z TO URL "17" 120 PRINT RT L..L+P,;" " ; RT L+Z/Z L+P+Z/Z; " . " 130 PRINT RT Q.R." " 140 LET 0=0t(INKEY$="6") - ( INKCY 141 LET R=R+ (INKEy*="8"> - ( INKEY 150 PRINT RT Q,R."U" 160 IF L+Z/Z=© RND L+P+Z^Z=R TH EN GOTO URL "200" 170 NEXT L 180 NEXT Z 190 STOP 200 PRINT RT Q,R."*" 210 LET 5=5+Z^Z 220 PRINT RT Z/Z..URL "11" ;S 230 GOTO URL "180" SYNC Magazine EZRA GROUP II EZRA GROUP II The ZX81 /80/TS-1000'S are making a name with LOW prices... WE CHALLENGE THE SOFTWARE COMPANIES TO LOWER THEIR PRICES! ForTS-1000/ZX81/ZX80/8K ROM 1 K and 1 6K RAM versions Biorhythms 10 ° Graphics Billboard 1 00 Horse Race 1-00 SPINNER T.M. (like Rubik's) 16K 2.00 Skew-a-Sketch (like Etch) 100 Improved Pause (ZX81) 100 Linear Regression 2.00 CHEWTER T.M. (Like Pac M-N) SLOW 2.95 Shootist 2.00 Random MUSIC! SLOW 2.00 Self Addressed Stamped Envelope Gets YOU our Goodies Catalog ALL ORDERS AND CATALOG REQUESTS GET FREE Galactic Messages PROGRAM. EZRA GROUP II EZRA GROUP II P.O. Box 5222 San Diego, California 921 05 (714) 584-8291 Bombs Away! Ate/7 Dewhurst Your high speed bomber appears at the top of the display as the inverse and moves from left to right. Your targets appear at the bottom of the display as inverse O's. Press any key to drop a bomb at any time. Each time the plane makes a pass over the target area, it drops down closer to the targets. The aim of the game is to hit all the O's before the plane gets too low to make another pass. Enter the program, put your computer in SLOW mode, press RUN and ENTER. Graphics notes: 6: inverse space (16). 10: inverse O (16); S (16). 120, 310: inverse 140, 280, 400: inverse spaces. 145: Q. SEA WAR FOR ZX81 This game is designed for one or two players. Each player has three submarines. As a certain number of points are reached, bonus submarines will be given. When the game is going on the higher the score you get, the more that hostile features will appear on the screen. The features which appear on the screen are as follows: Submarine, Warship, U-boat and Helicopter. Submarine This feature is under your own control and is loaded at the left hand side of the screen. The keys '9' and '0' are the firing buttons for the upward missiles and forward missiles respectively The submarine can be moved in four directions; it can move upwards and downwards by pressing keys T and 6' respectively. In order to move forward, you press key '8' and it will draw back to its previous position when you release the button. Also, the submarine can be moved diagonally upwards or downwards by pressing both keys '8' and T or keys & and '6' respective- ly at the same time U-boat This is the hostile submarine: It drifts under the sea level randomly, from right to left Missiles are fired as it approaches your submarine. Destroying a U-boat scores 20 points Warship This is the enemy destroyer which will release bombs diagonally as it drifts on the sea surface from right to left. The destruction of a warship is done by either firing a vertical missile or, when the submarine is just under sea level, by pressing keys T and '0/ which release a horizontal missile. Otherwise the missiles will just pass under the ship bottom. Each destruction of this feature scores 50 points Helicopter As you reach a certain score, helicopters appear on the left hand corner of the screen; they drop vertical bombs as they hover above the submarine. To destroy the helicopters, vertical missiles can be fired by pressing key '9\ Each helicopter destroyed scores 1 00 points. 'New Game— ADDER— Arcade-type game. Shoot the numbers as they pass across the screen, but watch your total. Each game $9.95 plus $2.00 postage/handling Distributor Inquiries Welcome rfionda 8 Software, 51 Elgin Street, Shelton Stoke-on-Trent ST4 2RD 5 FOR Z= URL "l 1 6 PRINT ' HMM 7 NEXT Z 8 CLEAR — 9 LET B=URL 10 P RI NT - i?§ PSS S=n=o -?; TO *"*- -'~ 128 PRINT RT P,0;"B" 125 IF B THEN GOTO 14-0 TO ? 5 I F XNKEY * = OR *=7 THEN GO 131 LET R=P 132 LET S=G 133 LET B=l 14-0 PRINT RT R,S; '*■** 14.1 LET R=R + 1 " 14-2 LET 5=3 + 1 14-3 IF S>1S THEN LET 5=0 145 PRINT RT R,S,**J" 146 IF R=8 THEN GOSUB 400 2S0 PRINT RT P, O ;"■•* 290 NEXT O 2 99 NEXT P 300 FOR G=0 TO 15 310 PRINT RT P,G; '■'* 320 IF 128<>PEEK (PEEK 1639S+25 6*PEEK 16399) THEN STOP 330 NEXT O 340 STOP 400 PRINT RT R,S;"B** 410 LET B=0 420 RETURN Grand Prix Ate/7 Dewhurst You have just entered the IK Grand Prix. The black-topped track scrolls as you drive your white "H" car toward the finish line. You steer by the Z and M keys. You must avoid hitting the parked cars and running off the road. If you do crash, the race ends and your odometer reading appears. Each line scrolled adds one to your reading. The aim of the race is to drive as many miles as possible. Enter the program, put your computer in SLOW mode, press RUN and ENTER Graphics notes: Line 40: Inverse H. Line 50: Inverse space. Line 60: A; inverse space; A; inverse space. 5 LET F=URL *'-12" 10 LET P = URL •10" 20 LET R = URL "7" 30 PRINT RT 10,P."N" 40 LET G^s'S" 45 LET F = F + 1 50 IF RND>.3 THEN LET G* = "B" 55 SCROLL _ 60 PRINT TRB R, "■*".; G «.;"■"; G*; " K";RT 9.P; " '* RNt> F<=0;"» ff RN6 F >0; RT 10, P.; 70 IF R>2 THEN LET R=R-2*RND 80 IF R<10 THEN LET R=R+2*RND 90 LET P=P-(INKEY*="Z") + ( INKEY 100 IF PEEK (PEEK 16398 +256 *PEE K 16399) =126 OR F<0 THEN GOTO 30 110 PRINT TRB 20; F SYNC Magazine SOUNDwithZX-81! SOUND with ZX-81 ! MAKE AMAZING SOUND EFFECTS WITH YOUR ZX-81 Timex Sinclair 1000 Incl. airmai" postage IE £UIM A"0 I * The ZON X-81 SOUND UNIT is completely self-contained and espe- cially designed for use with the ZX-81 . It just plugs in— no dismantl- ing or soldering. * No power pack, batteries, leads or other extras. * Manual Volume Control on panel— ample volume from built-in loud- speaker. * Standard ZX-81— 16K Rampack or printer can be plugged into ZON X-81 Sound Unit without affecting normal ZX-81 operation. * Huge range of possible sounds for games or: Music, Helicopters, Sci-Fi, Space Invaders, Explosions, Gun-shots, Drums, Planes, Lasers, Organs, Bells, Tunes, Chords, etc., or whatever you devise! * 8 full octaves. Uses 3-channel sound chip giving programme control of pitch, volume of tones and noise, all with envelope control. * Easily added to existing games or programmes using a few simple "BASIC" lines or machine code. * No memory addresses used — I.O. mapped. FULL Instructions with many examples of how to obtain effects and the programmes, supplied. Fully Guaranteed. Payment may be made by Bank Cheque or International Money Order in U.S. $ or £ Sterling Payable to: sis J m *> P.O. Box 6 Ware, Herts England Phone #0920-3182 Visa-Mastercard accepted Send account # with name & address 8KR0M IK RAM David B. Ornstein Parser Routines This article is the third in a series discussing the ZX81 Parser. Since the first two articles (SYNC 2:3 and 2:4) may have been a bit too abstract for some readers, I hope this discussion will pull the previous articles together. In the first article I covered the basic concepts common to all parsers, and in the second article I described the imple- mentation of the parser in the 8K Basic ROM: the character fetch routines, the CLASS tables, and the executive routine that was responsible for controlling over- all operations. In this article we will look at some of the routines that are called by the executive to perform actual oper- ations. These operations include, but are not limited to, PLOTting a point on the screen, PRINTing a character on the screen, and executing a GOTO statement. RUNning a Program in Basic Before taking up the details of any particular command, let us review the method used by Basic to RUN a program. In the parser's executive routine a pointer must be passed to the line it is to execute. This pointer is passed to the exec(utive) in the system variable CH-ADD. A loop (at 066Ch in the new ROM) is responsible for keeping track of what line in the program we are currently executing and where it is stored in the computer's memory. The way the computer stores a program in its memory is seen in Figure 1 which represents a single program line. The first two bytes of the line contain the line Figure 1 : A Line Representation. 1 2 3 1 4 Text of Line ENTER number of the represented line. These bytes are stored in MSB/LSB (Most/Least Significant Byte) order. This is the oppo- site of the standard practice with a Z80. The next two bytes hold a standard Z80 LSB/MSB 16-bit representation of the length of the line, including the ENTER (NEWLINE) at the end. When the program has more than one line, the computer is responsible for keeping the records that represent each line of the program in numerical order. With the information supplied with each line, the computer has enough data to effectively "walk" through the program from one line to the next. This is accom- plished by adding to the address of the first byte of the text in the line, and the length of the line, as specified in the two length bytes. The result of this calculation is the address of the next line in the program. Thus, the Run-Executive, as it will be referred to later, must perform only simple operations such as addition 24 to RUN a program. A basic outline of the operations performed by the Run- Executive is as follows: 1) Load a variable (called NXTLIN) with 16509. This is the address of the first line of the program. 2) Set CH-ADD equal to NXTLIN. 3) Call the parser to execute the line. 4) If there are any errors currently logged, then stop, and report them, else, 5) If the BREAK key is depressed, stop with a D report code, else, 6) Add to NXTLIN the length of the current line. 7) Go back to step 2. Figure 2 gives the code for the Run Time Executive, Take a moment now to study it to get a general idea of what is transpiring. The essential facet of this routine is that, when a command handler is called by the parser, it can modify the NXTLIN pointer; this is, in fact, how a GOTO statement works. The destination of the line number (i.e., 100 in GOTO SYNC Magazine Sinclair Hi-Res Graphics + 48K RAM + 8K EPROM Programmer ZX-G Expansion Unit Plttg into Extended Use Introducing Hi-Resolution Graphics for the Sinclair ZX-81 Now you can create detailed graphics images with the new, high quality, low cost ZX-G Expansion Unit. Quality Graphics The ZX-G gives your ZX-81 the ability to create memory- mapped graphics images with a resolution of 256 X 192 pixels. — Graphics images can be drawn, moved, rotated, mixed with text, saved on cassette or printed. — Excellent for Computer Aided Design, education and games. Powerful Software! (cassette included) — Generate lines, circles, and rectangles with ease! — A dynamic graphics cursor facilitates rapid design. — Graphics animation is fully supported! Memory Expansion! — With the ZX-G. you can expand the memory of your computer to 48K! — Up to four hi-res. graphics screens can be stored in addition to a 16K program! EPROM Programmer Support! — With our optional EPROM programmer, (fully transparent), 2716 (8K) EPROMs can be programmed, verified and run directly in memory map (2000-3FFFH) Compact Design! — The total unit (including power supply) is enclosed in an attractive vinyl-clad aluminum case. — Cable and power cord included! — 90 Day Warranty (parts & labor) ZX-G Expansion Unit $99.95 RAM/EPROW! Option $79.95 (includes 32K RAM + four 2716 EPROMs, ZX-G required) Free Graphics Software Mail Order to: Southern Computer Systems 630 Main Street Shelbyville, Kentucky 40065 or call collect: (502) 633-5640 NEXT- LINE: a. a^oiiug vi iiic nun i im« LD executive. HL, (ERR-NR) LD (NXTLIN) p HL BIT 7, (HL) EX DE,HL JR Z, STOP-LINE CALL TEMP-PTR ; $004D LD (HL) ,*0C CALL LINE-RUN ;*0CC1 REG 1, (FLAGS) STOP- -LINE: LD A, 1 1000000b BIT 7, (PR-CO LD (X-PTR) , a CALL Z f COPY-BUFF CALL X-TEMP ;*14A3 LD BC,*0121 RES 5, (FLAGX) CALL LOC-ADDR ;*0918 BIT 7, (ERR-NR) LD A, (ERR-NR) JR Z, STOP-LINE INC A LD HL, (NXTLIN) JR Z, REPORT AND 5°.X i 63 ' HONTCORL . UU 2S13S--PH ONE 304--3S4.-2237 3 REM REMISED 3-4-32 GOTO SIS T ° RUN PROGR * M TYPE GOTO*!©*™ M * NIPUL " TE LIST TYPE 10 LET B = INT (RNO#TOT,» +1 12 CLS 13 PRINT " HIT Q FOR ME 14- RETURN IS LET D$=INKEY$ i? &T8&" '" ™ EN GOTO " e 20 PRINT "IN THIS MODE, ";C»; 21 RETURN 25 PRINT "YOU SRID IT URS 26 RETURN 30 PRINT TAB 8, ;o$ 'YOU RRE CORREC 31 RETURN 100 PRINT T$ 104- PRINT RT N YOUR NRHE. 110 INPUT C* 115 CLS 120 PRINT "HELLO, ";C$;"." 125 PRINT "I UILL HELP YOU LEftR N SOME *;M*;**S RND THEIR ";N$;**S . THE MENU OF THINGS I CRN DO I 126 PRINT 130 PRINT T" 131 PRINT 132 PRINT 133 PRINT 134- PRINT 135 PRINT "PLEASE TYPE IN THE N UMBER OF YOUR CHOICE, ";C$;", 14-0 INPUT R 14-2 IF R<>1 RND R<>2 RND fi < > 3 R ND R<»4- THEN GOTO 14.0 145 CLS 150 GOTO R4200 200 PRINT "REUIEUING THE LIST-- 205 GOSUB 20 210 PRINT "I UILL DISPLRY R " ; N 5.. 0, "PLEASE TYPE I "1. REUIEUING THE LIS *2- PRACTICE DRILL" *3. SPEED QUIZ" '4-. EXIT THE PROGRAM" $.; " ON THE SCREEN , PAUSE, THEN D ISPLRY THE ";M$.;". AFTER REUIEU ING ALL ";TOT;" I UILL SUXTCH TO SHOWING THE ",*%," FIRST. TYPE A NUMBER FROH TO 3--0 BEING A UERY FAST REUIEU AND 9 THE SLOW EST. " 215 INPUT Z 217 IF Z<© OR Z>9 THEN GOTO 215 220 FOR A=l TO TOT 225 GOSUB 12 2 30 PRINT RT 10,3; B*(R);" ", 235 PAUSE 20+Z*10 236 POKE P,0 24.0 GOSUB 15 24-5 PRINT A* (A) 250 PAUSE 20+Z*10 251 POKE P,G 255 GOSUB IS 260 NEXT A 265 FOR R=l TO TOT 270 GOSUB 12 275 PRINT AT 10,8;R*cm:" "; 280 PAUSE 20+Z*10 231 POKE P,Q 285 GOSUB 15 290 PRINT B* lAJ 295 PAUSE 20+Z*JO 296 POKE P ,Q 300 GOSUB 15 305 next A 310 GOTO 2-^tf 4-00 PRINT "PRACTICE DRILL " 4-05 GOSUB 20 4-10 PRINT "I UILL GIUE YOU IS " . M$.; "S IN SUCCESION. YOU TYPE I N THEIR ",N*;"S. THEN I UILL GI JE 15 ";N*;"5 RND YOU TYPE IN TH E ";M$;"S. PRESS ENTER TO START "4-12 4.15 4-19 4-20 4-25 430 435 4-4-0 445 447 N$; " 450 460 462 4-65 4-70 4 72 473 475 477 CB) ; ' 4-78 479 480 490 LET U=0 INPUT Z* IF F2 THEN GOTO 435 FOR A=l TO TOT LET E* lA.» =CHR* NEXT A FOR R=l TO IS GOSUB 10 IF E$ iB> ='*X" THEN GOTO 440 PRINT RT 9,0; "TYPE IN THE " FOR--" PRINT RT 10,8;A»(B) INPUT D* GOSUB 25 GOSUB 16 IF LEN D$=L2 THEN GOTO 4^5 LET D*=D*+" GOTO 4-70 IF D$=B$(B) THEN GOTO 490 PRINT TRB 8; "NO, IT IS ";B> PAUSE 200 POKE P,0 GOTO 497 IF NOT F2 THEN LET E*(B)="X "0S PRINT RT 9,0, "TYPE IN THE '* FOR — " PRINT AT 10,B.;B$IBJI INPUT D* GOSUB 25 GOSUB IS IF LEN D$=L1 THEN GOTO 545 LET D*=D*+" GOTO 530 IF D*=A*»B> THEN GOTO 550 PRINT TRB 8; "NO., IT IS *';A* PAUSE 24-0 POKE P.O GOTO 575 GOSUB 30 IF NOT F2 THEN LET E*tB>="X 492 493 4-95 4-96 4-97 500 505 510 512 , M$J • 515 520 525 527 530 535 54-0 545 550 iB».; ' 553 554- 555 550 565 570 PAUSE 120 571 POKE P,Q 572 LET U=U + 1 5 75 NEXT A 5S0 CLS 585 PRINT "YOU GOT •;c»; •A UERY GOOD SCORE IN •HIT ENTER TO RETURN 586 PRINT DEED. " 590 PRINT TO MENU." 592 INPUT D» 595 GOTO 990 500 PRINT "SPEED QUIZ " 60S GOSUB 20 610 PRINT "I UILL GIUE YOU ";M$ ; "S-TYPE IN THE M ;N|; "S. AFTER 6 SEC. I UILL DISPLAY YOUR SCORE I UILL GIUE YOU 1 POINT FOR A CORRECT ANSUER TAKE 1 POINT FOR AN INCORRECT ANSUER AND NOT DO ANYTHING IF YOU ONLY PRESS ENTER PRESS ENTER TO START." 612 LET U=0 615 INPUT D$ 620 POKE P-1,0 525 POKE P,0 630 GOSUB 10 64-0 PRINT AT 10,8, A* IB) 64-5 INPUT D* — _- 64-7 IF PEEK tP-lJ +25b*PEEK IP) < 6 1936 THEN GOTO 580 _^ 550 IF D$ = "" THEN GOTO 630 655 GOSUB 16 m _ _ m fiS7 IF LEN D$=L2 THEN GOTO t?O0 S3 LET D$=D$+" 659 GOTO 657 660 IF D$<)BflB) THEN LET U =U - 1 565 IF D*=B*IBJ THEN LET U=U + 1 570 GOTO 63C- _, , 300 PRINT YOUVE COHE UERY WELl •;Cf; " . " ?OS PAUSE 606 POKE P . 307 PRINT 810 PRINT I HOPE YOU HP.'JE i- _ED YOURSELFAND LEARNED SOMCTHJN ~3 12 PRINT 3 15 PAUSE 120 3 16 POKE P.. O _ 320 PRINT "******* HAUE A NICE DAY *****»**" 322 PAUSE 1O00 823 POKE P . O 324 CLS 325 GOTO 100 990 CLS 995 GOTO 13^ 996 SAME L* 997 GOTO 100 «——-»—-«-.. 1000 PRINT "LIST LGHDER PROGRAH 1005 GOTO 1327 1008 LET F1=0 1009 PRINT "TYPE THE TITLE OF V C UR LIST." 1010 INPUT T$ 10 11 LET P = 164-3/ 1012 LET F2=^ 1013 LET 0=235 10 15 CLS 1020 PRINT "TYPE THE TITLE (5INGU LflR) OF THE 1ST CLASS OF TTEHS I N YOUR LIST. THE 1ST CLASS SHOU LD CONSIST OF THE LONGEST ITEMS IN LENGTH IF POSSIBLE-" 10 30 INPUT H* 1035 CLS 104-0 PRINT ARE IN THE 1ST CLASS"?" 1050 INPUT LI 1055 CLS 1060 PRINT "TYPE THE TITLE (SINGU LAR) OF THE 2ND CLASS." 107O INPUT N* 1075 PRINT "HOW MANY CHARACTERS ARE IN THE LONGEST ITEM IN THE 2ND CLASS?" 1080 INPUT L2 1085 CLS 1090 PRINT "HOU HANY ITEMS IN EA CH CLASS OF THE LIST?" 1095 INPUT TOT 1100 CLS _ TTTLE-";T* TITLE 1ST CLflSS-";M$ LONGEST STRING 1ST C 114-0 PRINT "IS THIS INFORMATION CORRECT-Y/N?" 114.5 INPUT Z* 1150 IF Z$="N" THEN RUN 1000 1151 IF TOT<4-0 THEN LET F2 = I 1150 DIM A* (TOT, LI) 1165 DIM B*CTOT,L2) 1170 DIM E$ (TOT) 1175 CLS 1185 PRINT AT 10,0 T ITEM IN THE 1ST 5T ITEM IN 2ND CLASSTHEN 2ND ITE M IN 1ST CLASS , ETC . " 1190 FOR A=l TO TOT 1200 IF NOT Fl THEN GOTO 1250 1205 SCROLL 1210 PRINT M*; ";»*c**j 1215 SCROLL 1220 PRINT N»; "--"; Q*iA) 1225 INPUT Z* 1230 IF 2J= THEN GOTO 1290 1250 SCROLL 1255 PRINT M$; " "; 1260 INPUT A$lA) 1265 PRINT A$(fl) 1270 SCROLL 1275 PRINT N*; "--"; 1280 INPUT B*(A) 1285 PRINT B*(A) 1290 NEXT A 1292 CLS 1295 IF Fl THEN GOTO 1320 1300 PRINT AT 10,0;" UE UILL NOW REUIEU EACH PAIR OF ITEMS. WHEN THEY COME ON THE BOTTOM OF TH E SCREEN, HIT ENTER IF THEY ARE ~ X AND THEN ENTER " THEN ENTER THE IS CLASS/THEN 1 ENTER EACH P BEFORE. " 'HOU MANY CHARACTERS LONGEST ITEH IN THE ORRECT. HIT F THEY WRONG F THEM AS YOU DID 1305 LET Fl=l 1310 GOTO 1190 1320 PRINT "TYPE IN THENAME YOU UISH TO DER . " INPUT 3AUE THIS PROGRAM UN 1105 PRINT 1110 PRINT 1115 PRINT l_ASS-"; Ll 1120 PRINT 1125 PRINT LASS-"; L2 1130 PRINT 1135 PRINT 1325 1326 PRINT '.v27 PRINT 1328 PRINT 1330 PRINT 1335 PRINT 1336 PRINT 1337 PRINT 1338 PRINT 1339 PRINT 1340 PRINT F YOUR MO TO SAVE JT! AS YOU I 345 INPUT SAUE NAME-- ; J-* "i, "2. LOAD NEW LIST " REUIEU ,'REUISE LIS '3. CHANGE SAUE NAME" 4. SAUE PROGRAM" 'TYPE IN THE NUMBER O CHOICE. IF YOU INTE START RECORDER AS "oO PRESS ENTER." TITLE 2ND CLASS-"; N* 'LONGEST STRING 2ND C "ITEMS IN LIST-"; TOT 1346 CL 1347 IF 1348 13 49 ,350 A IF A = IF A = IF A = 1355 GOTO ^ THEN GOTO 99S 1 THEN RUN 1007 3 THEN GOTO 1320 2 THEN GOTO 1300 1330 ZX81 (H computer ware TS1000 CASSETTE 1 (16K) $9.95 CASSETTE 2 (16K) $9.95 SNAKEBITE BA TTLE Eat the snake before it eats you. Variable speed. Create your own hazards. Demanding game of military strategy that can be played by 1 to 4 players. STARTREK FUNGALOWS Use graphic photon torpedo attacks to kill off the highly mobile Klingons. Save civilization by bombing the ever-multiplying fungus. Beware - it tights back. CASSETTE 3 (16K) $9.95 CASSETTE 4 (16K) $9.95 STARSHIP TROJAN PRINCESS Oh KRAAL Pit your wits against the dangers of outer-space and try to save your damaged space-craft. Face the monsters hiding in the underground complex to find the treasure and save the Princess. CRAZY-CARDS CUBE Learning the rules does not seem to help. Totally addictive for cheats. Use your computer to solve the mysteries of the Rubik Cube. IK and 2K Program Packs also available - Write for details Check or Money Order payable to: CLEVA Computer Ware, 92 Wyckoff Street, Brooklyn, New York 11201 New York Residents only add Sates Tax. Add $1.50 for Shipping and Handling September/October 1982 33 Teaching with the ZX81 Eric Deeson The Educational ZX80/1 Users 1 Group (EZUG) had a triple celebration in Jan- uary. First, we were able to breathe a sigh of relief that we had survived a year of frenzied activity. Secondly, we welcomed the thousandth subscriber to our bimonthly newsletter. Thirdly, we launch- ed our first educational ZX81 programs, fourteen of them in fact. Now, some months later our "membership" has pas- sed 1500, and we have over forty validated and popular ZX81 programs on our list. I make these points not because I want to plug the group, but to show that in Britain the year-old Sinclair micro is being taken seriously as a teaching resource. This will remain true, for a couple of years at least, despite the appearance of the remarkable Spectrum. While Spectrum and ZX81 programs are not interchangeable, they bear such a close relationship that rapid conversion is straightforward. Our group's directory of suppliers to the ZX market currently lists organ- izations producing educational software for the machine. Also MUSE, Britain's leading educational computing organi- zation, has given this record-breaking new machine a lot of support. Some support has come from Sinclair Research as well; in particular their educational software awards scheme attracted a great deal of interest. Although actual data are very hard to come by, there is no doubt that already the ZX81 is by far the most popular micro in British schools. It compares very favor- ably with the longer-established front runners such as the Apple, the PET, and the Research Machines 380Z/480Z (a stolid, fairly old British microseries), and it is way ahead of the popular but newer BBC machine. The number of ZX81s in use in British Eric Deeson, Highgate School, Balsall Heath Road, Birmingham B12 9DS, U.K. Eric Deeson is the organizer of EZUG. For information about EZUG, send two international postal coupons (for air mail) to him at the above address. 34 schools by now may exceed 10,000. This is as many as all other micros combined. Such success must be seen against the background of almost universal antagonism by the decision makers in our educational system. "The ZX81 is only a toy" is a common statement from inspectors and advisers; "Forget it," they say. A senior inspector with a large education authority even publicly stated the following: "If I come across a ZX81 in any of my schools, I'll stamp on it." British teachers tend to have a fairly low opinion of their advisers; such attitudes hardly help though I believe they are symptomatic of fear more than of any- thing else. In a few areas, the authorities are now considering adopting the ZX81 as the official machine for the primary schools (Grades 1-6). But I know of none which provide much of the support that the teachers need such as courses, advice, software development, and so on. Yet the ZX81 continues to infiltrate the schools at a breakneck pace, and the teachers are joining the Educational ZX80/1 Users' Group at a similar pace. The reasons for this are both external and internal. Schools and teachers are under pressure from pupils and parents to provide effective computing facilities and courses. That pressure is mainly linked to the ZX81 since it is by far the most popular micro in British homes. Areas of Use How are micros coming to be used in British education? The answer is not just applicable to the Sinclair range, of course, since to some extent at least the ZX81 can attempt anything other micros can do. And the answer is not just applicable to Britain because educational computing in North America is as progressive, suc- cessful, and exciting as on this side of the Ditch. Furthermore, the answer is not just applicable to schools and colleges. The ZX81 is a help with the children's aca- demic work at home, and many university departments have ZX81s around. Classroom Uses We can break the classroom uses down into the following categories. Computer awareness. The primay aim is to increase familiarity with the com- puter and its uses. Most schools in Britain now attempt at least a few hours of this with all pupils. Computer studies. The ZX81 is the apparatus used for formal computer instruction. Computer-assisted learning. The com- puter joins the army of resources available for teaching in most subjects. Other Uses in the School Other school uses not directly in the classroom include: Administration. The computer helps the daily routines of the school as it does in any other business. Interfacing. Again the computer helps as in many other fields with data capture and process control. Computer clubs. Many schools have thriving clubs in out-of-class time. Fund raising. A major educational activity in Britain nowadays is the use of computer games for fund raising! Developing software and hardware. Not a few schools find their facilities used by pupils (and teachers) for developing soft- ware and hardware products for sale. SYNC Magazine BYTE -BACK modules 64-K MEMORY $119.?? BY TE-BACK Co M-64 INSTANT INFORMATION r yL WITH c^Cr BYTE-BACK'S MD-1 MODEM only $1 19/ Kr WIRED and TESTED $149.95 Use your phone to connect your "LITTLE"ZX81 to the "LARGEST" computer networks in the world. With BYTE- BACK s MD-1 MODEM connected all you do is dial a phone number (usually local), press a few keys and watch the data appear on your TV screen. (Software is included) This MODEM can be used in either the "originate" or "answer" mode with selectable baud rate. You can have immediate access to: UNIVERSITY COMPUTERS, DOW JONES, UPLAND MORE ! As an extra bonus an RS-232 port is provided to allow you to drive all standard RS-232 peripherals. (75 to 9600 Baud) BYTE-BACK'S BB-1 CONTROL MODULE $59.oo In Stock! WIRED and TESTED $69 • 8 Independent Relays (with LED status indicators) • 8 Independent TTL Inputs (with Schmitt trigger buffers) • By using a single POKE command you can change and latch the status of each of the 8 relays • Your ZX80/1 can read the status of all 8 inputs by the use of a single PEEK command. • A comprehensive manual is in- cluded that has complete application details. WIRED and TESTED $129.95 IN STOCK! SAME DAY SHIPMENT! BYTE-BACK'S M-64 extends the memory of your ZX81 or Timex-Sinclair 1000 to a full 64-K. It's user transparent. It plugs directly into the back of the ZX81 and has an expansion port to allow you to still use a printer. No extra power supply is required. It has all standard features plus the area from 8-16-K can be switched out in 2-K incre- ments for memory mapped peripherals, PROMS, etc. Same proven reliability as our M-16 with thousands in use. EXPAND YOUR 16K SYSTEM (M-16) $59.95 iVTE-iACK Co WIRED and TESTED $69 95 i^fltfH^^SB If you have a Sinclair 16K RAM module and need more memory, expand it to 32K and beyond by using BYTE-BACK M-16 MEMORY MODULES. You can't connect two Sin- clair 16K RAM modules together, but you can connect one Sinclair 16K and one or more BYTE-BACK 16K modules to get all the memory you need. THOUSANDS IN USE WITH PROVEN RELIABILITY IN STOCK - SAME DAY SHIPMENT RS-232 Module $59. 95 IN STOCK/WIRED and TESTED $69.95 Allows you to connect ZX81 to all RS-232 printers & terminals. ALL MODULES CARRY 90-DAY WARRANTY TRY BYTE- BACK MODULES FOR 10 DAYS WITH NO OBLIGATION Remember with: BYTE- BACK modules you are NOT limited to using only one module at a time! Q CL X CO H X > O CD CO CO O CM Csl GO . m 9 cm -i 2 _I ° _ CO > w « £ W CL D M-64 Kit $119.95 D M-64 Wired and Tested $129.95 D M-64 Blank PC Board ... $19.95 D BB-1 Kit and Manual $59 □ BB-1 Wired and Tested and Manual $69 a BB-1 Blank PC Board and Manual $29 Shipping and Handling $4.95 D M-16 Kit □ M-16 Wired and Tested . . D M-16 Blank PC Board D Modem Kit . □ Modem Wired and Tested □ RS-232 Module Kit D RS-232 Module Wired and Tested . $59 95 ■ $6995 . $19.95 . $99 95 $11 9.95 . $5995 . .$69.95 ORDER PHONE (803) 532-5812 Exp Date _^ Card No Name Bill My D Visa D MasterCard Address City/State/Zip Mail To BYTE-BACK CO. • Rt. 3. Box 147 • Brodie Rd. • Leesville, S.C. 29070 Figure 1. Flow Chart for Simple Q/A Routine. PoseQ y INPUT Answer Pose INPUT Answer Score = Score + 1 "Wrong'' Figure 2. Flow Chart Adding Scoring Feature. Computer-Assisted Learning Probably the main educational interest of most teachers and parents with a ZX81 is computer assisted learning (CAL). McGraw-Hill's new Devils DP Die dorian' (which I hope you all get a chance to read!) has this to say: CAI n. (Computer-Aided Instruction.) The misguided attempt to replace each teacher in the Bronx with 60 on-line terminals. CAL n. (Acronym for CALifornia or, archaic, Computer-Aided Learning.) A superior West Coast (USA) version of CAI in which each teacher is replaced by 25 on-line terminals. Some people think that in the not too distant future teachers will be replaced by computers. I do not agree, even though micros are far more effective than term- inals. Indeed I shudder at the picture of a school in which the children spend all their time connected to a computer, living like chickens in a battery farm. (Impossible future? No! A recent book describes how a computer could check continuously that the user's eyes are following the screen display!) At the moment, however, we have hardly taken a couple of steps along the road to such computer systems. The 36 ( Next A Yes —4- Subsidiary questions or just "Try again" No Help specific toB Help specific toC Help specific toD No(H) Thorough general HELP Detailed score- specific reinforcement Figure 3. Flow Chart for Diagnostic Program. T ZX81, like other established micros, can run only fairly simple teaching programs. It will be a long time before the PLATO approach reaches school level! Such programs are, on the whole, simple mechanizations of the teaching machine material of a couple of decades ago. In most cases they are very crude, with each frame (unit of teaching) being on the lines of those shown in a flowchart such as shown in Figure 1. To program this kind of thing is obviously fairly straightforward (at least, as long as the question requires a very simple NextQ "objective" answer). It can be elaborated by adding a scoring feature as shown in Figure 2. Teaching is not like that though. Pro- grams must therefore progress towards mirroring classroom technique in sophis- tication, flexibility, and explanation. Thus correct responses require that the user be further checked for understanding; each incorrect response should lead to relevant remedial assistance. The flow chart in Figure 1 rapidly becomes unmanageable and must be replaced with the type in Figure 3. SYNC Magazine For the first time - AVAILABLE IN THE USA! 4 NEW Handbooks for your Sinclair ZX-81 or Timex-Sinclair 1000!! ******** ************* ********* ****************! MASTERING MACHINE CODE ON YOUR ZX-81 by Toni Baker Until this comprehensive, yet easy-to-understand, handbook, there was virtually no material available about the ZX machine code. Using this guide you'll learn the ins and outs ofZX machine code translation. Discover the secrets of the ZX-81 , and even see how to adapt the code to the ZX-80 machine. When you understand the language translations between BASIC and the ZX machine code, you'll enjov the workings of your computer to the utmost! 49 EXPLODING GAMES FOR THE ZX-81 Edited bv Time Hartnell Galactic Intruders, Breakout, Checkers, Death Maze, Smugglers Mold, and fortv-three other favorites are all here, newly adapted especially for you and your new ZX-8 1 personal computer. This fascinating gamebook gives you programming instructions for all 49 marvelous games PLUS complete and easy-to-understand game rules. This wonderfully exciting hardcover playbook can be yours, order below. MAKING THE MOST OF YOUR ZX-81 by Tim Hartnell All new for you and your new ZX-8 1 , this handbook focuses on the additional features of the ZX-81. You'll have new games and use- ful learning tricks, and you'll also see how to write programs that really work. It will guide you through start to finish, using each feature and function of your new ZX-81 personal home computer. THE ZX-81 POCKETBOOK by Trevor Toms This handy new programming manual really gets you into ZX-81 functions. Don't just type someone else's programs . . .now you can create your ou n and understand why they work. It's fun to learn all about computing with the ZX-81 POCKET BOOK as a guide. You'll see what your new ZX-8 1 can do, and what extras will make it able to do even more . . . see how to use ZX-81 BASIC in the best ways learn to avoid frustration and retyping with program and data file storage and retrieval techniques — and for ZX-80 owners, you'll learn how to convert your ZX-80 to the advanced ZX-81 ( apabilities. And there's so much more! This road map to the ZX- Hl can be yours it's worth every penny' I T sing these books you'll be amazed at how fast vou'll become a ZX-81 wizard. Ofcourse, if you don't find the books helpful and inter- esting return them within 15 days for a full refund, and owe nothing. RESTON PUBLISHING COMPANY c/o Mail to: PRENTICE-HALL INC., Book Distribution Center Route 59 at Brook Hill Drive, West Nyack, New York 10995 Please send me my 15-day trial copies of the following titles: MASTERINGMACHINECODEONYOURZX-81 f byToniBaker,(R4262-3),$18 95 49 EXPLOSIVE GAMES FOR THE ZX-81, by Tim Hartnell, (R2087-6). $16.95 MAKING THE MOST OF YOUR ZX-81, by Tim Hartnell, (R4189-8), $16.95 THE ZX-81 POCKET BOOK, by Trevor Toms, (R9525-8), $16.95 Name. , Address- , City State- Zip- vrsA- Now you can charge your orders! Just fill in the information below: VISA □ □ MASTERCHARGE account #. signature- expiration date- Save! If check or money order, plus your state's sales tax. accompanies your order, publisher pays all postage and handling charges Same money back guarantee applies Dept V V-0881-Z8-(7) 8K ROM ; IK RAM 4K ROM ; IK RAM Maps and the ZX80/81 Harry Doakes Think about maps for a minute. We see them in one form or another almost every day, but we usually do not think about them even though there are some highly sophisticated theories about maps. We simply use them. We just want to figure how to get from here to there. On a computer, however, a map is something we have to think about. Many computer games— and other applications, too— use maps to store and represent information. In this article, we will examine some ways of putting maps into your ZX80 or ZX81. We will also see how the Sinclair computers can generate complex maps by themselves. Starting at the Beginning What exactly is a map? Let us define it at this point as a representation of a group of places and of the ways of getting from one place to another. One of the most familiar types is the road map. Cities and towns marked on the map with different types of dots; the roads are shown as lines of various sizes and colors. The towns are the places on the map, and the roads connect each of them to other towns. One of the defining characteristics of a map is that every place on the map must be connected, somehow, with every other place on the map. Maybe the connection will not be direct. On a road map, for example, the route from town A to town B might lead through several other towns along the way. But, if you literally "can't get there from here,' 1 the two places are not really on the same map. Actually, most road maps contain plenty of other information besides locations of towns and roads. For example, since a road map is usually a picture of an entire region, it also shows such features as rivers and lakes. In addition to those extra details, all the distances on a road map are usually to scale. "To scale" means that distances on the road map are proportional to the Harry Doakes, PO Box 10860, Chicago, IL 60610. 42 distances in the real world. Thus one inch on the map might represent ten miles in the real world. That may seem pretty obvious, but not all maps are drawn to scale. Many do not need to be. Concentration A map drawn to scale contains a lot of information concentrated in a relatively small space. We scan the map quickly and get the information we need fast. That is, we process the information the map contains visually. The very complete to-scale map is not nearly so useful to a computer though. To understand why, think about what you do to figure out how far it is from New York to Los Angeles. 1) You open up the map. 2) You find New York. 3) You find Los Angeles. 4) You measure the distance between the two cities. Now think about what a computer has to go through to do the same thing: 1) It has to scan the entire map, one small section at a time, to look for New York. 2) It must repeat the whole process to find Los Angeles. 3) Having figured out where the two cities are, it has to measure the distance between them. Generally that is the easiest part of the task. But before any of that happens, the computer must be able to scan the map. Since this generally means the map must be stored in the memory of the computer, lots of memory is required, much more than is reasonable for something as simple as figuring out how far it is between two cities. The simple truth is this: human beings are good at processing visual information. Computers are not. As a result, the best kind of map for a human being may be the worst sort of map for a computer. A Computer Map The simplest kind of computer map is the equivalent of a map actually drawn on a piece of paper. For example, enter and run the program in Listing 1. Your screen display should look something like Figure 1. Figure 1. N DISTANCE =4- L=5© Listing 1. . 8KROM 10 LET L = INT (RND#100) 2© LET N = INT (RND*100) U ^i& t -"™ , :?.??T? ae - 50 FOR R = TO 9 60 PRINT " . ": 70 FOR B=0 TO 9 80 LET R*=" " .,!£ IZ 3-2*5 4 " B=N T MEN LET fl*-"N" m RRiN?*gj? =L then let r *-"*- 1 ' 120 NEXT B 130 PRINT " . " 14-0 NEXT R 150 PRINT " .•■ Changes for 4K ROM 10 LET L=RND(100)-1 20 LET N=RND(100>-1 This is a randomly generated map of New York and Los Angeles. The "N" represents New York, and the M L" Los Angeles. It certainly looks like a map— a sort of map, anyway. And it is relatively easy for a human brain to understand. But it is not nearly so easy for a computer to work with. Remember that, using just the map, a computer calculating the distance between the two cities would have to scan every space on the map to find each of the cities. That is not too large a problem on a tiny map of 100 spaces. But for a map representing the entire United States, featuring a significant number of cities, it would take lots of time— and lots of memory. A human brain has a huge capacity for processing and storing information, but a computer (especially a small, personal- size computer like the Sinclair) does not have the luxury of all that spare memory. For most computerized maps, drawing out the map for the computer to work with will not be very helpful. A More Coordinated Version The computer has several ways of handling this information instead of act- ually drawing out a map. One is to assign coordinates to each important place on the map. In Listing 1, for example, lines 10 and 20 assign a random position to SYNC Magazine a«&asaa tois Floppy Disc Hi-Res Vid. Printer Plotter Memory Speech Modem A-D D-A Etc. Etc. From over 50 manuf. AERCO llllllllllllll V**^^ ZX STD BUS INTERFACE • ONBOARD MEMORY EXPANSION OPTION • MEMORY-MAPPED PORTS • PROVIDES POWER TO ZX • ALLOWS OVER 6M CABLE • HI-POWER BUS BUFFERS • DELIVERY FROM STOCK ^ w ^^ o o o o OPTIONS: • CONVERT ZX EDGE CON. TO RIBBON HEADER $30 • 2K RAM EXPANSION $15 • 4K RAM EXPANSION $25 BOX 18093 AUSTIN TX 78760-8093 (512) 385-7405 3UG!)0Q.&Dia *<*'* 1 ABERSQFT 7 MAESAFALLEN, BOW ST, DYFED, SY24 5BA ZX81 & Spectrum Games Now NEW LOW prices nn PROGRAM PRICE Chess 1.4 $17.95 10 levels m c Adventure $17.95 1 40 locations based on the original Invaders $8,95 Fast m c arcade action Mazeman $8.95 All the features of the original arcade version m c Add $2.00 for postage/handling OMNI TEMPLATE FORZXSOand ZX-81 WHA T IS OMNI TEMPLA TE? It is a template program for generating other programs. While developing programs, our staff needed a collec- tion of general utilities to avoid the burden of repeating the same routines over and over. This gave birth to OMNI TEMPLATE. We found it so effective that we decided to share it with others. WHY SHOULD YOU HA VE IT? It is a great training tool. It helps you to develop a habit of writing professional-looking programs rather than rag-tag patch works. It makes programming fun. WHA T DO YOU GET? You will receive a cassette tape of OMNI TEMPLATE Program prerecorded and ready to use. Three addition- al programs: RACING, INDEX-CARDS and FIT- POINTS, which were developed by OMNI TEMPLATE, are on the tape in addition to OMNI TEMPLATE. A complete listing of OMNI TEMPLATE and a well- documented manual describing how to use OMNI TEMPLATE is included. HO W DO YOU GET OMNI TEMPLA TE? It is $9.50, if ordered before December I, 1982 It becomes $ 1 4.50 after that. Please add $ 1 .00 for shipping and handling. Send money order or check to: Omni Technology P.O. Box 10630 Pittsburgh, Pa 15235 PA resident please add 57 cents for PA sales tax. each of the two cities. Finding the dis- tance between the two cities would be much easier for the computer if it could Listing 2 8KROM ill ^N^^fSV?^* 1 " 2O0 PRINT "DI5TRNCE="*R Changes for 4K ROM 10 LET L=RNDC100)-1 20 LET N=RND(100>-1 160 LET ftsN/10-L/lB 160 LET C=RtRfB*e 190 IF R<0 THEN LET R=-R S?2 . IF ^ NOT C>R*R THEN GO TO 230 a 10 LET R = R + 1 220 GO TO 200 230 PRINT *'N = ";N."L = ";L 24-0 PRINT "DISTRNCE = "';fi deal directly with the variables N and L. The program in Listing 2 lets it do exactly that. This time, there is no visual map for the human being, but the com- puter can give us the information we want much faster because it is working with a map is designed for it. To get a human-readable version of the map at the same time, combine the two programs into one -none of the line numbers will conflict— and run the result- ing program. In one sense, what we have done in the second program is to elimin- ate all the "white space" from the first map. Only the pertinent information is left. The Real World In most computer games, it is assumed that the whole universe is divided up into squares, and that you always move from one square to the next. This a system lends itself well to simple maps. If you are pretending to fight monsters or shoot aliens, it may work fine, but the real world is not so convenient. Consider an airline route map, for example. You can create a computer map that shows all the territory between cities, but there is not much point in that since airplanes always fly directly from one place to another. All that "white space" just gets in the way. Remember what a map is: simply a group of interconnected places. Suppose you want to make an airline map containing New York and Los Angeles. You might do it like this: Routes: NY-LA: 2800 miles Places: New York (NY) Los Angeles (LA) You might also include another route -LA-NY: 2800 miles. In this case it is safe to assume that the route goes in both directions, but that is not always true. If you were making a map of a plumbing system or a circuit board, it might be important to know which way everything was moving. For now, though, assume that there are no one-way routes. 44 Bigger and Better Of course, there is no reason to limit this map to two cities. Let's expand it as in Figure 2. This looks like a long list of interconnections, but actually it is rather straightforward. In a computer, the important information — the distances— could be represented in a single one- dimensional array which requires far less memory than an accurately scaled visual map. Figure 2. Places: (1) New York (2) Los Angeles (3) Chicago (4) Houston (5) Boston (6) San Francisco Route: (1) NY-LA (2) NY-Ch (3) NY-Ho (4) NY-Bo (5) NY-SF (6) LA-Ch (7) LA-Ho (8) LA-Bo (9) LA-SF (lO)Ch-Ho (ll)Ch-Bo (12)Ch-SF (13) Ho-Bo (14)Ho-SF (15)Bo-SF Miles 2800 840 1650 220 3040 2100 1550 3050 410 1100 1000 2410 1860 1950 3170 The Traveling Salesman Now suppose you are a salesman who has to visit six cities, beginning in one of them and ending in the same city you started from. How can you find the route that requires the least amount of traveling, that is, the route that covers the shortest distance? (This is a variation of the old "traveling salesman" problem.) We find that there are six-factorial possible routes. (Six-factorial, or 6, means 6x5x4x3x2x1, or 720.) Some of these are virtually identical, following the same route but starting in a different city, or running the route backwards. But even after eliminating duplication, there are still 60 different possibilities to choose from. Which one is shortest? You could figure out all the possible routes, if you had lots of paper and lots more time. However, with this map of the six cities, it is easy for the computer to figure out every route and then tell you which circuit is the most efficient. Listing 3 is a program to try all the different routes. The 8K version requires over IK RAM. To use the program on the 4K ROM, make the changes at the end of the listing. The first lines of the program load the distances into the D array. Then P (the current "shortest distance" for the whole circuit) is set very high, and the A array is set up as 1, 2, 3, 4, 5, 6 to indicate a route through New York, Los Angeles, Chicago, Listing 3. 8KROM 1 REH 8800,, 0d4®, 165B . 022©, 304 , 2100 , 1550, 3050 , 04 10 , 1 100 , 1000 , 2410.. 1860, 1950,3170 10 DIM fit?) 20 DIM D(15) 30 FOR D = l TO 15 4.0 FOR fi=16509 TO 16512 50 LET DtD) =10*DR(m THEN GOTO 20 170 NEXT R 180 NEXT D 190 STOP 200 LET fl(N)=fl(N)+l 210 FOR R = l TO N-l HI next'r* =RCN> THEN GOTO a®® 24.0 LET N=N + 1 250 IF N=;7 THEN GOTO 120 260 LET R(N) =1 270 GOTO 210 1000 LET R = 1005 LET R(7)=Rtl) 1010 FOR D=l TO 6 1020 LET O=0 1030 FOR R=l TO 5 1040 FOR B=R + 1 TO 6 1050 LET 0=0+1 tS? - 1 ^** 1 " * n RND R <£> + !> =B OR R (D) =B RND R(D+1)=R THEN GOTO 110 1070 NEXT B 1080 NEXT R 1090 RETURN 1100 LET R=R+D(Q) 1110 NEXT D 1120 IF R>P THEN RETURN 1130 IF RcP THEN CLS 1140 LET P=R 1150 FOR fl=l TO 7 1160 PRINT R(R>, 117© NEXT R 1180 PRINT TRB 8;P 1190 RETURN Changes for 4K ROM 40 FOR Rs 16422 TO 16425 50 LET D (D) =10*D fPEEK (5tD+fi 1 -28 1180 PRINT ,P Houston, Boston, San Francisco, and then back to New York. The rest of the main program simply generates a new route each time, while the subroutine beginning at line 1000 calculates how long each route is. It should only take about three minutes for a ZX80 to come up with the shortest route. Trees It should be clear by now that different kinds of maps are useful for different purposes. For a human being to find the right highway, a road map works just fine. For a computer to solve the "traveling salesman" problem, we saw a better kind of map. A third type that has a very specialized use is the "tree-structured" map. Remem- ber what the defining characteristic of any map is: it represents a group of interconnected things. A tree-structured SYNC Magazine Kiiy.iioxiws I I J o IwJeI R J T J y! U | w i I o I,_p1 t _L I J A I S J D I F |g|h| «3 I Z 1 X 1 C J V | B J |a|5|d|f1 g"1h1j1k|l1 U N I H I . |shut| J WHY BUY A FULL-SIZED KEYBOARD FROM B>mU«l»U-g; M ELECTRONICS T . HAT 5.0ME OF OUR CUSTOMERS >AY ; ARO ATTACHED IN LESS THAW 20 HINUTES AND WORKE! • SERVICE: PHENOMENAL. RECEIVED KEYBOARD IN UNBELIEVABLE UW !HE ORDER. .. .L.B. I KEYBOARD bO MUCH* THAT WHEN I TOLD MY BROTHER ABOUT IT, HE HAD TO HAVE ONE TOO M.V. I WITH KEYBOARD. SPECIAL CIRCUITS PLANS ARC EXPLICIT AND COMPl SEND PARTS KIT L.B. -lY, GOLD CONTACT/ FULL 1.TROKE KEYBOARD* ORIGINALLY MADE FOR A TEXAS INSTRUMENTS COMPUTER TERMINAL. HAS SPACE BAR* 2 OVERSIZED . ■ A.; OVERSIZED RETURN (ENTER) KEY AND 12 SPARE KEYS WHICH CAN BE USED FOR THE SPtCIAL CIRCUITS DESCRIBED BELOW. AN OPTIONAL PARTS KIT IS AVAILAbLE WITH ALL THE ELECTRONIC PARTS REQUIRED. (IC*S, RESISTORS, IC SOCKETS, CAPACITORS, ETC) YOU PROVIDE ONLY SOLDER, WIRE* AND A SMALL PIECE OF PERF-BOARD FOR ASSEMBLY. ARO COMES FULLY ASSEMBLED AND READY TO CONNECT TO YOUR ZX30/81 /M1CRQACE VIA A 13 CONDUCTOR RIBBON CABLE (SUPPLIED). THE EXPANSION CONNECTOR IS LEFT FREE RINTER* ABBITIO rC. EACH KEYBOARD COMES WITH FULL 10 DIAGRAMS FUR THE FOLLOWING SPECIAL CIRCUITS: - allows you to lock the keyboard in tne shifted moae. Simplifies graphics. ivated, you can hold any key ■epeat until released. Makes it easy to n,ove cursors quickly, draw grapnics, aelete words-phrases-! ines. . -you select whi . vou want to place o> keys. Pressing j, . 11 enter the function. The circur ■ elect- a 1 ly .Our parts kit co nta ins enough parts to dedicate 10 keys. OO , L y ASSEMBLED KEYBOARD & PLANS FOR THE SPI Shipping, insurance, handle. ITOfPAU S3 . CANADA $6 . ALL OTHER FOKF I ' Texas residents add $2.53 state Bales Lax. FOR PARTS KIT ADD $13 and at. handling Texas residents add S.72 additional salei Ij>t4>UJ^t^^ M ELECTRONICS |"J| 1?5 LELANI IISI SAN ANTONIO, TX 7B242 ALL PRICES ARE S U.S. AND ONLY U.S. DOLLARS CAN BE ACCEPTED. MONEY ORDER OR CASHIERS CHECK PREFERRED. PERSONAL CHECKS MUST CLEAR BEFORE SHIPMENT. 50 NIFTY 1K PROGRAMS FOR THE ZX81 A large variety of great games, interesting activi- ties, and plenty of graphics, providing hours of fun for the whole family. Also available — 50 nifty programs for your Timex 1000. Same great programs. But upgraded for 2K machine. The result is very user friendly with addi- tional levels of play. $9.95 each includes postage/handling Listings and cassettes available: send sase for free catalogue. JENN PRODUCTS BOX 246 HARRISON, ME. 04040 BASF-DPS WORLD STANDARD TAPE MONEY BACK GUARANTEE PREMIUM S-SCREW SHELL FITS ALL STANDARD RECORDERS COMPUTER GRADE BLANK CASSETTES DATA TRAC / C-05, C-10, C-20 TRACTOR FEED BLANK DIE-CUT LABELS me ec-P-ES* sup* £ ndon *ff£ W K T l" ..,- TV * rKJ YOU'VE TRIED THE REST, ^g> Gr© efTV NOW BUY THe aesT J^ffyQ Toll. OiQaifl ivnn 'or immediate shipment //4fiy^ J*& 9n/7in-iinn onCred)tCard0rdefl tSB ORDER NOW . . . YORK lO Computer wa?^ MAIL TO: 24573 Kittridge St.. Dept. S-2 Canoga Park, CA 91307' ORDER FORM » fTEM 1 DOZEN 2 DOZEN TOTAL C-05 Q 7 50 Q 13 50 C-10 Q 800 □ 14 40 C-20 □ 10 00 G 1 8 00 Hard Box Q 2 50 Q 4 00 Soft Box D 2 00 D 3 40 6 Cap Album @ $6 95 each Quantity _. Blank labels Q 4.00/100 Q 30 00/1000 SUB TOTAL Calif residents add 6% sales tax Sh.pp.ng 1 doz $2. 2 doz S3 50. 3 doz $4 50 each additional doz S 50 For Parcel Post instead ot UPS ADD $1 Outside Continental USA, ADD $2 TOTAL Each cassette includes two YORK 10 labels only. Boxes are sold separately. Ship- ments are by UPS unless Parcel Post requested Boxes, albums. & blank labels are free of shipping charges when ordered with cassettes When ordered separately Minimum shipping is $2.00 PLEASE SEND QUANTITY _ DISCOUNTS D Check or M.O. Charge to enclosed Q Credit Card: □ VISA nMASTERCHARGE Card No. Exp. Name Address City State/Zip Signature Computer make & model SAVE YOUR SOFTWARE $$ $11.95 FOR 4 If you have space problems, PACK!! PACK will store 4500 ( + ) 8 digit entries in 16K. Try to get that anywhere else!! CHART YOUR BUDGET Don't just enter your monthly in- come and expenses, TRACK your progress Year - to- Date. Uses unique PLOT arithmetics and screen layout for each account. Up to 14 accounts and EXPANDABLE' Menu & INKEY driven 16K CLIENT MASTER Do you have clients, friends, credit cards? Hold all infor (Acc#, Tel#, Addr) for each. ADD/DEL/LIST/ CHG/ SEARCH your file in sec- onds. Excellent education in large- scale program management as well. 16K CRAPS — All work and no play makes Jack a dull programmer! Fun for the family. Send check to: OVERBYTE - 902 S.E. 24th Ave, Cape Coral, Florida. 33904 Cassette(s) will be mailed within 3 days. ARTIST ARTIST is a ZX81 (16K RAM) pro- gram that, with more than 30 com- mands, helps create drawings/ paintings on screen. Features in- clude: user's choice of brushes and backgrounds; free mix of graphics and alphanumeric^; easy graphic specification of lines, circles and half-circles; ability to define, store and recreate complex patterns anywhere on the screen; ability to save the artwork on tape or print it. ARTIST is very easy to learn and use. 4-years old kids master its basic commands in minutes. At the same time, advanced features sup- port the creativity of sophisticated users, which can define their own commands; for them, ARTIST of- fers an extensive graphic command language. Cassette and instructions — $10 ($12 outside U.S.). From: KSOFT, 845 Wellner Rd, Naperville, III 60540. map has one additional characteristic : the map begins with a single place (or thing), and exactly one new connection is made for each new place (or thing) on the map. The best way to understand this type is with an example. Let's start out with a map like this: New York True this is not much of a map, but now add some more cities: New York Chicago Los Angeles Notice that the new cities are connect- ed to New York, but not to each other. Why not? Think about the definition of a tree-structured map. It starts out with one place— New York. Then, with each city added to the map, exactly one new con- nection is made. Thus there will always be more cities than connections— exactly one more, in fact. Let's make the map still larger as in Figure 3. Once again, there is just one new connection for each new city. One way of looking at this is to say that each new city connects to exactly one pre- viously existing city. _ Figure 3. New York Chicago Los Angeles St. Louis Peoria Las Vegas Sacramento Shaking the Family Tree How useful can a map like this be? Not very, if you are looking for a road map. Most cities are a little better connected than that. But consider for a moment a family tree. It works exactly like a tree- structured map. For example, Figure 4 Figure 4. Beth David Edna Fred George Henry / \ / Irma Jack Kathleen shows a visual map of a family tree covering four generations. If we consider this tree structure as a map with places and routes (the places are people, and the routes are lines of parentage), it will look like this: Places: Routes: Art Beth Art to Beth Art to Charles David Beth to David Edna Beth to Edna Fred Beth to Fred George Charles to George Henry Charles to Henry Irma Edna to Irma Jack Edna to Jack Kathleen Henry to Kathleen As you would expect in a family tree, each new person is the son or daughter of exactly one person already in the tree. That means there will be just one new connection for each new person; the number of connections is one less than the number of family members. Counting Off Now suppose we give everyone in our family tree a number, beginning with zero, and each family connection a number, beginning with one. Since there is one more family member than connections, we find that the member and the connec- tion have the same number. The result looks like this: Places: (0) Art (l)Beth (2) Charles (3) David (4) Edna (5) Fred (6) George (7) Henry (8) Irma (9) Jack (10) Kathleen Routes: (1) (0,1) (2) (0,2) (3) (1,3) (4) (1,4) (5) (1,5) (6) (2,6) (7) (2,7) (8) (4,8) (9) (4,9) (10) (7,10) 46 Now something else becomes obvious: the second element of each pair matches the route number. Why? Because a tree structure gets bigger by one place and one route at a time. Each new place connects, by a new route, to some pre- vious place. Each new family member is the son or daughter of exactly one pre- vious family member. This map is significantly different from the one we made of the six cities. For that map, we got all the distances into one array, but to do it we used the program- SYNC Magazine ming trick found in lines 1030-1080. The trick was necessary to fit the program into IK, but it is still a trick. With a tree structure, there is no gim- mick involved. We really can represent the entire map in a single one-dimensional array which is a very memory-efficient way of making a very complex and extensive map of a tree. A-Maze-Ment If a carefully constructed map of the tree type be stored as an array, why not stand the process on its head? We should be able to use an array full of random numbers as a maze. We must keep a few things in mind. First, the random numbers have to be chosen within the right range. Remember, every place on a map has to connect, directly or indirectly, with every other place. Second, to keep the maze from being too easy we should scramble some of the connections and add some extra cross-connections to the basic tree structure. A program that does all of these things and puts them together to generate a complex random maze of almost any size is given in Listing 4. The 8K ROM version requires over IK RAM. To use on the 4K Listing 4. 8K ROM 1ft PRINT "NUMBER OF ROOMS'?" 8ft INPUT N 3ft DIM D12#N1 40 POR R=l TO N 5ft IF fi»l THEN LET D «• 6ft IF R>1 THEN LET D tfl> «INT (R NDt(R-l) ) +1 7ft NEXT fi 8ft FOR RaN+1 TO 2 *N 9ft LET D«R)»INT (RND*N)+1 Iftft IF D(R>«R-N THEN GOTO 90 lift IF RND>.5 THEN GOTO 15ft 12ft LET L*Dtfi) 13ft LET D(R) «Dtft-N> 14.0 LET D (fl-N) *L 150 NEXT R 160 LET 0=INT (RND*N) +1 170 CLS 1O0 PRINT "YOU RRE " .; 190 IF O>0 THEN GOTO 220 200 PRINT "OUTS IDE --YOU MRDE IT 210 STOP 220 PRINT •IN ROOM ";Q.;" WITH DOORS . UHICH 230 GOSUB 40ft 240 PRINT 2*N-L; DOOR*?" 2SO INPUT L 26© GOSUB 41ft 270 IF L < >0 THEN GOTO 250 280 IF 0=D(R) THEN GOTO 310 290 LET Q*DCR) 300 GOTO 170 31ft LET Q=R+N*(P>N) 320 GOTO 170 400 LET L=2*N 410 FOR R=l TO 2*N 420 IF R=G OR R=Q+N OR D(R)=Q T HEN LET L=L-1 430 IF L<>0 THEN NEXT R 440 RETURN Changes for 4K ROM 60 IF R>1 THEN LET DtR)aRND(R- 1) 9ft LET D9 THEN GOTO 11 230 IF B=A THEN GOTO 400 300 PRINT A*, , 9 B*, 99 C*, , , B*, , , D * » > , B», , , 6*, , , F*» , , E*, » , B* , , , A* 310 GOTO 500 400 PR INT A*, , , B*, , , C* , , , B* , , , D *, , ,B*, , ? E*, , ,F* f , ,6*, , ,B*, , , AS 500 PRINT 510 PRINT "HIT N/L TO CONTINUE" 600 INPUT H* 610 CLS 620 IF H*="" AND NOT B=A THEN G 0T0 110 630 IF H** Mn THEN GOTO 100 640 STOP 10 LET A$= "AAAAAAAAA n 20 LET BS» ,I A######«A > " 30 LET C*«"A#DD#DD#A" 40 LET D** ,, A##261##A" 50 LET E*="A#D###D#A" 60 LET F*^"_A*^£#_D^#A_" 70 LET B*« n £#tt*D##*A N ■ LET A- 1 NT (RND*9)+1 110 PRINT "HOW MANY BLOCK 1 15 pr nil R 1=1 10 A 1 30 PRINT "j5#"; J. 40 NEXT I i [NPU1 B CLS ' THEN BOTO 3. 10 230 IF B=A THEN GOTO 400 300 PRINT A*, ,B*, , C*, , B*, ,D*, , B $, ,B*, ,F*,,E*, ,B*, ,A* GOTO 500 400 PRINT A*, , B*, , C$, , B*, , D*, , B *, ,E*, ,F*, ,G*, , BS, ,A« 500 PRINT 510 PRINT "HIT N/L TO CONTINUE" 600 INPUT H$ 610 CLS 620 IF H*» ,,M AND BOA THEN GOTO 110 630 IF H*="" THEN GOTO 100 640 STOP ZX81 the BEST yet from M.C. Associates PELOPONNESIAN WAR — a brand new 16K game Your ultimate goal is a final victory over the Spartans but you will need to deploy all your skill in a combination of diplomacy and military force before you even stand a chance! Price $14 also TYRANT OF ATHENS (16K) Price $14 ROMAN EMPIRE (*16K) Price $14 Buy more than one cassette and deduct $1 from the price of each. Cheques or IMO's please — made payable to: M.C. ASSOCIATES 4 GRANBY ROAD, CHEADLE HULME CHESHIRE SK8 6LS U.K ZX81 16K LOTHLORIEN COMPUTER GAMES New release Warlord Price $14 A16K game set in 13th Century Japan • Can you rule a warring village to survive for 30 years? • Can you defeat the armies and samurai of other warlords? • A challenging game where all results are dictated by your own decision. ''SAMURAI WARRIOR" Could you survive in 13th century Japan? (16K) • In combat with other Samurai • Fighting bandit groups • Assisting villages or will you commit ritual suicide? Become engrossed in this game of skill for only $14 Buy both for just $25 Cheques or IMO's please — made payable to: LOTHLORIEN COMPUTER GAMES 94 Flixton Road, Urmston, Manchester M31 34D U.K Get the most from your SINCLAIR with these practical, program-filled books from Syncl Getting Acquainted With Your rvvoi £j-/YO± and ZX81 Z x80 TheZX81 Companion The Gateway Guide to the • R t*J T ime G r aphics • Information Processing • Educational Application! The ZX81 Companion by Bob Maunder The ZX81 Companion follows the same format as the very popular ZX80 Companion, and assists the ZX81 user in four applications areas: graphics, information retrieval, education and games. This practical guide contains scores of fully documented short rou- tines plus complete programs and a dis- assembled listing of the ZX81 ROM Monitor "Thoughtfully written, detailed, and illustrated with meaningful pro- grams."— MUSE 5 Vi" x 8", 132 pages. #17P $8.95 ($2.00) Second Edition More than 80 Programs More than 70 Programs Getting Acquainted With YourZX81 by Tim Hartnell This informative volume for the new ZX81 user contains more than 70 pro- grams to help the reader get the most from his Sinclair computer Game programs include Checkers, Alien Imploders, Blastermind, Moon Lander, Breakout, Star Burst and Derby Day The book also shows programs for cascad- ing sine waves, plotting graphs and tables, data sorting, equation solving, plus the use of PLOT, SCROLL, PRINT TAB, PEEK, POKE and much more! 5 V 2 " x 8", 120 pages. # 15Y $8.95 ($2.00) The Gateway Guide to the ZX81 and ZX80 by Mark Charlton The Gateway Guide is a practical pro- gramming manual for the beginner that furnishes over 70 fully documented pro- grams. The majority of the programs have been written for easy conversion from machine to machine (ZX81, 4K ZX80 or 1 K ZX80). The Gateway Guide describes each function and statement, illustrates it with a demonstration rou- tine or program, and combines it with previously discussed material to help you understand your computer. 5V 2 " x 8", 172 pages. #160 $8.95 ($2.00) Computers for Kids (Sinclair Edition) by Sally Larsen This new edition of Computers for Kids is written specifically to introduce children aged 8 to 13 to the ZX81. The book requires no previous knowl- edge of algebra, variables or computers, and it enables a youngster to program a ZX81 in less than an hour. There's also a section for parents and teachers. "Computers for Kids is the best material available for introducing students to their new computer." —Donald T Piele, Professor of Mathematics, University of Wisconsin-Parkside. 8V2" x 11", 56 pages. #12S $3.95 ($1.00) AH volumes are softbound. r Creative Computing Press, Dept.Z020, 39 East Hanover Ave., Morris Plains, NJ 07950 ^ Please send books listed below: □ Enclosed is$_ . NJ residents add 5% sales tax. Item No. Qty Price each (P&H) Total Price Postage and handling charges appear in parentheses ( ) next to price of book □ Charge my (Charge and Phone Order $10 minimum): D American Express □ MasterCard □ Visa Card Number- Signature Exp. Date- Mr Mrs. /Ms.- Address — (please print full name) . MllfJ Outside USA add $3 00 per order- shipped air mail only City State/Zip- CHARGE ORDERS-For Your Convenience PHONE TOLL FREE 800-631-8112, In NJ. Only (201) 540-0445. J CHIRPER module for your ZX81 The CHIRPER module lets you enter keyboard data fast and accurately. A sound can be heard when a key has been entered enabling you to spot a double entry or missed entry without looking up at the screen. The CHIRPER sound is produced when a pro- gram runs. A key entry results in a buzz-like chirp on 1 K or 2K machines. Large programs in a RAM pack produce a continuous sound that chances pattern on key entry The CHIRPER module installs easily inside the 2X81 case with only 3 wires to connect. Complete installation instructions included. ToorderyourCHIRPERsendacheckormoney order. We pay the postage in the U.S.A., else- where include first class postage for three ounces. 3584 Leroy, Ann Arbor, Ml 48103 $ Keyboard Audio Tone Audio Keystroke and Program Monitor * TWO TONE One to indicate initial press of key, the second tells you when computer is ready to accept next entry (very useful when entering long pro- gram listing) * Indicates start and finish of running programs, and start and end of SAVE and LOAD routines * Indicates Keyboard entry dunnq INPUT prompts * Use to indicate progress of running programs, or for sound effects in games programs, by including short PAUSE in listing. * Operates in FAST and SLOW modes, with normal or shifted keys * Only five simple connections to 2X81 P.C.B. Supplied ASSEMBLED complete with fitting instructions $18.00 ASSEMBLED. Includes post- age/shipping. Cheques and money orders payable to: TV SERVICES OF CAMBRIDGE LTD CHESTERTON MILL FRENCH'S ROAD CAMBRIDGE CB4 3NP ENGLAND. Tel (0223)358366 8K ROM; 2K RAM 4K ROM; IK RAM Elimination A Dan Klyver Elimination is a traditional dice game which provides a worthwhile vehicle for teaching young children (and others) simple strategy, an understanding of odds, and the mental manipulation of numbers. Consequently, it helps reinforce arith- metic skills since the player's ability to use mental arithmetic is pitted against the computer's problem posing ability. Although the game is fun to play alone, a group can play by each taking a turn and keeping score to see who can do the best job of eliminating numbers. Enter the program in Listing 1 and hit NEWLINE. The numbers 1 to 9 will appear together with the randomly pro- duced results of a dice roll. You are prompted to make a choice(s) of which number or numbers you wish to eliminate in the range of 1 to 9. See Figure 1. The total of the numbers selected for elimi- nation must equal the total of the dice role. For example, if on the first roll of the game, you roll a 5 and a 4, you may eliminate a 9 or any combination of numbers totaling 9. The object of the game is to eliminate all of the numbers. The selection of a given number or combination of numbers is up to the player, but the odds of rolling any particular number should be consid- ered when making the selection. After making the selection, hit NEWLINE. The selected numbers will become zero(s). This will indicate that they have been eliminated and cannot be played again. The results of a new dice roll will also be displayed. The game proceeds with the next selection. Improper entries will result in early termination of the game (a penalty for making a mistake). When the game is approaching the end, a roll that is not compatible with the remaining numbers will terminate the game with the total of the remaining numbers being displayed as the score. The lowest number wins. To play again, hit NEWLINE. To revert to the program listing, enter four letters and hit NEWLINE. After a "win" is scored (all numbers eliminated), the program will be listed again. A. Dan Klyver, 29 Old Stagecoach Rd., Weston. CT 0688.1 4K ROM Version The program listing is for the 8K ROM, but it can be adapted to the 4K ROM by making the following changes: 110 RANDOMISE IS© LET X=RND(6) 140 LET Y=RNDt6> i52 E5 XNT "ENTER YOUR CHOICE tS) ONE RT R TIME ERCH FQLLOUED B Y ENTER" 200 IF NOT B CQ> =© THEN GOTO 2"?© 220 IF NOT B(R>=R THEN GOTO 270 i£2 5E ttSX s =BtS) THEN GOTO 270 f£2 £E^i? T Ts= B THEN GOTO 270 HIT ENTER" " GRME OUER * TO R E p *-RY 450 IF NOT B(R)=e THEN GOTO 50 Listing 1. Elimination (8K ROM). 'ENTER YOUR CHOICE l* S) TIME Ef\CH FOLLOWED B 10 DIM B(9J 20 FOR A = l TO 9 30 LET B (fi.l =R 4-0 NEXT R 50 PRINT "THE NUMBERS TO BE EL IMINRTED ARE" 50 PRINT 70 FOR R = l TO 9 80 PRINT B CR) ; " " ; 90 NEXT R 100 PRINT 110 RRND 120 LET X = INT (RND*6> +1 130 PRINT 140 LET Y=INT +1 150 LET Z=X+Y 1S0 PRINT "YOU ROLLED R ";X;" R ND R ";Y 170 PRINT 180 PRINT ONE RT R Y N/L" 190 INPUT O 200 IF BfO) OO THEN GOTO 270 205 IF Q=Z THEN GOTO 420 210 INPUT R 220 IF B(RX>R THEN GOTO 270 225 IF R+Q=Z THEN GOTO 410 230 INPUT S 240 IF SoBfS) THEN GOTO 270 245 IF Q+R+3=Z THEN GOTO 400 250 INPUT T 260 IF T<>B(T) THEN GOTO 270 255 IF Q+R+S+T=Z THEN GOTO 390 270 PRINT 250 LET U=0 290 PRINT 300 FOR P=l TO 9 310 LET U=U+B(P) 320 NEXT P 330 PRINT "GRME OUER, TO REPLRY HIT N/L" 340 PRINT 350 PRINT "5CORE=";U 360 INPUT G$ 370 CLS 380 GOTO 10 390 LET B (TJ = « 4-00 LET B KS) =0 410 LET B (RJ -0 420 LET B COJ =0 430 CLS 440 FOR R=l TO 9 4.50 IF B(R><>0 THEN GOTO 50 460 NEXT R 470 PRINT "YOU UIN" Figure 1. Sample Run. . rHE NUMBERS TO BE ELIMINATED ARE 300800OS0 /OU ROLLED PI t AND Pt 1 -AME OUER, CRE=8 TO REPLAY HIT N.-L 54 SYNC Magazine 8K ROM; IK RAM 4K ROM; IK RAM Arithmetic with a Smile George J. Repicky The computer as an instructional tool is perhaps nowhere more successful than in conducting arithmetic practice drills. Unlike the typical classroom teacher, the computer never tires and never makes a mistake. It provides arithmetic practice and never forgets to reward a right answer with a smile. Addition Enter the program in Listing 1 and then RUN it. This is the basic program. It will generate an addition problem and print it in the upper left hand corner of the screen. The computer then awaits the user's answer. If the answer is correct, the complete problem with the correct answer is displayed, and the user is re- warded with a smile. After a five second pause a new problem is displayed. If the answer is wrong, the problem is again displayed along with the incorrect answer. The user is again asked the question while a frown is displayed. Entering a letter instead of a number will stop the program. ListinR 1. Addition Practice. lie 120 13* 14.0 150 160 170 180 190 200 210 220 230 24.0 250 260 270 280 2<90 300 310 320 339 34.0 350 360 3 70 38© RflND CLS L ET X = INT I RNr* # 1 > LET V = INT (RNt>*10) PRINT PRINT X, " + " , V , " = ?" INPUT Z CLS PRINT print X; " + ";r;" ■ ";Z FOR N=l TO 20 PLOT I0*5IM tN**->I/10J +31, 1€> (N»FI,'ie.i +22 NEXT N PLOT 26 , 26 PLOT 36,26 PLOT "31,22 PLOT 31,17 PLOT 30,17 PLOT 32,17 IF Z<>X+Y THEM GOTO 350 PLOT 29,13 PLOT 33 , 13 PRUSE 250 GOTO 120 PLOT 29,16 PLOT 33 , 16 PRINT GOTO 150 Other Arithmetic Operations The other arithmetic operations can be done with the following modifications to the program in Listing 1 : Subtraction 140LETY=INT(RND*X) 160, 200, 300: Change + to-. Multiplication 160, 200, 300: Change + to *. Division 130 LET Y = INT(RND*9)+1 140 LET X=INT PRINT , "tt#E##tt##E n 250 PRINT , "#£#######£" 260 PRINT , "£#R####R##D» 270 PRINT 2SO PRINT , "Etttt##E####E " 290 PRINT , "D", "##D" 300 PRINT , " ####"$ 310 IF NOT Z = X + Y THEN GO TO 340 1 PRINT CHR*<156) ; "UJE" 330 GO TO 370 340 PRINT "FW" 350 PRINT , M #E##E#E##E" 360 REM 370 PRINT , "#E'\ "#E_" 380 PRINT , ' ' # #EF #DF #E_' ' 390 PRINT 400 IF NOT Z = X+Y THEN GO TO 160. 410 INPUT I* RUN 7. Subtraction 140 LET Y=RNLMX+1 > - 1 160, 200, 310, 400: Change the^ + to - Multiplication 160, I 0, 400: Change the + to * Division LET Y«RND<9) 140 LET X= 132 PRINT 133 PRINT TRB 8; "NO" 134 IF K=l THEN PRINT U CL-1) J " . ,UtL) 135 IF K = l THEN GOTO 170 136 LET K=l 14-0 GOSUB 600 145 GOTO 120 150 GOSUB 500 155 PRINT G(1);".";G(2) 160 PRINT 165 PRINT TRB 6. "YES" 170 PRINT "N/L FOR NEU SERIES" 175 INPUT tt$ 180 IF «$ = "" THEN GOTO 20 185 STOP 500 CLS 505 FOR 1=1 TO L-2 510 PRINT U (I) j ","; 515 NEXT I 520 RETURN 600 PRINT " INPUT ";L-1;"TH NU MBER" 605 INPUT G(l) 610 PRINT " INPUT ";L;"TM NUMBE 615 INPUT G(2> *20 RETURN Listing 2. Changes for 4K ROM 20 LET R=RND(100> 30 LET H=16426+RND(197) 35 IF PEEK (H> =63 THEN GOTO 50 55 IF PEEK IMJ =63 OR PEEK«11 8 THEN GOTO 95 75 LET U (L) =PEEK (M) -28 +R 133 PRINT , "NO" 165 PRINT , "YES" blocks starting with Z which is used as a flag to tell the computer where each block begins. Line 30 randomizes which block of data is to be used. The computer then searches for the beginning of the block in line 35. A constant is added to the series to make the program more challenging. The end of each block is flagged by the Z of the next block or by 118 (NEWLINE) which is the end of the REM statement. The series is printed on the screen except for the last two numbers which the player has to figure out. The program is packed tightly in IK RAM on the ZX80 and requires over IK RAM on the ZX81. Memory is saved by using keyboard commands in lines 170, 600, and 610. In this way the program provides the maximum variety of series in the small memory. To exit the program, key in a unused variable letter when asked for a number, or key in a character when "N/L FOR NEW SERIES" is printed. Enter the program in Listing 1. If you have the 4K ROM make the changes in Listing 2 as you enter the program. Hit RUN and ENTER, and stretch your arith- metic perceptions. S 4 , 40.42 ,44 .44 .46 .,48, IMPUT STH NUMBER UT 3TM NL/N6ER 56 SYNC Magazine •81 SPACE RAIDERS TM ZX81 ■^ FR= 3 292 E 05 6E = 1 297 E 03 TX = B 275 E 05 TY= 1 182 E 07 TZ = 4 780 E 06 X ~ 5 222 E 05 Y = -2 574 E 05 Z = 5 692 E 06 ^A 16K RAM The Federation has declared a state of all-out war, leaving you in charge of the Starship Defiant: newest and most advanced spacecraft known to man. Soon, your experienced guidance will bring you within range of the Klingon convoy. Hundreds of stars flash by as you check the status of your Phasors, Shields, Masking, Navigation, Scanning, and Computation Equipment. The energy drain is tremendous, as the target distance indicator ticks slowly downward... As you come into range you set your cross-hairs on the nearest ship. Fire Phasors! ! ! Switch to Aft view! ! ! Evasive Maneuvers! ! ! Space explodes all around you as the first Klingon ship disintegrates and the remainder lock onto your position... High speed graphics and custom ML math package provide the real time, accurate simulation of the above space navigation and battle scenario. You've never seen this kind of performance on your ZX81 before! Only $19.95 for cassette, keyboard overlay, and manual (shipping included). (Utah residents add $.95 tax) NIRAD ELECTRONICS 959 East 460 South Provo, UT 84601 ZX81 PERSONAL BANKING SYSTEM WITH LOAD/SAVE DATAFILES AT DOUBLE SPEED Load the program m the normal way — enter, amend or delete your transactions (2X81 will automatically scan standing order file and post any items due)— save the file of data onto cassette in 45 seconds — load a different datafile into the same program, also in 45 seconds — enter items, etc. — save datafile only onto cassette (45 seconds) — repeat operation for any number of accounts Absolutely no need to save program, as all information is held in data- files. Very easy to use — unlike other bank accounts Requires a mini- mum of 16K RAM — can use much more (no modification required) On Demonstration at the next ZX Micro Fair. The personal Banking System also includes the following features — Full page detailed Bank Account, dual display (or printout). Automatic generation of standing orders on due dates. Validation of all entries. Correct any item previously entered (Single/Multiple field correc- tion) Enter an item (previously omitted) in the correct date order of the account. Single key operation Utilises a M/C keyboard scan Search for any item or items by cheque number, description or amount — display (and printout if required) with totals Continuous display of statement extract, continually updated dur- ing input of e n try File of standing order details can be displayed, printed, added to. cancelled and amended. Detailed User Manual. After sales maintenance. Send £9 95 (S20) mcl for cassette and users manual to J.P Gibbons A.I.B. 14 Avalon Road. Orpington. Kent. BR6 9AX. England (Send large S, A. E. for details). There are only two suppliers of supported ZX81 software, thts is one of them Be sure to include your name and address Coming soon: Bank Reconciliation Module — a separate program on cassette that utilises data supplied by the main program (S.A.E for full details) The only expandable system for the ZX81 The Personal Banking System is also available from the Buffer Shop. Streatham, London and Branches of the Computer Bookshop Group, full maintenance still available from Scramble r j Supplied on cassette with library case ONLY $7.95 The high-speed arcade game. Easily the fastest available. 32 zones, thrust and altitude controls. Other great ZX games and add-ons from Mikro-Gen: Space Invaders the best you can get, with ever-increasing rate of play Breakout with seven bat angles to make it really difficult Bomber positively addictive A/D Converter Board Lets you connect analogue joysticks to the ZX81 digital inputs. Suitable for many other applications, easy to con nect - and it improves RAM pack stability! ONLY $36.95 Joysticks Connect via our A/D Board - makes your ZX81 a true programmable games machine ONLY $18.95 EACH Disassembler/Monitor An absolute must when learning machine code - lets you enter and run your own code ZX Chess The original-and still the best! Sorcerer's Castle takes you into a world of magical adventure . .ill supplied on cassette with libra- . $7.95 each (ZX Chest $12.95) ONLY $7.95 Write tor full details of the Mikro-Gen range of programs and add-ons, available from local stockists or direct from the manufacturers (please make cheques/PO's payable to Mikro-Gen and add $1.90 postage for software, $3.50 for hardware Suppliers of Software to Smcia mjlr>^ 24 Agar Crescent Bracknell Berks RG 1 2 2BK Tel: Bracknell (0344) 2731 7 8KR0M IK RAM Solving Implicit Functions on the ZX81 Basil Wentworth Solving arithmetic and algebraic prob- lems on the ZX81 is easy when the variable wanted is defined explicitly, that is, if you know that Y = X ** 2 + 2 * X, it is easy to program: 10 INPUT X 20LETY=X**2+2»X 30 PRINT Y Now you put in the values of X and let the computer find the corresponding values of Y. The fun begins when the variable you want is defined as an implicit function. Suppose, for instance, you have a value of Y for the above equation and you want to find the corresponding value of X. As a practical example, let us define a rec- tangle with an area of 15 square feet subject to the constraint that the length will be two feet greater than the width. This would give you the exact equation shown above, i.e., 15 = X * (X + 2) or 15 = X**2 + 2*X. This is a little hard to program. Just try telling your computer to LET 15 = X ** 2 + 2*X. In your high school algebra class you learned some fairly easy ways to solve a quadratic equation and that is what we have here — if you remember them. But what is the use of having a computer if you are going to solve the problem by the old horse-work techniques? Or, suppose, you get something a bit more complicated like Y = X ** 3 + 3 * X ** 2 + 4 * X. Or, perhaps, Y = X * SIN X. Or, Y = (e ** X) * SIN X. It is a little harder to solve these. The computer can handle problems of this kind by making a series of successive approximations: try out any value of X, and see if it gives the Y you want; if it does not, then try another value of X. Basil Wentworth. 1413 Elliston Dr. Bloominuton IN 47401. This is the sort of thing that a computer does beautifully, but you will want to give it a little guidance. If you keep pulling X's out of the hat, you may never hit on the right one; in fact, you may not even know how close you are to being right. So you want to find a systematic way of zeroing in on the right value of X. . Figure I. Graph of Y = X**3-9*X**2 + 26*X 58 SYNC Magazine STOCK MARKET PRICE ANALYSIS HELPS for the Small Investor Now SINCLAIR ZX-81 (16K) owners can do what the professional market traders do — use a computer to predict price direction This program tracks up to six stocks, averages, or commodities, and produces graphs and uses technical indicators to help you make trades Technical analysis is based on two ideas first, that the market, like the rest of human behavior, repeats itself; and second, that there are professionals and in- siders who know what the market is going to do before everyone else does, and who place trades in a way that is hardly noticeable TECHNICAL ANALYSIS attempts to read the pnce action and volume figures to determine whether predicable patterns are developing, and what the professionals are doing Professional traders have been using computers to make this kind of analysis for years, because the manipulation of the data is very complicated and time- consuming. With this program, you let the computer do the work, and its signals become a powerful investment tool The program makes GRAPHS of the daily prices, of two moving averages, and of a volume indicator A booklet that comes with the program helps you learn what to look for The program does an ANALYSIS to signal trend-formation and turnarounds It gives a score for each indicator, and a total score, to help you see whether there is confirmation among the signals. USE THIS TO TRADE STOCKS, OPTIONS. AND THE NEW STOCK INDEX FUTURES!! This gives POWER TO THE SMALL INVESTOR! For program tape and booklet send $30 00 to MOOTER STOCK PROGRAM 320 East 25th Street New York, N.Y. 10010 (NY residents, add $2.48 sales tax.) THE BEST VALUE NEXT TO YOUR COMPUTER IS SUPPORTED SOFTWARE ON CASSETTE 2X81 MX-PAC Tsiooo 18 useful/fun programs on CASSETTE make the small memory act like much more-for the whole family .. games . . files. . lists. . SUPER draw-on-tv, se- curity codes.. 3-D motion and growth simulations. .bar graphs. .financial helpers (loans, tax) + more +all BASIC ..all explained in Printout 1.. . and 1 extraordinary BOOK , Printout 1 shows how the 18 work and GROW and .even more line- 2K and 16K GROW - .many ideas. numbered add-ons for power -multilevel files , lists, games . . a keyboard "light-pen" that makes draw-on-tv a powerful designing tool - menu-driven programs-f inane ' 1 planner . . a complete recipe file (16K) . . step by-step build a checking account (16K) -"unbreakable" codes and a challenge THE GREATEST RANGE AND DEPTH OF ANY SOFTWARE is only $24. 95.. Act today! Send check or MO to ROBILL PRODUCTS 555 PARK AVE. ,PATERSON,NJ 07504 ALL ORDERS processed fifo. Please add $2.75 p/h (1st class)NJ res. add 5% EDUCATION ENTERTAINMENT Personal Management 1 6K Software On Cassette ZK-PARTY GAMES $9.95 Five Games for Hours of Party Fun. Includes Charades (500 topics), Password (500 words), Improv-Skits, Gossip, and "Radio DJ' . PARTY GAMES FOR CONSENTING ADULTS $14.95 Contains five games designed to entertain a gathering of close friends. Strip/Trivia, pits your knoweldge of trivia against your clothes. In "Body Twister" the com- puter tells players where to place their hands, feet, etc. on other players. Three others. Write for information. ZK FOOTBALL $12.95 This textual version of football features 1 2 off. players, 8 defenses, solitaire or dual plays, auto time keeping, individually designed teams, and full team stats (includ- ing printer output). Plastic keyboard overlay. ZK BASKETBALL RELAYS (AVAILABLE NOV. 1.) Teams include 8 individually rated players who shoot, rebound and defend as in real life. Solitaire or two play- ers, 1981 /82 Pro (23 teams) or College Top 25. $19.95 each. PRIMARY ASSOCIATION $9.95 A good way to introduce your three-six year old to com- puters, while reinforcing school work. Provides drills for matching, association, and basic comprehension. ARITHMETIC BASEBALL $9.95 An entertaining educational program where children and adults compete evenly while learning. Questions range from simple counting to trig. Correct answers result in hits according to relative difficulty. HOME MANAGER $12.95 This menu driven program stores info on 50 families (enough for most) on each cassette. Names, address, phone, and four lines of miscellaneous data (up to 8 important dates). Sort on names or dates. Also includes printer output for address labels or complete files. WE OFFER A COMPELTE LINE FOR EDUCA- TIONAL, GAME, HOME AND PERSONAL MANAGEMENT PROGRAMS FOR THE ZX81 AND TIMEX 1000. CATALOG $1.00 CREDITED TOWARD FIRST ORDER. ZOR KHAN INDUSTRIES BOX 31567 Aurora, Colorado 80041 Full replacement warranty on all tapes. Add $1.00 postage and handling. Colorado residents add 6.5% tax. Send check, money order, or VISA-MASTER CARD Acct. #, Exp. Date, and Signature. No COD. Please. Z-Ware Sale ZX8 1 /TS- 1 000 Software on Cassette $8.95 each ppd. 1 6K Histogram — plots bar chart 1 6K Financial Manager— for home or business 16K Machine Intelligence Demo — life forms that actually learn. Many more available — send self-addressed, stamped en- velope. Z-Ware Box 111 Albany, Kentucky 42602 1-606-387-8391 WARP IO A graphics space game, for the ZX8 1 with ten different skill levels requiring 16K. Only S9.95. Send S9.95 plus S1 50 for postage to: SOFT CLAIR Two Enchanted Oaks Orange, Texas 77630 E^ *»» +# #» » »» »++ +# +» » +# +— » # » — * STATS IN A FLASH Sinclair COMPU-STAT 8K/16K. Menu-driven program with user's manual does common descriptive stats plus student's f, Mann-Whitney U. Simple ANOVA Automatic freq. dist. graphing. Also ZX-printer output _ SAVEs & LOADs data on tape $9.95 for cassette and J | user's manual from: COMPUTEHCRAFT 156 Drakes « > Lane. Summertown, TN 38483 Sinclair Computer Family SOURCE BOOK Find out what your Sinclair Computer can do! Contains over 600 programs, books and accessories for the: T5-100CUZX-81 ZX-80 • Miao-Ace Send $6.95 plus $1 .25 postage/handling. Atlantic Computer Products Post Office Box 936 Norfolk, Virginia 23501 60 Linear Interpolation The method for doing this is called Linear Interpolation. Look at Figure 1 for a moment. Suppose that the solid curve shows the relationship between X and Y and that the dotted line indicates the value of Y that you are interested in. The value of X that yields this Y is found, of course, right beneath the point at which the dotted line hits the curve— somewhere between XI and X2. So select XI and X2 as first approx- imations, find what values of Yl and Y2 they correspond to, and then go for another estimated value of X according to what Yl and Y2 tell you. The adjust- ment in X will not be strictly proportional to the error in Y unless the curve is a straight line in this region, but a pro- portional correction will still get you closer than you were, although on rare occasions you will come across a function that defies solution this way. Then use the new value of X as the approximate solution, and go through the process again, and again, if necessary, until you have reached the degree of accuracy you want. Choosing your first XI and X2 so that Yl and Y2 surround the value is not usually imperative, but this can be helpful. In most cases, any two arbitrary approx- imations (as long as they are equal to each other) will suffice although some take longer to run than others. Listing 1 contains the program to use. Type it in; press RUN and ENTER. The computer will ask you to enter the state- ment of the equation as Line 40. For example, the equation cited above would be entered as 40LETY=X**2+2*X Then RUN 60 as the program instructs. The computer then tells you to enter a couple of guesses for X, as well as the target value for Y. Then, as instructed, enter some toler- ance figure to define the degree of accuracy that you want in the answer. Be realistic. If you ask for tolerance, the computer will run all night seeking the impossible. If you specify 10% the com- puter will probably come a lot closer than 10%. If you call for .01%, the error seems Listing I. Implicit Functions (8K ROM). . *0 LET Y=F 10 PRINT "ENTER X) " " " 20 PRINT 30 PRINT "THEN RUN 60" 50 RETURN 60 PRINT 70 PRINT "ENTER Y" 80 INPUT Y0 90 CLS 100 PRINT 110 PRINT "ENTER FIRST APPROXIM- ATION TO X" 120 INPUT XI 130 CLS 14-0 PRINT 150 PRINT "ENTER SECOND APPRO XZ NATION TO X" 160 INPUT xa 170 CLS 180 PRINT 190 PRINT "ENTER TOLERANCE IN P f-ZRCENT" 200 INPUT T a 10 CLS 220 PRINT 230 LET X=X1 24.0 GOSUB 4-0 350 LET Y1=Y 260 LET X = X2 270 GOSUB 4.0 280 LET Ya=Y 290 LET X3=(Xl-X2)*(Y0-Ya)/(Yt- Y2) +X2 300 LET Xl=Xa 310 LET X2=X3 330 IF ABS (100*(X1-X2)/X1) ;T HEN GOTO 3 10 330 PRINT "X = " ; X.2 usually to fall in the range of .001% or less. This is close enough for most practi- cal purposes. In fact, you may want to "hard-write" (as an analogy with "hard- wire") a tolerance limit of .01% or .001% instead of entering it each time. Limitations This technique has one limitation that may be serious in some instances. Many equations have two or more solutions, but this approach will give you only one of them. In the example given, the two solutions are: X = 3 and X = -5. In the practical cases, you are interested only in the positive values since it is rather difficult to lay off a length of -5 feet. And, if you started out with positive values for your approximations to X, the computer will give you the positive answer, but you run into trouble if more than one solution is realistic. The curve shown in Figure 1, for example, represents the equation Y = X ** 3 - 9 * X ** 2 + 26 * X. If Y = 24, the equation has three positive roots: 2, 3, and 4. This routine will give one or another of them according to the approx- imate values chosen as the points of departure. If it were not for this factor, entering "hard-write"' values for XI and X2 in lines 120 and 150 would be tempting. SYNC Magazine Another caution: do not make your first approximations too small. Above all, do not use zero. Even if you expect your answer to be zero, it is better to start with numbers like 1 or 2 to reduce the possi- bility of running into numbers too big for the computer to handle in line 260. One other danger to watch out for is in the handling of negative numbers. Remember that the ZX81 is not able to raise negative numbers to powers. I sus- pect that this is so because the computer uses logarithms in the process, and the logarithm of a negative number baffles computer and human alike. If this danger appears to be imminent, it can be avoided by the following substitutions: For even-numbered exponents, replace X ** n by (ABS X) ** n. For odd-numbered exponents, replace X ** n by SGN X * (ABS X) ** n. Remember that it is very, very likely that you will run into negative numbers when you use trigonometric functions. The same strategem will work with them. For even-numbered exponents, use (ABS (SIN X)) ** n. For odd-numbered exponents, use SGN (SINX)*(ABS(SINX))**n. The program can be translated to the 4K ROM by making the following change: 10 PRINT "ENTER#";CHR$(212);"#40 LETY=F(X)";CHR$(212) However, the program will lose some of its appeal because of the lack of floating point arithmetic. The answers will be in whole numbers so the closeness of the approximations will be lost. One final limitation is that this routine will not give imaginary roots, i.e., square roots of negative numbers, designated by mathematicians as i and by engineers as j. But you have little chance of running into these unless you are working with AC power or electronic circuits. One final caution, remember that the ZX81 gives you the arguments of trigono- metric functions in radians. If you want degrees, multiply the radian value by 180/PI. (Ed. -See the article "Degrees, Grads, and Radians" elsewhere in this issue. ) H or TIMEX 1000 Extend your ZX81 System: Add Memory that won't Forget! *» ADD YOUR OWN SYSTEM UTILITIES * BUILD UP A LIBRARY OF MACHINE LANGUAGE SUBROUTINES UP TO 8K NONVOLATILE RAM USE HM6116P CMOS RAM + OR 2716/2732 EPROM ** LOW POWER BACK-UP COMPATIBLE WITH 16K RAM PACKS This memory board is designed to fill the transparent 8K block of memory (from 8 to 16K) in a ZX81-16K system The use of HM6116P 2K CMOS RAM memory IC's with their own reserve power supply means that routines stored in the RAM are nonvolatile — the RAM retains its memory even when the ZX81 is switched off or reset. Moreover, be- ing RAM. the routines you store in the memory are easily modified With this board it's no longer necessary to place your machine language routines in REM statements, in string variables, or beyond RAMTOP. You can build up a resident library of machine utilities for use by your BASIC system. Complete step- by-step instructions m a 14 page manual make assembly of the board easy. Construction takes be- tween one and two hours The kit (pictured above) is com- plete with a silkscreened solder-masked printed circuit board, all capacitors, resistors, transistors, sockets, con- nectors, integrated circuits, and the lithium cell. The board is supplied with one 2K CMOS 6116P-3 RAM — it will ac- comodate three more for a total of 8K Send check or money order for $29 95 plus $1 95 shipping and handling to the address below. The printed circuit board with the instruction manual is available separately for S1 5.00 post paid. HUNTER, 1630 FOREST HILLS DRIVE, OKEMOS, MICHIGAN 48864 H ZX80 ZX81 TIMEX MICROAGE CRASH NOT. WANT NOT. Have you had unexplamable system crashes'? Lost programs due to brownouts or power failures 7 Or just plain tripped over your electric cord 9 If SO, you need an unmterruptable power supply. UPSy STEMS is a battery powered backup system that kicks in automatically as soon as its sensors detect a drop in voltage coming from your power supply Your system keeps on ticking Simple to install and use Just plug your power cord into UPS and plug UPS into your system and you are ready for any power glitch or failure (Additional cord included) All systems include on/off/reset switch for your convenience (you no longer have to unplug your computer to reset it) All systems are compact, ap- prox. I3cmx 7cmx 4cm(5'e x2Vx IV). UPS-1 Economy system, uses 2-9 volt alkaline batteries (not included) $14 95 * S2 00 shipping, handling & insurance UPS-1M Same as UPS-1 except it includes a Pro- gram Loading Monitor to solve your tape loading problems $19 95 * $2 00S.H&I UPS-2 NiCd system that recharges itself auto- matically (NiCd batteries included) $29.95 • S3.00S.H&I. UPS-2M Same as UPS-2 except it includes a PLM $34 95 ♦ $4 00 S. H&l 90 Day Guarantee on Parts and Labor Check or money order payable to UPSystems Foreign orders add $1 00 UPSYSTEMS RA BANKS 5800 HOLLISTER DEPT1901 HOU TX 77040 ARTIFICIAL INTELLIGENCE FORTHEZX81? YES! SYNCZX is an artificial intelligence program with natural language capabili- ties for the ZX81 with 16K RAM, avail- able from Frog Software. SYNCZX will talk to you in ENGLISH/ NO MENUS. You can use SYNCZX to balance your checkbook or you can re- program SYNCZX to do anything you would like. However you do not need programming skills to use SYNCZX as is. Even a child can use SYNCZX be- cause it is easy to read and understand, talking to you in simple English. SYNCZX even remembers the people who use it! 16K cassette with manual only $6.95 plus $1.50 postage & han- dling. ALSOAVAII ABLE PERSONAL COMPUTING PACKAGE 7 programs. Graphs (1K), Appoint- ment book (16K), Checkbook (16K) and Three Games ( 1 K), etc ... All 7 for only $1 .95 plus .70c postage & handling. Send to: Frog Software Box 95 Glenmont, New York 12077 (518)465-6552 September/October 1982 61 BOLEX: Beginner's Ohm's Law EXer ClSeS Ray Stadia .Figure 1. Ohm's Law Variations.. Ohm's Law George Simon Ohm (1787-1854) was a German schoolmaster who studied the electric circuit and determined the relationship of voltage, the electromotive force (E); current, the intensity of elec- tron flow (I); and resistance, the oppo- sition to electron flow (R). The results of his experiments were expressed in the equation E=IR which can also be expres- sed as I=E/R and R=E/I. To those outside the field of electricity, this equation, now called Ohm's law, may not seem very impressive, but it plays a very important role in the design and creation of such everyday wonders as electric lights, telephones, toasters, TVs, car starters, refrigerators, and computers. Before Ohm's work, unknown values of voltage, current, or resistance had been difficult, even impossible, to find experi- mentally. However, these unknown cir- cuit values can now be found quickly and accurately by mathmatical computation from Ohm's equation. Despite this con- tribution of great importance to electrical science, Ohm lost his teaching job. In addition to voltage, current, and resistance the electric circuit includes a fourth element: wattage, the measure of power consumption. Wattage is found by another equation: P=IE, in which P stands for watts. Thus, watts equal current times voltage. Notice that the power equation and Ohm's equations all have the terms I and E in common. Knowing how mathematics handles equations with common terms, we can see the expanded versions in Figure 1. BOLEX BOLEX is a program that solves these equations two at a time. Enter the pro- Ray Stadta, 120 Calle Cuervo, San Clemen te, CA 92672. Translated to 8K ROM by James Grosjean, I Amps = E R P E 4 E Volts = IR yPR I R Ohms = E I E 2 P P I 2 P Watts = IE I 2 R E 2 R gram into your computer, hit RUN and NEWLINE. Four prompts will appear on your screen: amps, volts, ohms, and watts. Type in a value for one, hit NEWLINE. Continue until the values have been entered. With two values you will be able to find the other two. Try the following sample runs: 1) An appliance circuit has a current rating of 9 amps with 120 volts applied. What is the value of resistance in ohms and the power consumed in watts? Input: amps: 9; volts: 120; ohms: 0; watts: 0. The program finds the ohms and watts by solving the equations: R=E/I and P=IE. 2) How much current is drawn and how many watts are consumed by a 120 volt heating unit with 14 ohms resistance? Input: amps: 0; volts: 120; ohms: 14; watts: 0. The amps and watts are found by solving: I=E/R and P=IE or P=E*E/R where E is small enough not to cause an arithmetic overflow. 3) How much amperage and resistance is in the circuit of an appliance that uses 1625 watts plugged into 120 volts? Input: amps: 0; volts: 120; ohms:0; watts: 1625. The program solves: I=P/E and R=E*E/P. 4) A high-voltage circuit draws 5 amps with a known resistance of 450 ohms. Find the watts and volts. Input: amps: 5; volts: 0; ohms: 450; watts: 0. The program solves: E=IR and P=IE. RMPS (I) 97841 ^OLTS CO 0.13935 OHMS URTTS #" "OHMS ^>##*' "WATTS (P)#" 40 PRINT SO INPUT E 60 PRINT E ■ RIN1 80 INPUT R 90 PP1N1 R I PPINT 110 INPUT P NT P PKIN1 140 GO TO A&SC150* ( I+E=0>+260*< l+R-'J) 4-3501 ( I+-P-0) +450* (E+R=0>+4 B0*(E-MP»0>+510* (R+P-O) > 150 LET H=1B2 1 60 L L I 170 LET E=(L+-H>/2 18" I #R)/E 190 IF k>E THEN GO T U 200 IF H-L<2 THEN GO TO 240 IF K "; 80 INPUT R 90 PRINT R 100 PRINT "URTTS lP> '*; 110 INPUT P 120 PRINT P 130 PRINT 14.0 GOTO (150* (I + E=0> +150* (I + R = 0J 4-210* (X*P=0> +24.0* (E+R=0J +270* t E+P=0> +300* (R+P=01 ) 150 LET E =SOR (P*R> 150 LET I =P/E 170 GOTO 320 150 LET I =f>/e; 190 LET R =E*e./p 200 GOTO 320 210 LET I =E>*R 220 LET P = I*E 230 GOTO 320 240 LET E =P/I 250 LET R *&SX 260 GOTO 320 270 LET E = I*R 260 LET P = I*E 290 GOTO 320 300 LET R mBSX 310 LET P = I*E 320 PRINT I; " RMPS" 330 PRINT E; " OOLTS" 34.0 PRINT R; - OHMS" 350 PRINT P; " URTTS" SYNC Magazine SOFTWARE DR. FLOYD Psychoanalysis by computer? - well, not quite but Dr. Floyd will carry on a conversation with you using psychoanalytic techniques giving the appearance of artificial intelligence. Requires 16K RAM. $10.95 GRAPHICS PAC I An introduction to Sinclair graphics - includes a 1K Line Doodler, a 16K Super Line Doodler, several random drawing programs and a Screen For- matter. Kids will love all of them. The screen formatter will satisfy serious programmers. Requires 16K for full use but simpler sections will run with 1 or2K. $10.95 WORD PLAY Fun with words - 2 jargon generating programs for grown ups, 2 story writers for children and a bonus secret message program. Requires 16K. $9.95 All software is on high quality cassettes and is replacement guaranteed. ZX81 - TS1000 >45 95 HARDWARE SIN16 16K RAM This RAM plug-in allows the user to run virtually all programs written for the ZX81 or TS1000. Completely assembled & tested s 135 95 SUPER SIN64 64K RAM TO ORDER: Send Check or MO For the total + $4.00 S & H Calif, residents add 6% tax. or PHONE 805/482-3604 This is the maximum directly address- able RAM that your ZX81 or TS1000 can use - Memory is used as follows: 0-8K Sinclair operating ROM. 8-16K switches in or out of use. Used for assembly language routines, memory mapped peripherals. Contents are safe from NEW and cassette (disc) loads thus allowing progrom-to-program communications. 16-32K BASIC and assembly language user program area. 32-64K large data arrays & BASIC variables. ^^3^^ VISA All hardware is completely compatable with Sinclair add-on products. Both RAMS use the mose reliable gold plated, bifurcated contact connector on the market. For credit card orders, include all info on card. PROPOS TCCHNOLOGV. 10 day return privilege on all hardware-90 day parts and labor warranty-inexpensive extended service contract is available- WE SERVICE WHAT WE SELL. 350 N. Lantana Ave., Suite 821 • Camarillo, CA 93010 ZX-FORTH Now you can have the SPEED and POWER of com- puters costing hundreds or even thousands of dollars more inside your ZX81. FORTH is now available on cassette for the 1 6K ZX81 . EASIER to learn than BASIC and the most powerful language available for the ZX81 10 TO 20 times FASTER than BASIC and typically uses less than HALF the amount of RAM space needed by an average BASIC program. Includes extentions for speedy graphics handling, as well as basic data han- dling functions. Sample programs written in FORTH in- cluded at no extra charge are: Scratch pad, a simple word processor, Breakforth and Arcade-type game. Also included is a complete bibliography and informa- tion about fig-FORTH, the international FORTH users group. Find out why FORTH is gaining worldwide support as the state of the software art and have fun learning about computers the fast and easy way. STRATOS CORPORATION 1451 N.UNION STREET MIDDLETOWN, PA 17057 ZX-FORTH 16K CASSETTE $34.95 Add $2.00 shipping and handling. Add $7.00 shipping and handling for foreign orders. LTEXT AND ZTEXT ZX81 WORD PROCESSORS lower case characters on the ZX printer!! $14.95 Plus $2.00 Airmail Postage No long. nips and ihe like With these programs your ichine ZTEXT (upper case characters only) and LTEXT (upper and lower case characters) are word processors which incorporate a text editor and a formatter printer The text editor allows you to type test in il The formatter printer takes the text and sends it to be screen or ZX printer, justifying it and formatting a< mands embedded in the text Included in the iseful operations as string search, string ret merge facility enabling a sketel ' 10 be filled with variable information LTEXT caters foi not a misprint By utilising the high resolution graphics feature of the ZX printer Graham Asher has built a complete set of ise characters These prograi ' "led manual Send S2 00 (redeemable against first order) for full catalogue and FREE listing Please state ZX81 on All pn> . A i and P&P available from Oasis Software. 20 Canterbury Close. Worle. Weston Super Mare, England Dealer inquiries invited ACCfcbb ORDERS TAKEN BY PHONE 24 HOURS A DAY Repeat Key Option George R. Ingle Ed.- A WORD OF CAUTION: Any hardware project for your computer must be approached with extreme caution. SYNC cannot be responsible for any problem that may arise from attempting hardware projects. Obviously, any dam- age to your computer can be costly in time and money. A repeat key option is relatively simple to build and install. In addition to IC sockets, wire, and a suitable mounting board, one of each of the following parts is required: 555 timer IC. 74LS244 octal non-inverting tri-state bus driver. IOOuF miniature electrolytic capacitor rated 15v or greater. IK ohm resistor rated 1/4 watt. 5 or 1 OK miniature POT. SPDT miniature switch. The steps in construction are as fol- lows: 1) Connect all components. Lead lengths and component placement are not critical. Good soldering practices should be followed, as usual. See Figure 1. Figure 1 : Typical Diode Anode . A &- Cathode C Typical Diode DlC=Diode 1 Cathode DlA = Diode 1 Anode etc. for all connections 2) Carefully de-solder and remove the eight ln4148 diodes in series with the keyboard contacts. These diodes are soldered to the computer printed circuit board in plated-through holes. You must be very careful not to damage the signal line connects to these holes. On the Sinclair these diodes are numbered D3 through D10; on the MicroAce, Dl through D8. 3) Carefully solder the wires to the diode holes as shown. Make sure that solder flows through the holes and makes a good connection. 4) Connect the chip grounds and 5v pins to a place on the circuit board. Just about any connection supplying the nee- George R. Ingle, 24593 1/2 Monterey Ave., San Bernadino, CA 92410. essary voltages can be used except the 5v input to the VHF/UHF modulator. This would result in unwanted "noise" created by the 555 timer being sent to the TV and causing distortion in the display. 5) Install and connect the switch. This switch allows you to select the repeat function or to return the keyboard to its normal operating state. The logic low KBD signal can be tapped at pin 1 on IC 10 for the Sinclair or pin 1 on IC 11 for the MicroAce. This keyboard signal, when connected to the 74LS244 allows normal operation of the keyboard. See Figure 2. 6) Set the repeat rate or frequency by adjusting the 5 or 10K POT. The repeat rate selected will remain stable, but keep in mind that the repeat rate will be slower on a ZX81 or MicroAce equipped with the video upgrade operated in the slow mode since these machines insert addi- tional delays generated by the retiming character display frequency. Too high a repeat rate will make you "outrun" the keyboard scan frequency used by the Z80 during an IORQ and RD. This will not be a problem since the rate at which this occurs is very difficult to follow with your eyes! 5 . Figure 2: Schematic for Keyboard Repeater. ^■\100uF A8' A9 A10 All A12 AI3 AI4' A1S D1C D2C DX EMC DVT D6C D7C DKC X II 13 15 17 ^ IN Yl6 Yl4 Yl2 T9 Y- Ys Pin20=+5v Pin 10=GND 3k I DlA D2A D3A D4A DSA D6A D7A DKA I 66 SYNC Magazine "Touch-A-Matic ", Power At Your Finger Tips! $9.95 KOPAK'S TOUCH-A-MATIC™ gives you the power to type more accurately and much faster. It requires no wires, no soldering. Comes with complete instructions. It's as easy as removing adhesive backing and pressing into position. Positioning is easy. Once in position, you are ready for touch- typing with ease. Our unique vinyl-key-hold creation will guide your fingers to the correct keys. Finally, touch-typing now possible with your Sinclair* or Micro- Ace*. This remarkable product, as well as other KOPAK items, are now available. Call now to order through MC/Visa or send check/M.O. to Kopak Creations, Inc. TM Trademark of KOPAK Creations, Inc. Sinclair* is a trademark of Sinclair* Research LTD. MicroAce* is a trademark of MicroAce* KOPAK CREATIONS, INC. (212)757 8698 Master Charge & Visa Accepted $1.50 Handling Charge Dept. SY1 448 West 55th Street, New York, NY 10019 (212> 7578698 8K ROM IK RAM Degrees, Grads, and Radians Alvin Lam There are three methods of measuring angles: degrees, grads, and radians. How- ever, the ZX81 with all its new trigono- metric functions can only measure angles in radians. You can convert a measure- ment by any of the three methods to either of the remaining methods with the few short programs given in the listings below. You may want to add a REM statement to identify each listing for use in a program. Type in the program you need. Hit RUN and ENTER. One prompt will appear on the screen, e.g., in Listing 1, RADIANS=. Type in the number of radians you want converted to degrees and press ENTER. The answer will appear. Alvin Lam, 690 Sunset Pkwy., Novate CA 94947, Listing 1 : Radians to Degrees. _ 10 PRINT "FmDIRNS= " ; 20 INPUT R 3® PRIHT R 4-0 LET D=R*I80/PI 50 PRINT "DEGREE5=' : ;D 60 STOP Listing 2: Degrees to Radians.. . Listing 4: Grads to Radians. 10 20 30 4-0 50 60 PRINT "GRfl05 = ".; INPUT G PRINT G LET R»G/€>3 . 6fc, 197*7 PRINT "RfiDIRNS = ".; R STOP Listing 5: Degrees to Grads. _ 10 PRINT "DEGRE£5=" 30 INPUT D 30 PRINT D 4-0 LET R=PIiD/160 50 PRINT "RRDIRN5 = kt 60 STOP 10 PRINT "DEGREES^".; S0 INPUT D 30 PRINT D 4-0 LET G=0^-. S 50 PRINT s 'GRPtr>S = " ;G 60 STOP Listing 3: Radians to Grads. 10 PRINT ,! RHDIfiN5 = ": 20 INPUT R 30 PRINT R 4.0 LET G=63.661977*R 50 PRINT "GRfiD5=";G 60 STOP 10 PRIHT "G.RRDS = ";- 20 INPUT G- 30 PR INT G 4-© LET D: =G* ,Q 50 PRINT "DEGREE5=' " ;D 60 STOP COSMONICS ZX81 HARDWARE/SOFTWARE EXTENTIONS CS 17 Cassette Read/Write Utilities. Allows the user to selectively read & write strings and arrays to a cassette, which can be used by the same program or a different pro- gram. CS 1 7 cassette $20.00 CS 21 Software for TTL Serial Output Port. Provides cor- rect RS232 timing; provides Sinclair character set transla- tion to ASCII. CS 21 cassette $10.00 *CH 21 Complete Plans for 2 IC Serial Output Port for ZX81 . CH 21 plans $10.00 *CH 21 K 2 IC Serial Ouput Port Kit for 2X81 (complete plans and parts) CH21K kit $15.00 CS 22 Software for Serial Input. Provides RS232 input tim- ing and provides ASCII to Sinclair character translation. CS 22 .cassette $10.00 *CH 22 Complete Plans for ZX81 Serial Imput Port. CH 22 plans $ 5.00 CH 24 Complete Plans for RS232<^>TTL Level Converter. CH 24 plans $10.00 CH 46 46 pin edge connector for ZX81. CH 46 . . . .... connector . $ 8.00 All cassette software listed here requires a minimum of 2K RAM *Note: Any modification made on the ZX81 may invalidate the Sinclair warranty. Please add $1.50 postage and handling with each order. California residents add 6% sales tax. COSMONICS, Box 10358, San Jose, CA. 95157 PRACTICAL ZX-81® SOFTWARE ZX-81" Not Just For Games Anymore! ZX-PANDING, LTD., an American company, uses the tremendous ZX-81 1 * data handling capabilities to make our daily tasks easier. Programs are on cassette, thoroughly tested, with easy-to-read printed instructions, written in BASIC to allow tailoring to your special needs. _ 1 . YOUR SPECIAL DAY— 1 K--Good example of using succes- sive equations to answer a practical question. Enter any date in history, and ZX-81 ^ will tell you the day of the week on which it occurred. Useful in many fields and a great ZX-81^ demonstration ONLY $3.75* 2. CLOCKS AND TIMERS— 1K— A digital clock (standard or _ military time), a count-up timer (for telephone calls), and a count-down timer (useful in cooking). Another great ZX-81^ demonstration .ONLY $3.75* 3. ANYP0INT PLOTTER— 1K— Crunches any data to allow graphing of any positive data points: stock prices, temperature, experi- mental data, etc. . . . ONLY $3.75* 4 CHECKBOOK, INCOME TAX AND BUDGET ORGANIZER— 16K A powerful yet easy to use finance program — 10 jobs in menu driven format. Checks and deposits are totaled and itemized under desired categories for budget planning and income tax preparation. Makes checkbook balancing easy. Ninety transactions manipulated at one time with 16K . .ONLY $13.75* ZX-PANDING, LTD. P.O. BOX 25 NEWTON, NC 28658 Free catalog with self addressed stamped envelope. •ALL orders please add $1 25 to total order to cover POSTAGE AND HANDLING (Foreign orders add $2.00 to cover air costs. Your payment must be in a US. dollar draft payable to U.S. bank.) Rounding Off with Conditional Tests James E. Stauffer We have all learned in plane geometry classes the Pythagorean theorem: a squared plus b squared equals c squared. Thus, if we know two sides of a right triangle, we can easily calculate the third. Or can we? My son pointed out a Basic program for finding "Pythagorean triples" in his geometry textbook (Jurgensen, Donnelly, Maier, and Rising. Geometry. Boston: Houghton Mifflin Co., 1978). These are the solutions to a right triangle when all three sides are positive integers. I trans- lated the program into ZX81 Basic as follows: 10 FOR A=l TO 20 20 FOR B=A TO 20 30 LET C=SQR(A*A+B*B) 40 IF C <> INT C THEN GOTO 60 50 PRINT A;TAB 5;B;TAB 10;C 60 NEXT B 70 NEXT A James E. Stauffer, 6076 Chinaberry Dr., Columbus, OH 43213. Then we ran the problem, and the display appeared as follows: 8 15 17 0/70 This result was a surprise. What had happened to the famous 3, 4, 5 triangle, let alone all the other solutions we were sure were there? It was obvious from the display that the program was working and that it had exhausted all possible values of A up to 20, stopping at line 70. The problem had to be in the con- ditional test in line 40 which says in effect, "PRINT only solutions in which C is an integer." Some of the obvious solutions must be failing the test. We decided to see what was happening by going to the immediate mode, i.e., entering text without line numbers, and typed: LET A=3 LET B=4 LETC=SQR(A*A+B*B) PRINT C The screen display showed 5, which is an integer, or is it? Knowing that some 8KROM IK RAM algorithms, such as SQR, produce round- off errors, we next tried: PRINT C-INT C The number 1.8626452E-9 appeared. Here was the problem. A tiny error, outside the display range of the ZX81 had caused many solutions to fail the conditional test of line 40, which demands that INT C be exactly equal to C. The solution then was to rewrite line 40 to permit small errors in the SQR solution forC: 40 IF C-INT C> 0.000001 THEN GOTO 60 When we ran the problem with this change, we got the following results: 3 4 5 5 12 13 6 8 10 8 15 17 9 12 15 12 16 20 15 20 25 0/70 These are the proper solutions for all Pythagorean triples for sides A and B less than or equal to 20. ZX81 users must be prepared to accept slight imperfections when the computer is dealing with non-arithmetic functions. The algorithms used are powerful, but some round-off errors may be present. S UNFORGETTABLE MEMORIES NONVOLATILE MEMORY AND PORTS • 4 -2K sockets for expansion RAM and/or popular 2716 EPROMS • 6 - 8 bit I/O ports • Sinclair memory module interface This I/O unit can utilize combina- tion of EPROM, static RAM, or nonvolatile RAMs. Put often-used USR routines in EPROM or NOVRAM for easy access, or use 2K static RAMs for storage not affected by tape commands. Our ports are easily accessed using BASIC PEEK and POKE, or at very high speeds with USR routines. The Wisconsinc I/O unit has 24 input and 24 output lines. Your memory module will plug directly onto our I/O unit. Address lines are buffered for reliable memory operation. Power your ZX-81, the I/O unit, and peripherals like our EPROM programmer with our optional power supply. I/O UNIT Assembled and tested $99 Kit with complete instructions . . $79 Optional power supply $19 32K MEMORY WITH 4 I/O PORTS • Large memory capacity greatly enhances ZX-81 computing power • 2 input and 2 output ports • Use with our EPROM programmer This memory is designed for economy and flexibility, complete with aluminum enclosure and power supply. We also feature our profes- sional p.c. board with connector for the budget minded. Either way you get complete instructions for the 32K with ports. Our 32K memory provides you with up to 16K for BASIC program and at least 16K for variable storage. This allows the use of iarge arrays, which is especially useful to scientific students. 32K MEMORY WITH PORTS Complete kit with instructions . $166 16K version, kit $131 Bare board with connector . . $ 40 LOW COST EPROM PROGRAMMER • Programs popular 2716 EPROM • EPROMs compatible with our I/O unit • Save USR code in nonvolatile EPROM • Requires 3-port interlace to ZX-81 Programmer hardware with soft- ware will program or copy an EPROM. Use EPROMs in our I/O unit and have your own USR routines at your fingertips. EPROM PROGRAMMER Assembled and tested $79 TERMS: Wisconsin residents add sales tax. Fiedse add $4.95 for shipping and handling. Check or Money Order only. Allow 4-6 weeks for delivery. Wisconsinc Electronics PO Box 332 Milton, Wl 53563 September/October 1982 69 8k ROM Ik RAM Block Transfers: Horizontal Scrolling On your 1 K ZX8 1 John Scher A programming technique called block transfers of memory adds new possibilities for your programming and for taking advantage of your computer's capabilities. Although the technique involves the use of machine language, this article assumes only that you are familiar with the Sinclair manual ZX81 BASIC Programming and that you are willing to work with hexa- decimal. Dr. Ian Logan's article, "An Introduction to Machine Language" {SYNC 1 :6) is helpful, but not essential. For some readers learning may be its own reward. For those who want a more concrete incentive, this article will show how to modify Douglass D. Sharp's LSCROLL routine (SYNC 2:2) for a IK machine. Using this routine, you will be able to launch a fleet of jets, in formation, across your TV screen . . . that is, after a little homework. What is a Block Transfer? We must begin by defining a block of memory. This is the information held in a set of sequential addresses in the memory of the computer. The contents of a REM statement, for example, constitute such a block. A block transfer of this information would write the contents of the block into a different area of memory. That is, the sequence is reproduced at a new starting address. Furthermore, the original sequence is not disturbed unless the "source "and "destination "areas overlap. RAMTOP To use this programming technique, we must first understand the systems variable called RAMTOP. Reviewing the information on RAMTOP in ZX81 Basic Programming, Chapter 26, would be help- ful at this point. The discussion below draws on this chapter and supplements it. John Scher, 222A Hamilton St., Cambridge, MA 02139. When you turn on the ZX81, it tests to see how much memory it has to work with and then stores the address of the first non-existent byte for future ref- erence. This address is called RAMTOP. It is stored at addresses 16388 and 16389. For example, if you have IK RAM, type: PRINT PEEK 16388+256*PEEK 16389 and ENTER. This will tell you that the address of the first non-existent byte is 17408. This is RAMTOP. You can change RAMTOP by POKEing the appropriate values into addresses 16388 and 16389 then typing NEW and ENTER. For example, suppose that you want to establish RAMTOP at 17388. You would type POKE 16388,236 and ENTER; then POKE 16389,67 and ENTER, and then NEW and ENTER. These values produce the new RAMTOP address by the following calculation: 236+256*67=17388 This POKEing will fool the machine into thinking that there is no usable memory above RAMTOP (17388). As a result nothing above that address will be disturbed by the Basic system. The area above RAMTOP is also undis- turbed by LOADing a new program into the machine. The usefulness of this area cannot be overemphasized because it gives the user a place to store machine code, Basic data arrays, and other mem- ory blocks. These are then available for use in multiple Basic programs without having to type in the machine code or data each time you want to use it. The only disadvantage of this area is that it is not saved by SAVE. This is why block transfers are so useful. They allow the transfer of information from a SA VE- able area of memory to one that is undis- turbed during program LOADing. A Basic Program for a Block Transfer Figure 1 shows a block transfer pro- gram in Basic. This program locates the bytes, in this case X's, in the REM state- ment and transfers them to a new starting address. The address of the first X in the REM statement is 16514. Before using such a program to place machine code bytes above RAMTOP, you must first reserve space above RAMTOP as we have already discussed. The bytes in Figure 1 could just as easily be in an array or another Basic variable. Either of these would be sim- ilarly SAVEable, although locating the starting address for a block transfer would be a bit more difficult. Figure 1. A Basic Program for Block Transfer. 1 REM XXXXXXXXXX 10 FOR N=0 TO 9 20 POKE 17398+N.PEEK (16514+N) 30 NEXT N The LDIR Instruction Given that much of the work of a computer is moving things from one address to another, it is not surprising that the Z80(A) microprocessor has a command that can accomplish a block transfer much more quickly and efficent- ly than a Basic program like that in Figure 1. This is the "Repeating Block Load With Increment" instruction, LDIR. The LDIR instruction makes use of three register pairs: BC, DE, and HL. Initially, the BC register pair must hold the number of bytes that you want to transfer, just like the FOR-NEXT loop in Figure 1 . The DE pair holds the first address in the "destin- ation" block of memory, and the HL pair holds the first address in the "source" block of memory. The LDIR instruction 70 SYNC Magazine transfers the contents of the address held in the HL pair to the address held in the DE pair. Then it increments HL and DE (i.e., adds 1) and decrements BC (i.e., subtracts 1). It then compares the BC pair to zero, and, if BC is not equal to zero, the instruction is repeated, other- wise the next instruction is executed. Although we will use LDIR in the sample programs in this article, you should know that LDIR has a cousin, LDDR, which is similar except that it decrements all three registers. You might think about which of these two you would use to transfer overlapping memory blocks. An Overview of the Process At this point let me summarize what we are going to do. We will enter a machine code block transfer program along with a sample machine code routine to be transferred into the space above RAMTOP. Then we will transfer this block of memory to a SAVEable REM statement. At this point, a few mod- ifications will be made, and then we will try out LSCROLL with a sample Basic program. There are slightly easier ways to achieve the same end result, but this sequence will teach you the most. A Machine Language Block Transfer The first step in entering the machine language block transfer program is to reserve 184 bytes above RAMTOP by typing POKE 16388,72 and ENTER, then POKE 16389,67, and ENTER, and then NEW and ENTER. Now that you have reserved the necessary space above RAM- TOP, enter the hex loading program shown in Figure 2 (from Booth, "The Game of Life Revisited," SYNC 2:1, p. 20). When you RUN this program, the screen will prompt you for a byte in hexadecimal. Refer now to Figure 3, which lists the block transfer machine code. Note that the first nine bytes (con- tained in addresses 17224-17232) set up the BC, DE, and HL register pairs (LD stands for load) as discussed above. The next two bytes perform the transfer, and the last returns the computer to Basic. Note that all addresses within an LD instruction, for example, 4082h = 16514d, are entered lower-order-byte first, higher- order-byte second, in the same manner used to change RAMTOP. Remember that a in a hexadecimal listing such as in Figure 3, column 2, is always a zero and never the letter O. Now that the screen is prompting you for an entry, enter the bytes in Figure 3, column 2 (i.e., type 01 and ENTER, then B8 and ENTER, etc.). Then go directly to Figure 4 without typing RUN and con- tinue by entering the LSCROLL sequence. The parentheses and asterisks will be explained later. For now just September/October 1982 Figure 2. Hex Loading Program. 200 LET V=-l 210 LET V=V+1 220 IF INT (V/50)*50=V THEN GLS 230 IF INT (V/10)*10=V THEN PRI NT 2^0 INPUT H$ 250 IF H$= ,,M THEN GOTO 2^0 260 PRINT H$;"# M 270 IF H$="END M THEN STOP 280 IF H$=V" THEN GOTO 310 290 POKE 1722^+V t l6*C0DE (H$)+C ODE (H$<2))-476 300 GOTO 210 310 LET V=V-1 320 GOTO 240 Figure 3. The Block Transfer Machine Code. Decimal Hex Instructions Address Code 17224 01 LD BC,#of bytes 17225 B8 00B8h=l84d 17226 00 17227 11 LD DE, destination 17228 82 4082h=l65l4d 17229 40 17230 21 LD HL, source 17231 48 4348h=17224d 17232 43 17233 ED LDIR (transfer) 17234 B0 17235 C9 RET (return) Fl sure 4. The LSCROLL Seauence. 17236-17407 ENTER the LSCROLL sequence: 3A(FE .43)FE.l6.DA(6l .43)3E.00.32(FE.43)3A(FF.43)D6.0 0.CA(71.43)FE.15.D2(71.43)C3(76. 43 ) 3E . 1 6 . 3 2 ( FF . 43 ) F5 . 3A ( FF . 43 ) 47 .F1.3A(FE.4-3)80.PE.l6.DA(95.43)2 6 . . 2E . 1 6 . 3 A ( FE . 43 ) 4F . 6 . 6 .ED . 42 . 7D . 32 ( FF . 43 ) ED . 5B . 0C . 40 . 0E . FF .F5.3A(FE.43)6F.F1.26.00.06.00.1 A.FE.76,CA(AF.43)13.C3(A5.43)0C. A7. E5. ED .42 . El .CA(BC. 43)13.C3(A5 .43)06.00.F5.3A(FF.43)4F.F1.C5.D 5.E1.23.7E.FE.76.C2(C7.43)E5.A7. ED.52.2B.7D.4D.D6.00.E1 .C2(E0.43 )E5.D1.C3(F5.43)3D.C2(E8.43)13.C 3 ( Fl . 43 ) 06 . 00 . OB . 1 3 . D5 .El . 23 .ED . B0.3E.00tl2.13.C1.0B.79.D6.00.C2 (C4.43)C9.O0fO0f Figure * ». Changes for Transfers from REM to above RAMTOP. Decimal Hex Code Instructions Address Code Changes 16514 01 16515 B8-« ►AC= 172d .change #bytes I6516 00-H ► 00 , no change 16517 11 16518 82^. ► 54= 84d change dest . 16519 40-i ►43= 67d ,4354h- 17236d 16520 21 16521 48-« ►8E= l42d change source 16522 43-# ■ 64d 4o8Eh= l6526d 16523 ED 16524 B0 16525 C9 ignore them (i.e., type 3A and ENTER, then FE and ENTER, then 43 and ENTER, etc.). If you make a mistake while entering this machine code, note that line 280 in Figure 2 gives you a backspace key, V". When you are done entering the machine code in Figure 4, type END and ENTER, and the loading program will STOP. At this point you should check to be sure that you did not leave out a byte or two accidently by typing PRINT PEEK 17405 and ENTER. The number 201 should appear at the top of your screen (201d = C9h). Congrat- ulations if you have come this far without leaving anything out! Next, SAVE the hex loading program for future use. Then type NEW and ENTER to clear out the memory for the REM statement that we will use as the destination block of memory. Put the computer into FAST mode to enter the REM statement, otherwise it will take forever. Type 1 REM and then 184 X's, as in Figure 1, and ENTER. You can change back to SLOW mode now. Transferring LSCROLL Now you are ready for the block trans- fer. Type RAND USR 17224 and ENTER. The transfer will occur so fast that you will think that you made a mistake. Type ENTER again and you will see the first few bytes of machine code in the REM statement. If this does not occur you had better PEEK a few addresses between 17224 and 17235 to look for mistakes. Before you SAVE the REM statement, a few changes must be made so that in the future, when you LOAD the program, the block transfer will work in the other direction, that is, it will transfer LSCROLL from the REM statement to above RAMTOP. Also, the first twelve bytes need not be transferred because they make up the block transfer routine, not the LSCROLL routine. Figure 5 shows the changes you must make. Column 1 lists the addresses that the block transfer machine code routine occupies in the REM statement, and column 2 is identical to column 2 in Figure 3 for comparison. Column 3 gives the decimal values which must be POKEd in. Type POKE 16515,172 and ENTER, then POKE 16518,84 and ENTER, etc. until you have POKEd all five changes in. Now SAVE "LSCROLL". In the future, when you want to use LSCROLL, reserve 172 bytes above RAMTOP (POKE 16388,84; POKE 16389,67; NEW), then LOAD "LSCROLL" and transfer it to the space above RAMTOP by typing RAND 16514. In fact, you should do this now to reclaim the twelve bytes of memory above RAM- TOP that were needed before to make the block transfer to the REM statement. You will need all the memory available for the sample Basic program in Figure 6. 71 Using LSCROLL from above RAMTOP Once you have LSCROLL above RAM- TOP, type NEW and ENTER to get rid of the REM statement. Now you have enough space to enter the Rockets pro- gram in Figure 6. Note that the Rockets program POKES three addresses in the LSCROLL routine, 17394, 17406, and 17407. These addresses correspond to the Figure 6. Rockets Program Listing. 1 REM ROCKETS * POKE 17394,14 5 FOR H=6 TO 14 10 PRINT RT H,3l;"B' 15 NEXT H 17 FOR M=0 TO 4 20 POKE 17406,10-M 30 POKE 17407,1+2*M 35 FOR N=© TO 32 40 RflND USR 1723© 45 NEXT N 50 NEXT M 60 CL5 70 GOTO 5 bytes in Figure 4 that are followed by asterisks. The function of these addresses is as follows: 17394 specifies the code for the char- acter which will occupy the new spaces created by LSCROLLing. 17406 specifies the line number at which to begin LSCROLLing; POKE in a number from to 21; see ZX81 BASIC Programming, p. 89. 17404 specifies the number of lines to be LSCROLLed, including the first one; POKE in a number from 1 to 22. Add 1024 to these addresses if you have 2K RAM (see below). Rockets calls the LSCROLL routine with the line 80 RAND USR 17236 since the starting address of the LSCROLL routine is 17236. Now comes the moment of truth. RUN Rockets. If you have come this far without making a mistake, you will see a line of jets form on the right side of the screen and take off across the screen in for- mation, leaving their contrails behind. For More Than IK RAM Those with more than IK RAM may want to locate LSCROLL at a higher starting address. For instance, if you have added IK for a total of 2K RAM, you have an additional 1024 bytes. Therefore you could move RAMTOP to 18260 (17236 + 1024) for the final run which only requires 172 bytes. Do not forget that the hex loading program requires 184 bytes above RAMTOP. You will have to make these changes to move RAM- TOP. First, add 1024 to the following addres- ses in the figures: Figure 2: Line 290. Figure 3: all addresses in column 1. Figure 6: Rockets Program: all addres- ses. Next you must change some of the machine code. Figure 3, column 2: change the 9th byte from 43 to 47. Figure 5, column 3: 43 = 67d to 47 = 7 Id. Note that we have been adding 4 to the higher-order-byte of a series of addresses because 1024/256 = 4. Figure 4: The parentheses contain addresses of information or routines within the LSCROLL program. For in- stance, the first parenthesis (FE.43) con- tains address 43FEh = 17406d. Add 4 to the higher-order-byte, 43, in all the paren- theses. Thus the first parenthesis should read (FE.47). The program is ready for use at the starting address, 18260. If you have more than 2K, make sure that you understand the changes sug- gested for 2K users, then give the changes best for your machine a try. One last word of caution: look over the article and write in the changes you will want to make in the addresses in the text, as well as the addresses referred to in the figures. As you can see, LSCROLL is a superb program in that it allows the user to chose exactly which part of the screen to scroll. You are now ready to try some of your own programs with the LSCROLL rou- tine. The program has many other virtues that are detailed by the author, and I give it the highest rating of any machine code program that I have seen in SYNC. S HE SAID YOU COULDN'T DO IT WE DID IT! REVOLUTION IN TEACHING PROGRAM TECHNIQUES APPRECIATE THE REAL VALUE OF YOUR COMPUTER READZX81 HORIZON (with tape) LEARN TO LINK COPY MOVE & MERGE NO PROGRAMMER SHOULD BE WITHOUT THIS BOOK CONTENTS. Detective, Billiards, Machine Code Programmer, Call Back Routine, File Text, Animated Cylist, Load & Save, We can accept no responsibility for any illegal use of these programs. From: NAME ADDRESS To: Uitgeverij Wolfkamp Postbus 70254 (1007KG) Amsterdam. Netherlands. Tel: Amsterdam 020-278931 Payment must be included with Order. Price $24.95 including Postage & Packing. Credit cards are accepted. 72 SYNC Magazine practical software FOR THE SINCLAIR ZX80/81 (8K/16K) 2 Unique computer programs on cassette ZX INVENTORY ZX DIRECTORY • STORAGE OF 200 ITEMS AND PRICES* SORTS FILES ALPHABETICALLY • PRINTING CAPABILITY (ZX81) • STORAGE OF 60 FILES ( 16K) • COMPREHENSIVE SEARCH • PRINTING CAPABILITY (ZX81 ) ROUTINES •COMPREHENSIVE SEARCH ROUTINES BOTH PROGRAMS EASILY MODIFIED TO STORE MORE FILES WITH LARGER RAM PACK. ONLY 19.95 EA. BOTH PROGRAMS FOR 34.95 SEND CHECK OR MONEY ORDER TO: SERVITRONICS P.O. BOX 2024, HARTFORD, CONN. 06145 FOR INFORMATION OR VISA OR MASTERCARD ORDERS CALL (203) 643-7900 SHIPPING U.S. $1 50 OUTSIDE US $3 00 PREMIUM CASSETTES COMPUTER GRADE 100% ERROR-FREE FULLY GUARANTEED r\J*B* pHlCl Add Sound to Your ZX81 ! Sounder circuit fits inside the ZX81. No cutting, soldering, or unsoldering. Circuit beeps when key inputs are accepted by the computer. Send $12.00 per unit plus $2.00 postage and handling (N.J. Residents add 5% Sales Tax) to KML Incorporated P.O. Box 1147 New Brunswick, N.J. 08903 The Micro-Trac™ Generation • High Frequency Response • Wide Dynamic Range • • Usedby Software Firms & Computer Hobbyists • • Choice ot School Districts Nationwide • LENGTH 12-PAK 24-PAK C05 $ .69 $ .59 C-10 $ .79 $ .69 C-20 $ .99 $ .89 C-30 $1.19 $1.09 C-60 $1.49 $1.39 C-90 $1.79 $1.69 •CASES $ .21 $ .20 'Cases recommended to protect sensitive cassettes. -UPS SHIPPING- B THEN LET E(D)=E( D)-l 520 IF F(D)C THEN LET F(D)=F( D)-l 540 LET M=2Q*E(D)+F(D) 550 IF A(M)-61 THEN POKE USR(1 6482)+M+E(D),147 560 IF A(M)=148 THEN PRINT "YO U HAVE BEEN DESTROYED" 570 IF A(M)=0 OR A(M)=148 THEN //GOTO 610 580 LET K=K+1 590 LET G=G+1 600 LET A=USR(16487) 610 IF A(M)=0 THEN LET A(M)=14 7 620 IF G=5 THEN GOTO 10 630 IF A(M)=148 THEN GOTO 660 640 NEXT D 650 GOTO 270 660 IF K>F THEN LET F=K 76 .Listing 4. _ Llsting 2. 2000 FOR X=16427 TO 16506 2001 INPUT A 2002 PRINT A, 2003 POKE X,A 2004 NEXT X _ Listing 3. - 2000 DIM E(21) 2001 DIM F(21) 2002 FOR D=l TO 21 2003 LET E(D)=0 2004 LET F(D)=0 2006 NEXT D -Listing 5. 42,12,64,35, 54,9,35,6,18 9,35,62,117, 234,6,20,54, 60,119,35,34 13,50,37,64, 42,12,64,6,0 37,40,02,52, 205,74,64,6,8,197, ,54,0,35,16,251,54, 60,119,35,193,16, 9,35,16,251,62,117, ,14,64,34,16,64,62, 201,42,12,64,35,201, ,14,220,9,126,254, 201,54,28,43,24,244 2000 DIM A(200) 2001 FOR B=0 TO 9 2002 FOR C=0 TO 19 2003 LET M=20*B+C 2004 LET A(M)=0 2006 IF B=0 OR B=9 OR C=0 R C=19 THEN LET A(M)=61 2008 NEXT C 2010 NEXT B SYNC Magazine Space Taxi Neil Dewhurst 8KR0M IK RAM You are the pilot of a space taxi in the year 2081. You have just picked up a fare who must catch the next ship to Zeta Chi LXXXI. Naturally, there is a big tip if you make it in one piece. You control your taxi by the 6 and 7 keys to avoid the buildings and the other traffic (which appears to be standing still because you are going so fast). If you crash before Neil Dewhurst, 2 Chesterbrook, Ribchester, Nr. Preston PR3 3XT, U.K. getting to the spaceport, the space odo- meter will show how many blocks you passed before the crash. Type in the program and then SAVE it before playing. After SAVEing, hit SLOW and ENTER. Your taxi is immediately underway. So be prepared to drive with the 6 and 7 keys. Graphics note: Line 60: inverse space. Line 150: inverse graphic on M. Line 1010: inverse space. Line 1030: inverse O. H THEN LET D=-l THEN LET D=l 3© 10 LET S = 2Q LET Y=2 3® LETT X=0 40 CL5 50 GOSUB 1080 60 PRINT RT Y,X; ' TO LET D=0 80 IF INKEY> S =■•7* , 90 IF XNKEY*="6" 100 LET 5=S+1 110 LET X=X+1 120 IF X«31 THEN GOTO 130 LET Y-Y+D 140 IF Y<1 THEN LET Y=l 150 PRINT RT Y.X;"JB" 160 PRINT RT Y.X+l; 170 IF PEEK (PEEK 1639© +256 *PEE K 16399) =128 THEN GOTO 60 180 PRINT S 190 INPUT J$ 200 RUN 1000 FOR «J*0 TO 31 J-29S EgS.J*£T°. 2 + INT (RND*4) 1010 PRINT RT I.*J;"»" 1015 NEXT I ' " 1020 NEXT U 1025 FOR 1-1 TO 15 1030 PRINT RT INT 1 a 9 a i m s t t h e 8 1 .■ R make it Play itself- Fast MC moves + optional RATED list of possible in o v es - " fl # 1 n v e r • s i o n ! £19.95 ea.+ 2.58 for the order,, Each ZETfl Program is shipped on a certified cassette tape with i Tif ormat i ve book 1 et ■ Cata 1 o9 s e ri t w i t h o r d e r o r w r i t e : 22 E T R 3 O R T W R R E PO BOX 3522,-GREEHVILLE, SC 29608 September/October 1982 PREMIUM DATA CASSETTES "MANUFACTURERS WHOLESALE PRICES* LENGTH 1 CASSETTE 100-PACK 500-PACK C-10 .59 .54 EA. .45 EA. C-20 .66 .61 .53 C-60 .89 .83 .79 C-90 $1.29 $1.21 $1.14 SOFTWARE PUBLISHERS —LET ACTS AUDIO PROVIDE YOU WITH ALL YOUR CASSETTE PRODUCTION REQUIREMENTS. CUSTOM SOFTWARE DUPLICATION — FOR SINCLAIR, TRS-80, APPLE, ATARI — GUAR- ANTEED TO LOAD. ACTS AUDIO ALSO SELLS HIGH-SPEED DUPLICATION EQUIPMENT MODIFIED FOR SOFTWARE DUPLICATION. ACTS AUDIO, INC. 70WESTILLIANAAVE., ORLANDO, FL. 32806 (305)423-0338 77 Book Review The Complete Sinclair ZX81 Basic Course FredBlechman The Complete Sinclair ZX81 Basic Course. Published by Beam Software, U.K. and Australia, 255 pages; softbound with two hole punched pages and two rings. In U.S. available from Softsync for $35; two program cassettes, $5. It has been said, 'It's not what some- thing costs that counts; it's what it's WORTH!' That certainly seems true in the case of The Complete Sinclair ZX81 Basic Course. You get 255 pages of 8-1/4* x 5-1/2' two-hole punched sheets held together by two rings in a fancy vinyl cover. Thirty-five dollars for this? It looks like a real ripoff ! Further inspection does not help. No author's name is given— just Beam Soft- ware, with publishers in England and Australia. Look in the back for an index, and you will not find one. Look in the front for a table of contents, and you find a single page headed 'INDEX.' First impressions, however, can be deceiving. The course begins with the assumption that you know practically nothing about Fred Blechman, 7217 Bernadine Ave., Canoga Park, CA 91307. computers or programming and holds your hand pretty tightly. If you are a beginner, you should go through each example with your ZX81 at your side. However, later chapters go into depth on some very valuable material for those intending to do significant programming ontheZX81. Chapter 1 starts with simple pro- gramming that a beginner really should be able to follow. This is unlike many so- called beginner's books. Chapter 2 explains simple flowcharting. Chapters 3 and 4 go into arithmetic operations and functions in depth with examples to explain the purpose of various functions while avoiding mathematical theory. Chapters 5 and 6 do a great job of explaining strings and string functions, including 'slicing 4 and substring handling. Chapter 7 covers editing with more infor- mation than the Sinclair manual. How- ever, it should have gone into more depth since efficient editing can be a real time- saver in programming. Chapters 8 and 9 explain loops and conditional statements well. Chapter 10 covers arrays, both simple and string. This is a subject of immense importance in the ZX81 since READ/DATA are not provided. ZX81 VIDEO INVERTER ADDS PROFES- SIONAL TOUCH. NO MORE EYE-STRAIN. DISPLAY SHARP WHITE CHARACTERS ON SOLID BLACK BACKGROUND TV SCREEN. A TOGGLE SWITCH LETS YOU CHOOSE BETWEEN NORMAL AND REVERSE. THE SMALL PRINTED CIRCUIT BOARD FITS INSIDE YOUR ZX81. ALL FULLY TESTED WITH CONCISE INSTRUCTIONS. MONEY BACK GUARANTEE. AVAILABLE AS KIT £5/ $10 READY BUILT C650/S 13 PRICES INCLUDE AIRMAIL. SEND C OR S CHECK. D. FRITSCH 6 STANTON ROAD THELWALL WARRINGTON CHESHIRE WA4 2HS UK SAVE YOUR MEMORY! AND YOUR MONEY! Battery backup unit for ZX80/81. This inexpensive unit lasts for 30 minutes on standard "D" cell bat- teries, protecting your valuable programs from glitches and power failures. Requires at least a 9 volt power supply (like Sinclair's) and 6 "D" cells (not included). Only $12.95 VOCAB BUILDER for ZX81 16K 60 words per cassette, for teens and adults $9.50 Send check or money order to: CSI COMPANY 132 E.PASCO LANE COCOA BEACH, FLA 32931 Chapters 11 through 15 cover subrou- tines, character codes and graphics, FAST and SLOW operation, screen for- matting, graphic layout, INKEYS, and PAUSE. Chapter 16 describes procedures for using a cassette recorder to store and retrieve programs, and Chapter 17 dis- cusses a programming method known as "top down programming." Chapter 18 has an excellent discussion of debugging programs along with expanded explana- tions of what the 15 ZX81 errors codes really mean. Chapters 19 through 22 get into the high ground of memory saving tech- niques, machine code programs, system variables, and advanced graphics. These chapters are definitely not for beginners, but greatly increase the value of this book for non-beginners. PEEK, POKE, and USR are illustrated with line renumber and memory-size machine language pro- grams cleverly hidden in REMark state- ments at the beginning of a Basic pro- gram. The various system pointers are discussed in sufficient detail to help you understand the very peculiar goings-on "under the hood," including the wild antics of the elastic display file of the IK ZX81. For those schooled in a different memory access, such as the TRS-80, this will be a real education! These chapters are just loaded with information either not available or well-hidden in the Sinclair Manual. The three appendices include the stan- dard 255 character set with all keywords, a priority listing for program operations, and several application programs that implement the techniques described in the book. The last 78 pages are a reference manual of all 64 ZX81 keywords, with a page or more of explanation devoted to each. For beginners and those not acquainted with some of the peculiarities of Sinclair 8K Basic, these pages are a treasure that can save a great deal of time and avoid much frustration, especially in translating programs from other Basics. This section alone may be worth the price of the book. Two cassettes, containing 18 programs from the book, are available separately. They loaded and ran perfectly. This saved a great deal of keyboard and debugging time. If you have any interest in learning to program your ZX81, especially if you are new in computing. 1 would recommend this course highly. If you are already a user, you probably do not need it. Instead you might buy ready-to-go programs and just enjoy! V 78 SYNC Magazine Software Review ZX81 Chess vs. ZX Chess II Martin Wren-Hilton sqnc SOFTWARE PROFILE Name of Package: ZX81 Chess. ZX Chess II. Type: Board Games System: Sinclair 8K ROM; 16K RAM Format: Cassette Summary: Two powerful chess programs Price: ZX81 Chess: £9.50. ZX Chess II: £15.00 Manufacturer: (ZX81 Chess) Micro-Gen 24 Agar Crescent Bracknell, Berkshire, U.K. (ZX Chess II) Artie Computing 396 James Reckitt Ave. Hull, North Humberside, U.K. Computer chess is becoming a very popular hobby for those who cannot find opponents on their level, and a large number of ''dedicated" machines are appearing with increasingly greater strengths. Another area of growing popu- larity is designing a chess program which is more powerful (i.e., a better player) than other chess programs. Two powerful chess programs are now available for the 16K ZX81: ZX81 CHESS by Micro-Gen and ZX CHESS II by Artie Computing. Both programs are supplied on cassette with detailed instructions. ZX8I CHESS has six levels of play; ZX CHESS //, seven. Both games set up a board and use the standard notation with rows 1 to 8 going up and A to F going left to right. ZX CHESS II also shows the letters of the columns and the numbers of the rows on the screen for quick reference when entering a move. The 24x24 board of ZX CHESS II is somewhat easier to use than the 16x16 board of ZX81 CHESS. The pieces are represented as follows: K King, = Queen, R = Rook, B = Bishop, N = Knight and I = Pawn. Black pieces are shown as black on white and white pieces as white on black. Martin Wren-Hilton, 4 Little Poulton Lane, Poulton-le-Fylde, Blackpool FY6 7ET, U.K. Entering your move is simple on both programs. For example, to move a piece from position E2 to E4 you would enter E2-E4 on ZX CHESS and E2E4 on ZX CHESS II. (Continued on p. 84.) Figure 1 : A Game between 7**1 Chess and Z> ZX81 Chess Chess II ZX Chess II •ai D2-D4 G8-F6 ©a 61-C3 D7-D5 03 C1-F4 C8-F5 04 G1-F3 E7-E6 05 P4-G5 B8-D7 06 R2-R4 F8-D6 07 H2-H4 E8-G© 08 E2-E3 H7-H6 09 G5XT6 D6XF6 10 F1-D3 FRV53 11 C2XD3 F6-F5 12 El-Gi C7-C6 13 Fl-El R8-C8 14. R4-R5 F8-E8 15 fi5-ft6 B7-B6 16 G2-G3 B6-B5 17 G1-G2 B5-B4 18 C3-E2 H6-H5 19 El-Hl D7-F6 20 D1-C2 F6-D7 21 B2-83 C6-C5 22 E2-F4 C5XD4 23 C2-E2 D4XE3 24 E2XE3 D6XF4 25 E3XF4 F5XD3 26 F4XB4 D7-C5 27 B4-D2 D3XB3 28 D2-G5 G7-G6 29 Hl-Bl B3-D3 30 Bl-Dl D3-C4 31 D1-D4 C4-B5 32 C4-F4 cex«e 33 F4-R4 R6-B4 34 R4X07 B4-C2 35 R1-R5 B5-B4 36 R5-04 B4-C5 37 R7-R5 C5-C3 38 R5-R7 C8-C4 39 R4XC4 D5XC4 40 F3-E5 C2-E1 41 G2-G1 C3XE5 42 G5XE5 E1-F3 43 Gl-Fl F3XE5 44 R7-R5 E5-D7 45 F1-G2 C4-C3 46 R5-G5 C3-C2 47 G5XG6 F7XG6 48 F2-F3 C2-C1 49 G2-F2 C1-D2 50 F2-G1 D2-E3 51 G1-G2 E3-E2 52 G2-H3 E2XF3 53 H3-H2 G8-H7 54 G3-G4 F3XG4 55 H2-H1 G4-H3 56 Hl-Gl H3XH4 ^7 G1-G2 H4-F4 58 G2-H3 F4-G5 59 H3-H2 H5 -H4 60 H2-H1 H4-H3 61 H1-H2 G5-G2 list YOUR SOFTWARE now for the February catalog SELL IT— SHARE IT You made it to fit your specific needs and it will meet the needs of hundreds of other Sinclair users who will ORDER FROM YOU AT YOUR PRICE software category □ Business Applications □ Educational □ Games ~2 Industrial □ Home □ Helpful Hints Special Hardware if needed designed for □ ZX80 □ ZX 81 /Timex Sinclair 1 000 minimum of □ 1k □ 32 k □ 2k □ 48 k □ 16 k n64k Brief description (100 characters max.) Available as □ Cassette $ _ □ source list $ (US) (US) Name Address Street &# State/Prov Zip/Postal code □ Listing(s) $10: 5£ per listing □ Purchase copy(s) Sinclair Software Sourcebook ($8/4£ ea) □ Check or Money order □ Visa or Mastercharge # .00 .00 exp /_ TOTAL _ Drivers Software Sourcebooks POBox 1048 Port Hardy British Columbia, Canada, VON-2PO 4K ROM; 2K RAM ; 16K RAM House of Horrors Douglas Duchene 7 -*#, You are trapped in the dreaded "House of Horrors." Naturally it is filled with monsters, mummies, skeletons, and strange creatures. Secret passages and mysterious rooms confront you with danger and yet offer the only way out. Your goal is to escape from the house alive. As you move through the rooms, you find various items to help you survive, but you do not know exactly what they will be. So you must depend upon your wits, memory, and logic to escape. The full House of Horrors program requires somewhat over 2K RAM. As a result, it is split into two sections. Type in Listing 1 and SAVE it. Do not kill the program, but enter the changes in Listing 2 and SAVE the program again. Now LOAD Listing 1 from your tape and RUN it. This part of House of Horrors fits into 2K RAM. It can be played as a game in itself for those who have only 2K RAM, and it is a segment of the game for those who have enough memory for the lower level. When the prompt "READY CASSETTE" appears on the screen, you have reached the end of the game if you have only 2K RAM. However, if you have more RAM, set the tape at the beginning of Listing 2, hit NEWLINE, and press the piay button on your tape recorder. When the LOADing is finished, press RUN and NEWLINE to continue your efforts to escape. While the program was written for the 4K ROM, it should not be difficult to translate to 8K ROM. This will require Douglas Duchene, Lot 59 Gatewood, Greenwood, SC 29646. changing the PEEK addresses, the array subscripts, some of the character codes, logical expressions, and the TL$ function, e.g., 310 would become LET R$=R$(2 TO). For users with enough memory the game can be made more complex by increasing the number of rooms and items available. Listing 1. The House of Horrors (Upper Level). 10 REM 1 728630UTS IDE, KITCHEN, B A R , L I V I NG ROD M , D I N I NG R DOM , P IT , L IBRARY, BEDROOM, HALL, KNIFE, SCROLL , W I NE , I- E i , BOOK , ROPE , BO RUNWALCL I J UMGET tAKDROLEALOOOPEREADR I I NVSH A 20 DIM I ( S ) FOR J*0 TO 5 40 LET I =PEEK(J+16427)-28 50 NEXT J 60 PRINT "HOUSE OF HORRORS" 70 PRINT BO LET R»0 90 PRINT "YOU ARE "; 100 IF R THEN PRINT "AT THE " 5 J 10 LET X = 7 120 LET Q«R 122 LET F- 16432 124 GO SUB 9000 1 30 PRINT 140 PRINT "ITEMS HERE:" 145 LET F«0 150 FOR 0*0 TO 5 160 LET P- 16501 165 LET Z«R 170 LET X:=5 175 IF F«l THEN LET Z=0 180 IF I > -Pbt K < P+ 1 ) AND CODE ( TL *(TL*(R*> ) ) =PE! THEN GO TO 3 1 L E I P 230 NEXT J :• Jill " 1 DuNI UNI ND" 60 TO . 310 LET R*»TL*0 THEN GO TO 490 470 PRINT "THERE IS NO WAY TQ G ";R* 480 GO TO 210 490 LET R=R+Z 495 SO TO 90 800 60 TO 400 900 GO SUB 1900 905 IF NOT I»R THEN GO TO 19 70 910 LET I (J>»0 920 PRINT "OK. " 930 GO TO 210 1000 GO TO 9 1100 GO SUB 1900 1110 IF NOT I(J)»0 THEN GO TQ 21 1115 LET I (J)=R 1120 GO TO 920 1200 GO TO 1 100 1300 GO TO 90 1400 PRINT "I CANT" 1410 GO TO 210 1500 IF R*= H SCROLL" OR R*="BOaK" THEN GO TO 1510 80 SYNC Magazine Build your own computer for $ 79.95 The Sinclair ZX81 personal computer kit Imagine building your own computer for only $79.95! That's exactly what you can do with the ZX81 kit. It comes with all the parts you need and complete diagrams and in- structions for putting it together. All you have to supply is soldering iron, solder, and a screwdriver. Plus, of course, a little bit of work. But you get a lot more than several hours of kit-building fun. You also get a surprisingly powerful personal computer. The ZX81 hooks up to any TV for a 32- character by 24-line display (we provide the connecting cables). You can also use a standard cassette recorder to store your programs (again, we provide the cables) Most important, you get a BASIC pro- gramming language that's powerful enough to challenge and interest the most experienced programmers. The ZX81 can handle multidimensional string and numerical arrays. It has full mathe- matical functions accurate to eight deci- mal places. Single-key entry for every command. Syntax error detection, de- bugging codes, and easy editing. Plus features that are ideal for creating games, such as 20 graphic symbols, continuous display, and random number generator. The ZX81 can be expanded too. You can increase the memory' from IK to 16K with our Memory Module for $49.95. And you get a comprehensive manual that completely documents the capabili- ties of the ZX81, and teaches program- ming from the ground up. In short, you get all the features that have made the Sinclair ZX81 the fastest selling personal computer in the world. And you get the satisfaction and fun of building it yourself. A few years ago, this kind of computer power was simply unavailable to the individual. Even today most personal computers are too expensive to buy for personal use. But the ZX81 kit can be yours for only $79.95. Take advantage of this unique offer today. To order, send the coupon along with a check or money order. Or for faster delivery, call our toll-free number and use your MasterCard or VISA, To order call toll free: 800-543-3000. Ask for operator #509. In Ohio call: 800- 582-1364; in Canada call: 513-729-4300. Ask for operator #509. Phones open 24 hours a day 7 days a week. Have your MasterCard or VISA ready. These numbers are for orders only If you just want information, please write: Sinclair Research Ltd., 2 Sinclair Plaza, Nashua, NH 03061. rADCODE~T 09SYOK I MAIL TO: Sinclair Research Ltd., One Sinclair Plaza. Nashua, NH 03061. PRICE* QTY. AMOUNT ZX81 Kit 16K Memory' Module Shipping and Handling $79.95 $49.95 $4.95 lollars TOT AT $4.95 Name Address I City Zip Sinclair technology is also available in Tinu-x/Sinclair computers under a license from Sinclair Research Lid inclair 1505 GO TO 1400 1510 IF R*=" SCROLL" AND I ( 1 ) =0 T HEN PRINT "IT SAYS ESCAPE BY THE PIT" 1520 IF R*="BaOK" AND I<4>«0 THE N PRINT "IT SAYS MAGIC WORD (SHA ZAM) " 1530 IF =PEEK(P) AND COD E i TL$ CR*> ) "PEEK CP+1 ) THEN RETURN 1930 LET P=P+1 1940 IF NOT PEEK(P)»216 THEN GO TO 1930 1950 LET P=P+1 1960 NEXT J 1970 PRINT "I SEE NO " ;R*; 1980 GO TO . 2000 PRINT "IT WAS POISON" 2010 PRINT "YOU ARE DEAD" 2020 STOP 9000 FOR J«0 TO X 9010 IF J=Q THEN GO TO 9050 HERE 9020 LET P=P+1 9030 IF NOT PEEK (P) =216 THEN GO TO 9020 9040 NEXT J 9050 LET P«P+1 9060 IF PEEK (P) =216 THEN RETURN 9070 PRINT CHR*(PEEK0) OR (I<5>>5 AND R*7) ) THEN GO TO 350 350 PRINT "MONSTER WONT LET ME" GO ro 90S IF J 2 THEN GO TO 1130 1130 PRINT "ARE YOU CRAZY?" 1140 GO TO 210 1470 IF R*="DOOR" AND I ( 1 ) =0 THE N GO TO 3000 1480 IF R$="DOOR" OR R*=" CHEST" AND I(1)>0 THEN PRINT "I CANT" 1490 IF R*-"CHEST" AND I < 1 ) »0 TH EN PRINT "ITS EMPTY" 1495 GO TO 210 1500 IF R*="ME" THEN GO TO 2010 1505 IF 1(0) : THEN GO TO 1580 1510 IF R=3 AND R*=" MUMMY" THEN LET I(4)=-l 1520 IF R=7 AND R*=" SKELETON" TH EN LET I <5)=-l 1530 GO TO 210 1580 PRINT "WITH WHAT MY HANDS?" 1585 PRINT "IT ATTACKED YOU" 1590 GO TO 2010 1900 LET P= 16498 2000 PRINT "YOU FELL IN" 3000 PRINT "YOU HAVE ESCAPED" 3010 STOP "THE RIGHT STUFF" ZX-81/TIMEX SINCLAIR 1000 16K GAMES ON QUALITY CASSETTES "BAC-TRAC" A "PACMAN" STYLE PACKAGE OF FUN. 36 GAME VARIATIONS. "FLIPS" A TWO-DIMENSIONAL VERSION OF "RUBIC'S CUBE." FULL SCREEN WITH 99 LEVELS. "ARMEGON" DEFEND YOUR FORTRESS AGAINST THE INVADING ZARDAX. 10 LEVELS OF PLAY. "SUB SEARCH" LOB DEPTH CHARGES AT THE RELENTLESSLY ADVANCING SUBMARINES. MULTI LEVELS OF PLAY. "BREAK-OUT" SINCLAIR VERSION OF THIS TRADITIONAL FAVORITE. MULTI LEVELS OF PLAY. ONLY $6. FOR ANY CASSETTE WRITE; THE LAMBS SOFTWARE 1469AALBORGWAY SOLVANG, CA. 93463 RUBIC'S MASTER FEATURES: Use as Normal Cube Enter User 1 s Cube Scrambles Cube ***Solves Cube*** Save Current Cube For ZX80;8K R0M,ZX81 16K RAM Required On Tape with Instructions JEU INTELLIGENT P.O. Box 71 Glasgow, VA 2Zf555 Price $15 Add $2 for orders outside U.S. in If You Can't Solve It I CAN. SHELF CONSCIOUS? Now you can organize your copies of SYNC Now your magazines can be a handsome addition to your decor, well organized, and easy to find. Thar- these durable library-quality cases or binders. They're made of luxury-look leatherette over high- quality binder board. And both styles are custom signed for this or any other magazine you save, with size, color and imprint selected by the publisher FREE transfer foil included for marking dates and volumes Magazine binders hold a year's issues on individual snap in rods, combining them into one volume $795 each; 3 for $22 50, 6 for $42 95 Mixed titles OK for quantity prices Open-back cases ir issues for individual :e $6 95 each $19 75. 6 for $37.50 Mixed titles OK for quantity p.- For faster sei CALL TOLL-FREE 24 HOURS 800-345-8112 (In PA only 800-662 2444 ) |~SyTc" PO Box 5120. Philadelphia. PA 19141 Please send Q Cases n Binders TITLE Sync Other □ PAYMENT ENCLOSED $_ _.' Add $1 00 per order for postage and handling Outside U. $2.50 per unit ordered: send US funds only | □ CHARGE (Minimum $10) □ American Express □ MasterCard Q Visa 1 Card No | Signature I Print Name— I Address _Exp Date- . City/State/Zip. - - I ' Residents of PA add 6% sales t ax 82 SYNC Magazine M *^J: «S *t^ FOR THE TIMEX-SINCLAIR 1000, ZX81 , (AND ZX80 WITH 8K ROM)! THEZX81 HOME COMPUTER PACKAGE ETCH-A-SCREEN Easily paint pictures anywhere within the top 17 rows. A moving cursor travels up, down, right, left, even diagonally, leaving behind text, graphics, and inverse charac- ters. Keys REPEAT while held down. Your drawing can be stored on tape... and immediately ap- pears when reloaded. Perfect for designing screen logos, or just doodling on the screen COMPOSER BILLBOARD Use BILLBOARD for messages, displays, and exhibits. Type in a message of up to 250 letters, and press ENTER. A row of giant let- ters moves smoothly across the screen, repeating your message until you press NEW and enter a new message. Or, press SAVE and store the message on tape. When reloaded, the message begins au- tomatically. CHECKBOOK BALANCER Keep a running tabulation of your bank account. CHECKBOOK BA- LANCER displays your current checkbook balance, (up to $59,999.99). your latest account balance, and a list of up to 22 transactions which haven't cleared the bank. A plastic-coated keyboard overlay defines ENTER, VOID, CLEAR, and DISPLAY keys. And a SAVE key stores the up- dated program on tape. A keyboard overlay transforms your computer into a four-octave musical instrument which broadcasts music as the keyboard is played. Listen to the music through a radio placed beside the computer, or through an amplifier and speakers. Or record the music directly onto tape. The last 175 notes played are stored in memory, and can be played back or edited. EDIT keys let you change notes and single-step forward or backward through the piece. SPECIAL EFFECTS keys are used to create unusual sound effects like laser blasts and arcade noises. The complete ZX81 HOME COMPUTER PACKAGE, including cassette of four programs, manual, guide cards, screen display sheet, musical score sheet, and TWO FULL-COLOR KEYBOARD OVERLAYS, is just $9.95. Shipping and handling included! $9.95 From: LAMO-LEM LABORATORIES, CODE209, BOX 2382, LA JOLLA, CA 92038 For the ZX81 , TIM EX-SINCLAIR 1000, and 8K ROM ZX80 or MicroAce ITEM PRICE QTY 2X81 HOME COMPUTER PACKAGE $9.95 ZX81 CLASSICS $9.95 ZX81 DISASSEMBLER $9.95 TOTAL m NAME ADDRESS CITY STATE/ZIP Our catalog, with screen display and coding sheets, is free! SIN WARE announces Z EXTRA An original new graphics control pro- gram for the ZX81 or TS1000. Z EXTRA gives you fast machine-lang- uage control of all the standard ZX graph- ics and display features direct from the keyboard. No programming required to create, save, print or display screen after screen of text and graphics. Z EXTRA features blinking cursors, repeating keys, four write directions, eight plot direc- tions, 4x4 and 8x8 character sizes, in- sert, delete and many other convenient functions for creating screen displays. Easy menu selection of single-stroke commands to save multiple screens to tape or in print, display them in se- quence or in scrolls, revise, reorder or search for data entries. Z EXTRA turns your ZX81 into an elec- tronic notebook with a stretch of screen space as long as your memory (RAM). Use it for free-form lists, formatted data files, data displays, moving billboards, etc. Z EXTRA requires a ZX81 or TS1000 with at least 16K of RAM and is especially useful with 64K. Just $19.95 on cassette. HOT Z is an easy-to-use disassembler/ - editor and machine-language monitor that gives your ZX computer the speed and response of a Z80 hot rod. Special entry modes take the tedium out of hex code entry. Extensive debugging facilities let you track down errors fast. Cursor- driven editing functions simplify correc- tions and revisions. Labels let you create annotated listings of RAM or ROM con- tents that stay understandable. HOT Z now runs your ZX printer as well as the cassette for full documentation of your machne-code routines. HOT Z's detailed instructions are ideal for the beginner or part-timer. HOT Z is available for ZX80 or 81 , in ver- sions for 16K or 32K + . Please specify. Only $19.95 on cassette. SINWARE BOX 323, DIXON, NM 87527 ZX Chess vs. ZX Chess II, Continued... Both games make use of the En Passant privilege and display the move as PXPEP (pawn exchange pawn, En Passant). Castling is shown as 0-0 or 0-0-0 depend- ing on the side. If you want to castle, you must enter the king's move. You cannot castle out of check, and both programs stop and report invalid moves. Both allow you to change sides, adjust the level of play, and alter some of the pieces half way through the game. There are some differences. ZX CHESS II allows you to save the present board set-up on cassette, to COPY the screen onto the printer, and to print all the moves that have taken place in that game on the printer. On the higher levels you can even ask it to recommend your next move. As a test to see which was the better chess player, I decided to pit them against each other. I chose level two on both. On this level ZX81 CHESS takes about a minute to decide its move while ZX CHESS II takes about forty seconds. A toss of a coin decided that ZX81 CHESS should go first. Chess enthusiasts will enjoy analyzing the match move by move. The final result was that ZX CHESS II won convincingly, with a Queen, a Rook, a Knight and two Pawn advantage! The final position of the pieces is shown in Figure 1. ^-*— • "" *—-•*. f e-2 o R ZXCHESsBH N I I K CHECK ! MOTE ■■ PLRYER 1 I H1H3 2 O ^ Both games have levels for all players from beginner to postal chess. ZX CHESS II is clearly a better player and has more features than ZX81 CHESS, but it does cost £5-00 more. If you have a OS Char- acter Board, there is a modified version of ZX CHESS II which shows real full- size pieces graphically, and very impres- sive it is, too. S BACK ISSUES OF 5L|n Add to your Sync collection today, while copies are still available. The more com- plete your library of back issues, the more authoritative and useful it will be to you. The earliest available issue is Jan- uary/February 1981, Order any issues you wish, being sure to specify the month and year for each. If a particular issue is out of stock, your payment will be re- funded promptly. Back issues of Sync are priced at $4.00 each, postpaid. Outside the U.S A., $5.00 each. ITyNC DeptNAZS, 39 E. Hanover Ave. Morris Plains, NJ 07950 Please send volumes of Sync listed below Mo. S Vr. Quantity Unit Price Total Price PAYMENT ENCLOSED $_ Mr. Mrs. (NJ residents add 5% sales tax.) (please print full name) City State Zip_ 16k Games (LISTINGS) * * Just $ 3 * * SACK MAN Travel through the maze S A 3 and pick up points. But watch out for the ghosts! — NAVAL COMMAND Seek and des troy the enemy ships. $3.00 each Only $5.00 SOFT BEAR for both! 1455 Canora,Mt Royal Que, Canada. H3P 2J7 V J 84 SYNC Magazine A Mouthful for Every Occasion Don r. Day 4K ROM; IK RAM 8K ROM; 2k RAM You can call up sensational headlines, forceful commands, whimsical state- ments, ageless wisdom, and irrelevant nonsense all at the push of a key on your Sinclair computer with the Mouthful program. What the Program Does Mouthful is a simple text manipulation program based on the old game of draw- ing words randomly from a list of assorted words. Strung together, the words make up an unpredictable and often hilarious phrase or saying. By using the Sinclair computer in a unique way, Mouthful plays this old game in a new way. The program chooses a word from each of the three word lists (see Tables 1, 2, and 3) and prints the resulting phrase on your TV screen. You can generate new phrases as often as you please by pressing NEWLINE. Don R. Day, 980 West McFie, Las Croces, NM 88001. How to Use the Program The program for Mouthful is in Listing 1. Type it into the computer carefully. To begin the operation of the program, type GO TO 20 and hit NEWLINE. If the program is running properly, a string prompt rE") will appear in the upper left corner of the screen. Now comes the big decision: What list will produce the phrase you want? Select Table 1 for oddball headlines, Table 2 for zany slogans, Table 3 for high-sounding 10 GO TO 100 20 DIM A( 150) 30 INPUT A$ 40 FOR N=0 TO 149 50 LET A(N)=C0DE(A$) 60 LET A$=TL$(A$) 70 NEXT N 100 CLS 110 PRINT "PRESS N/L TO GENERAT E PHRASE" 120 INPUT A$ 130 PRINT 140 PRINT 150 PRINT 160 PRINT 170 LET N=*0 180 GO SUB 300 190 PRINT "#"; Listing 1. Mouthful <4K ROM). INCREASE YOUR ZX81 PROGRAMS WITH INFINITY 4 K or more BOUNCY Entrapped by the mad scientist, Count Von Der Bouncy, it is up to you to fight off his bizarre creations known as snogel balls and try to regain your freedom. $7.95* NIGHT DRIVER Test your driving skills on a desert road. Through difficult turns and blinding curves, find out how good you really are. $7.95* CASINO/STOCKMARKET Now you can play the slot machines, keno, roulette, blackjack, and more right in your own living room/then see how well you can deal in the stock market. Be a millionaire in one night, $9.95* MISSILE STRIKE Defend against enemy missies * satellites seeking to destroy innocent cities. You are the commander of a land-based missile defence center. The fate of the world lies in your hands. $7.95* *( All orders should include $1 for postage and handling. Out of the U.S., include $2 for postage and handling.) California residents, please add 6' 2% sales tax. Infinity Research Development 845 Via de la Paz, Suite A 120 Los Angeles, Ca. 90272 200 LET N=l 2 10 GO SUB 300 220 PRINT "//"; 230 LET N=2 240 GO SUB 300 250 PRINT 260 PRINT /'AGAIN? (Y/N)" 270 INPUT A$ 280 IF NOT A$="N" THEN GO TO 10 290 STOP 300 LET I=RND(4)-1 3 10 FOR M=0 TO 9 320 PRINT CHR$(A((N*40+I* 10)+M) ); 330 NEXT M 340 RETURN ZX81 OWNERS SPECIALISED PRODUCTS MODULAR EASY TO USE FOR HOME/INDUSTRY b EDUCATION TE10 INPUT/ OUTPUT PORT - Easy to use Fits between ZX & RAM PACK /PRINTER (if required). No skill required to connect Can be used for such things as:- motor control; sound music generators, connection to printers/floppy discs/ light pens/other computers, temperature monitoring, square wave generating, control of rotating aerials, even train sets etc Port has 16 programmable 1 /0 lines and may be used without any electronics knowledge to connect other add-ons. Motherboard required ONLY when two or more add- ons are used at any one time. FULLY ASSEMBLED $29.50 KIT (WITHOUT CASE) $24.50 TE12 4 CHANNEL RELAY BOX - Tn suit Port Contact rating:- 240v AC/1.5A - 24V DC or 110V AC/3A. L,> to 4 units i.e. 16 relays can be operated $24.50 TE15 8 WAY TRANSISTOR DRIVER - $16.50 TE17 SWAY SWITCH UNIT(EDUCATIONAL) - $21.50 TE18 8WAY INDICATOR UNIT (EDUCATIONAL)- $21.50 TE20 JOYSTICK & FREE GAME - (2 Joysticks may be connected via Motherbon $21.50 TEX MOTHERBOARD Allows multiples combinations of add-ons — up to 16 1 .'0 lines, may be used $26.50 NOTE: TE 12/15/18 Require 9V. 3O0mA Calculator Type Power Supply 23 ♦ 23 WAY ZX Edge Con $5.00 16 WAY SINGLE SIDED EDGE CON $3.50 EXTENDED PIO NOTES $2.50 PRICES INCLUDE POSTAGE Receipts a/ways provided: — Delivery normally ex-stock ADD Full instructions and examples with all products. Send for catalog $1 00. Mastercharge/ Visa accepted SEND S.A.E FOR CATALOGUE. TELEPHONE ORDERS ACCEPTED DISTRIBUTOR INQUIRIES INVITED , THURNAU (ELECTRONICS) ENG ■ '. '.M Of PT V, 95 IIVERPOOI ROAD 1 J CA01SHEAD, MANCHESTER M30-SBG TEL 06 WS 4461 (74 hour) m utterances known as aphorisms (e.g., Necessity is the mother of invention). Type in the list you have selected. Be careful to observe the spaces needed to pad the words into a ten character field. Press NEWLINE after the last word. This stores the words in a single array with proper spacing for random selection. Note that using Table 3 requires some program changes before you type in the list. The screen will go blank for a moment as the . Table 1. Wacky Headlines. . //COMPUTER// BANK// CLERK GOVERNMENT //COMMITTEE PROSECUTOR GENERATES// NABBED// FOR ELIMINATES RECOMMENDS //CONDEMNS// HEADLINES// EXTORTION// EFFICIENCY MODERATION PRISONERS// ZX80 does its prestidigitation. The prompt in line 1 10 will appear and all you need to do is follow the prompts. You can make up your own lists for the Mouthful program. The list must have exactly 15 words. No word can be longer than 10 letters, and, if the word is shorter, add spaces to fill out to 10 characters. After you SAVE a program, use GO TO 100 and NEWLINE to begin exe- cution of the program. Do not use RUN _ Table 2. "Yes, sir!" Slogans. ////CONSUME// OBLITERATE //ADVERTISE ////REWARD//// ////WELCOME// HEALTHFUL// //MENACING// GANGRENOUS //LAVENDER// HONORABLE// VEGETABLES INTRUDERS// HORSEFLESH BEHAVIOR//// //VISITORS// and NEWLINE or you will lose your list. The program can be changed to use longer lists if you have more memory. Lists of 30 words or even more can be entered if array A (line 20) is made larger and the limit of I (line 300) is increased. . Table 3. Words of Wisdom. For Table 3 change Listing 1 as follows: 190 PRINT "#IS THE"; 220 PRINT "#OF#" ////BEAUTY//// ////AVARICE// //NECESSITY ////HONESTY// ////COURAGE// ////SCOURGE// INSTIGATOR ////REWARD//// //BLESSING// //LOATHING// INVENTION// HUMANITY//// ////APATHY//// DEDICATION //AMBITION// Now available in the United States, Britains' best-selling ^^^ ZX81 workstation is a stylish yet practical plinth which will angle your TV to reduce eyestrain, conceal the leads and power supply, and if you have the 16K RAM it will hold it steady to reduce crashes. Moulded in tough black ABS complete with a ready-wired on/off switch. Looks really great J Please order from our U.S. Agent^im Griner P.O Box 1 Princevllle, ILL 61559. Manufactured By Peter Furlong, Product* Unit 5, South Coast Road Industrial Estate. Peace Haven, Sussex, England Tel: (07914) 81637 GET SMART! 0se Smartwaxe software! Ve specialise In providing software for 'full-blown' Tlaax / S i nc lair personal computers. Our progress oan help you realise the fall potential of your machine, for both entertainment and applications* NEW RELEASES: 1, James Bond Adventure #1 1 unique adventure game, in vhioh 70s 1 help 'Agent 007* salts the right deolaione to ooaplete his mission. Of course, 70s will trsvsl to exotio places, fight against overwhelming odds, and hopefully save the world, 2. ZX Tshtsee - The olsssio dioe gams of strategy sad luok f played on a computer. For ons to four players, 5» wharri - Based on an ancient Afrloaa game that waa played with beans and bowls. Sew you will used concentration and earning to outwit the ooaputer, 4. Mailins List / Phone Direotorj - Store the addrees and/or telephone number for up to 100 people. Search for entries in a variety of ways. STANDARD FEATURES: 1. All progress will run on Sinclair ZX81 and Times 1000 oosrputers with 16% of RAM, 2. Sof tears is .hipped on certified error-free data oassettes, with each program recorded twice on the cassette (just in case ons copy gets accidentally erased). ?. Instructions are supplied ss part of each program, rather than on eeparete papere which tend to get misplaced. 4. Bach program is available on cassette, or in listing form (if you really enjoy typing). TO ORDER) Send a check for $9.95 for each oaasstts, or 14.95 for each lieting, tot Smertvexe, P.O. Box 149% Melbourne, Florida 52935 86 SYNC Magazine How the Program Works When you press NEWLINE after typing in the list, Mouthful converts the char- acters into code equivalents which are stored in array A. The trick to breaking this array into three separate lists lies in manipulating the index variable N. This is done by using a multiplier to force N to "see" only that part of the array you want it to. On the first call for a word r the loop index N is set to 0, and a random number is assigned to I. Thus, if I is 3, then the word chosen begins at 0*40 plus 3*10, or at A(30). On the second call for a word, N is set to 1 and I is randomly reassigned. Thus, if I is 5, then the word begins at 1*40 plus 5*10, or at A(90). A third call prints out a random third word by the same technique, and the phrase is finished. Notes The following line notes point out some of the program features. 20-70: Load the word lists into the program as a single variable, A$. 100: Starts main portion of program; return point from line 280. 130-160: Help format display. 180, 210, 240: Calls for the random words. 290: End of main portion. 300: Begins subroutine for word selection and printing. 340: Return to main program. 8K ROM Changes Listing 2 gives the translation for the 8K ROM. The 8K program can also be made to run continuously by deleting lines 1 10 to 290 in Listing 2 and substituting lines 110 to 290 in Listing 3. The 8K ROM version requires over IK RAM to run as shown; however, the continuously running version can be squeezed into IK RAM by shortening array A to about 90 elements and adjust- ing line 320, Short words can be used to maintain the variety of phrasing. HS PRESS ENTER TO GENERATE PHRRSE BRNK CLERK ELIMINRTE5 HEADLINES RGftlN? (Y/N) So . . . Set this program up and have it running at your next party. Your popularity (or perhaps even your notoriety) will never be the same again! Listing 2. 8K ROM. 10 GOTO 100 30 DIM A(150> 30 INPUT A* 40 FOR N=l TO 150 50 LET R(N)=CQDE R* 60 LET R*=R* (2 TO ) 70 NEXT N 100 CL5 110 PRINT "PRESS ENTER TO GENER RTE PHRASE" 120 INPUT R» 130 PRINT 140 PRINT 170 FOR N=0 TO 2 180 GOSUB 300 190 PRINT " "; 200 NEXT N 210 PRINT 260 PRINT TAB 8; "AGAIN? CY^N) " 270 INPUT A* 280 IF NOT A$= "N" THEN GOTO 100 290 STOP 300 LET I = INT (RND*4> +1 310 FOR Hs0 TO 9 320 PRINT CHR* t R ( t N *40 +1 * 10) +M ~9> ) ; 330 NEXT H 34.0 RETURN Listing 3. Lines for 8K ROM Continuous Running. 100 CLS 110 PRINT 170 FOR N=0 TO 2 180 GOSUB 300 190 PRINT " ".. 200 NEXT N 210 PRUSE 120 290 GOTO 100 EVEN IF YOUR LIGHTS GO OUT YOUR COMPUTER WON'T. Introducing NiCd Battery Back-Up Units from Syncware PRICES: Baby BBU — 39.50 BBU-1 — 54.50 BBU-2 — 84.50 • Make your ZX Portable BBU-2 runs over 2 hr. BBU-1 runs 1 hr. Baby BBU runs Vfe hr. • Mairo your ZX immune to line glitches! • Protection against brown-outs, blown fuses, etc. TIRED OF LINE GLITCHES GIVING YOUR COMPUTER AMNESIA? Let Syncware take the annoyance out of computing. Baby BBU and BBU-1 use ex- isting power supply; in case AC line goes dead or power supply gets knocked out of socket, battery takes over until power restored, preventing memory loss. BBU-2 contains built-in heavy duty power supply, eliminating need for original supply. In addition, BBU-2's output is pre-regulated at 8 volts for addi- tional glitch rejection, and also lets your ZX run con- siderably cooler. DON'T WAIT FOR A SUDDEN CRASH BEFORE YOU ORDER YOURS! Hrices are postpaid in continental U. S. Foreign orders — add $5. 00. Payment must be in U.S. cur- rency. Send check, money order or international M. O. only. Tactile Feedback Overht Port ZX 80/61, Time* 1000, or Microace •• TOUCH TYPING POSSIBLE •• STOP MISSED KEfS •• SPEED ENTERING PROGRAMS With our easy to Install keyboard overlay » 3-95 81 ? our Original 16k Programs On a quality oomputer cassette mm TOOK HfTB Addition Subtraction Multiplication and DlTlsion, With flTe levels of achievement In each. Pro» an Introductory level to negative numbers and deolaala.Menu driven, TYPING JKILLS A fun and competitive skill lsprover. You set the speed In words per slnute then try to keep up with the computer. Great with our taotlle feedback overlay I BIRDS Can you guide your missiles to Intercept these horrible swooping creatures, while dodging what they drop? A ghastly end is In store If you are hit, ASTRO SMASHER Pilot your ship through the asteroid belt to find and destroy as many of the oppositions lurking ships as you can before your force shields give out. Careful though, if you hit the wrong part of their ship you blow up. Save the best score and try to better It next time. I 12.50 DUTY PREE Prom 1 P. Bargrave, Site V. RR k, Nanalao, B.C. V9H9C9. Canada ZX TELEPHONE BOOK • Holds 720 names plus easy ADD /CHANGE/ DELETE functions! • Extensive learner friendly documentation even shows you how to add multi-access capabilities 1 • Get this high performance 8K/ 1 6K listing at BIG SAVINGS • Only $4.95 from: THOMAS B WOODS BOX 64 JEFFERSON. N H 03583 STAR VENTURE GAME: Seek out and destroy enemy vessels to move up in Star Fleet ranks. Program listing $2.95 Cassette $4,95 & $1.00 shipping OTHER PROGRAMS AVAILABLE Games, Accounting, and Microwave Cooking Chart for 8K/16K,ZX80/ZX81. DSBC P.O. BOX 1251 DOLAN SPRINGS, ARIZONA 86441 leelly animated adventure ga»e a Mall world. Fight Ronetere te gain power, wealth and Magic ltema, ZX8l/TUex-Slnelair 1000 with 16K or more or RAM. The price la $9.95 Including ■hipping & handling. Daw Software, 78 Aberdeen Pi., Clayton, HO ' hardwarE tips Some Micro Ace Hardware Peculiarities Irving Chalet Problem 1: Keyboard Entry If your MicroAce will not accept key- board entries or will accept some, but not all, the most likely hardware problem is a defective IC Ull, a 74LS365. The solution is to replace it. You must know that the replacement part (either a new 74LS365 original part or a substitute 74LS367) is a good working part, i.e.. it has been tried in a working MicroAce and it works perfectly. I had ordered six 74LS365s from one source, and none worked properly. Even the replacements did not work. Then I ordered from Jameco three types (3-SN74365N. 3- 74LS365, and 3-DM9085N which are equivalent made by National Semicon- ductor). All of these worked fine. Sometimes IC19, a 74LS04, would not allow the computer to accept the shift key entries of + ( - ) > . Changing the IC19, the 74LS04, seemed to correct the problem. Problem 2: Cursor Flicker If your K cursor flickers or if the LS display flickers when the LET command is keyed in, the problem may be a defec- tive IC U24, a 74LS74. The CI 2, a 47PF capacitor, could also be at fault. A good substitute for the latter is a 100PF capac- itor. Spare Chips Since the LS series of chips used in the MicroAce is not expensive, I suggest having a spare set of known good chips on hand. Though you might never have to use them, the assurance of being able to plug in a known good chip balances off the possible frustration of time delay and expense in sending the instrument out for repair. Here is a list of the chips to have on hand: 1-74LS00, 1-74LS04, 1-74LS05, 1- 74LS10, 1-74LS32, 1-74LS74, 1-74LS86. 1- 74LS93, 1-74LS157. 1-74LS163. 2-74LS3h> or 74LS367 or plain 74365, 1-74LS373. Note: be very careful to plug in the chips properly. Pin 1 of the chip must correspond to socket 1. Also be sure to prevent static discharges of your body to the computer. Irving Chaiet. 25 Cherry Hill Rd., New Pali/. NY 12561. 88 References for Troubleshooting The following articles on general hard- ware background and on hardware prob- lems may be of further help. SYNC "Adding an LED Load Monitor to the ZX80 (MicroAce)," (1:1, p. 38). "Four Tips for MicroAce Owners," (1:2, p. 5). "Using the MicroAce with Sinclair Accessories," (1:2, p. 10), "First Aid for Your Keyboard," ( 1 :3. p. 3). "Key Click Generator," ( 1 :3, p. 40). "The ZX80 Keyboard," (1:3, p. 42). "A Parallel Interface for the ZX80/ MicroAce Computer," (1:4, p. 38). "Thick Black Bars," (1:6, p. 2). "Cecil Bridges LED Load Monitor, " (1:6, p. 2). "Experiments in Memory and I/O Expansion," (1:6, p. 20). "Hardware Helpers," (2:1, p. 28). "4K/8K ROMs in One ZX80," (2:2, p. 40). "Getting Loaded," (2:2, p. 41). "Two-Switch Human Interface for the Communicative Impaired," (2:3, p. 23). "Keyboard/System Conversion: The First 40/1 Keys," (2:3, p. 28). Syntax "8K ROM Modification," (2:4, p. 2). "ZZZap! NS74LS365," (2:4, p. 6). "Erratic Keyboard Entries," (2:4, p. 7). "All Purpose Beeper." (2:6, p. 4). "Pull-up Resistors— Keyboard," (2:8, p. 8). "ZX80 Logic States of ICs," (2:9, p. 2). "Video Sync Information and Tape Recording Loading Solutions." (2:9, p. 11). "Trouble Shooting — The Effect of Removal of Each Chip from the Com- puter (incl. chart of equivalent ZX80/ MicroAce IC numbers)," (2:10, p. 3). "Power Plug Blinking Characters," (2:10, p. 9). "SABRE Info on EPROM," (2:11, p. 1). "Improve Video Driver," (2:12, p. 3). Byte Magazine "Memory Expansion for the ZX80," (Jan. 1982, p. 216). "Add Full Size Keyboard," (Mar. 1982, p. 256). "Adding a Reset Key," (Mar. 1982, p. 256). V SYNC Magazine i LET YOUR ZX81 -TIM EX 1000 WORK FOR YOU. All programs On cassette and require 16K Ram Are menu driven and save on tape automatically SALES FILE: Will hold up to 125 products with their wholesale and retail prices Separates and totals wholesale and retail prices and shows the amount of profit in up to 25 different accounts. Records inventory automatically or may be changed manually Keeps a running total of sales tax. Has a cash register mode which will identify, total and add sales tax while it automatically does your bookkeeping "*A must for any small business."* - $19. 95 CHECKING: Lists up to 30 deposits showing amount of deposit and date entered Lists up to 1 00 checks and displays check number, date and to whom check was written Lists by account the total of the checks written to any given account. Keeps a running total of checks wntten and the balance left m your account. '"Great for tax records *" $9 95 MAILING LIST: Holds up to 1 00 names, addresses and telephone numbers Search by name, city, zip code, or phone number to find any address or phone number quickly Lists all names Changes or deletes '"Christmas cards are a snap with this program.'" —$9.95 INVENTORY (1) May be used for every thing from keeping an accurate inventory for your business, to your personal record collection Holds up to 1 50 items with comments for each Comments may be used for serial numbers, dates, prices or location List all items, search for a single item, change or delete any item. - $9 95 INVENTORY (2) Same as above without comments. '"Holds 300 Items."* - $9 95 Three $9.95 programs for 24.95 Add $1 .00 per tape shipping. IN Res add 4% sales tax Send certified check or money order to: HEATH COMPUTER SERVICES 950 East 52 South GREENTOWN, IN 46936 317-628-3130 RUSKR AFT'S ZC ORGANIZER MOLDED OF STURDY, BEIGE ABS, THE ZC ORGANIZER CONCEALS ALL THE ZX01 AND CASSETTE RECORDER CABLES, YET YOUR COMPUTER AND RECORDER ARE READY FOR INSTANT USE. SPACE IS ALSO PROVIDED FOR ADD ON MEMORIES SUCH AS THE 16K SINCLAIR, OR 64K MEMOTEK. GIVE YOUR ZX81 IT'S OWN HOME - JUST $14.95 + $2 SHIPPING/HANDLING SEND CHECK OR MONEY ORDER TO: RUSKRAFT ENGINEERING P.O. BOX 306, DEPT. A TINLEY PARK, IL. 60477 PLEASE ALLOW 4 TO 6 WEEKS FOR DEL. SOFTWARE BY C.E.D.CORPORATION E-Z BOOKKEEPING FOR SMALL BUSINESS (TAKES LESS THAN V2 HOUR PER MONTH). ALSO GOOD FOR HOUSEHOLD BUDGETING. CHECKING ACCOUNT (MAKES CHILDS PLAY OF THIS JOB) BY-IT-SELF ITS GREAT BUT IT WAS DESIGNED TO WORK WITH E-Z BOOKKEEPING MACHINE LANGUAGE NIT-PICK (GREAT FOR LEARNING ASSEMBLY LANGUAGE PROGRAMING) WORD PROCESSOR (IT WAS USED TO WRITE THIS AD) ORDER FROM C.ED, CORPORATION KU. BOX 222, SALEM, WISCONSIN 53168 PRICE LIST E-Z BOOKKEEPING CHECKING ACCOUNT ABOVE TWO AS A PACKAGE ML. NIT-PICK WORD PROCESSOR TAPE LIST BOTH $19.95 $ 8.95 $27.95 $ 9.95 $ 5.95 $14.95 $41.95 $18.95 $ 7.95 $25.95 $18.95 $ 7.95 $25.95 SPECIFY ZX80- 1 OR TRS 80 COLOR COMPUTER ZX80-VS NEED 16K RAM TRS 80 NEEDS 16K RAM ALL OF OUR PROGRAMS ARE MENU DRIVEN AND ALL DATA CAN BE STORED ON TAPE AND OR SENT TO A LINE PRINTER WE HAVE TELEPHONE SUPPORT FOR PROBLEMS OR QUESTIONS CALL (414) 276-8787 ITS HERE!!! THE NEW KEYBOARD YOU'VE BEEN WAITING FOR! A 60 KEY TACTILE FEEL KEYBOARD THAT PLUGS INTO ZX-81 OR TIMEX SINCLAIR 1000. INCLUDES ALL SILKSCREEN LEGENDS IN 3 COLORS. GRAPHICS AND LEGENDS MOULDED IN KEYTOPS. 8 ADDITIONAL KEYS FOR EDIT, DELETE, QUOTE, FUNCTION, "":; STOP. (NO SHIFTING REQUIRED). MEASURES 10"X4". HAS 5" SPACE BAR, TWO SHIFT KEYS AND A NUMERIC KEY PAD. $70.00 MASS RESIDENTS ADD 5% SALES TAX SHIPPING & HANDLING $4.00 PER UNIT DELIVERY 3-6 WEEKS. QUANTrTY DISCOUNTS FOR USER GROUPS. ACCEPT M/C, VISA #s. INCLUDE EXP. DATE & SIG- NATURE. FOR MORE INFORMATON SEND SASE OR TO ORDER SEND CHECK OR MONEY ORDER TO: E-Z KEY SUITE 75 711 SOUTHERN ARTERY QUINCY, MASS 02169 EDSON ELECTRONICS OFFERS Educational programs for grades 1-4 that reinforce what they learn in school. We also offer a digital dis- play load monitor for monitoring data from the cassette to the computer. Write to Edson Electronics P.O. Box 151211 Tampa, Fl. 33684 for free info. ZX81 Software Plotter 1 — A sophisticated routine that plots and graphs any function (16K) $9.99 (U.S.) Two Handed Euchre — Challenge the computer in this entertaining and skillful game (64K) $14.99 (U S ) J.C Software 28 Shipley Rd Weston. Ontario, Canada M9R-3H8 ZX-80 8K ROM USERS Completely expand your ZX-80 with 8K Rom to a ZX-81 with full use of Fast and Slow. Smooth flicker free per- formance! Complete Kit: $32,50 & $2.50 postage & handling; PCB only $19.95 & $1.25 p&h; Parts Kit Only$12.55&$1.25p&h. The Expandable ZX-80 and ZX-81 A book of hardware projects that you can build yourself, from memory ex- pansion to speech synthesis. Only $9.95 & $1.25 p&h. Program writers: We publish software and complete books. Write for details. COZDPUTffl ENGINEERING SEW71tt5 The Jarrett Company (Dealers Inquiries Invited) CUSTOM ATTACHE CASE FORM FIT FOR ZX80/81, TIMEX SINCLAIR 1 000 AND HARDWARE. FOR INFORMATION SEND SASE. TO: COMPUTA-DEK 6009 KENWOOD DRIVE NASHVILLE, TENNESSEE 37215 ZX81/16K ADVENTURE GAME — $9.00 With cassette and manual ADVENTURE GAMES #10-35 St. Des. Moines, la 50312 Keyboard Bleeper — no soldering required. $19.00 total. Loading Aid — ZX80/2X81 /timex 1000 $21 .00 total T-Shirts — red "Sinclair ZX81" on black. State size. $7.00 total. Fulcrum Products, Dept. U Hillside Steep Lane Findon, W. Sussex, England BN14 0NF 8K ROM Updates In the first issues of SYNC the programs were all for the 4K ROM. When the 8K ROM became available, we tried wherever possible to provide listings for both ROMs, Since we have had requests from readers for updated versions of some of the programs we published earlier, we will include these from time to time. Translated to 8K ROM by James Grosjean, 50 Kings Rd., Chatham, NJ 07928. Hurkle Laura McLauglin The Hurkle is hiding deep in the forest and you must find it by logical deduction. Type in the program, hit RUN and ENTER. The prompts will call for the input of two coordinates (X,Y) corres- ponding to a point on a 10x10 grid. The computer will then tell you in which direction the Hurkle is hiding. Again you enter a new set of coordinates and con- tinue until you have found the Hurkle or used up your five guesses. The program fits in IK RAM. With sufficient RAM, Hurkle could be expanded to show the grid on the screen and record your entries. 1 CLS 2 LET R=INT l'RND*10) +1 4 LET B=INT IRND410MI 6 FOR K=l TO S 8 PRINT "GUESS NUMBER ";K 1® PRINT "X COORD?" 12 INPUT X 14. PRINT "Y COORD?" 16 INPUT Y 18 IF fiBS (X-RJ + RBS CY-B> =0 TH EM GOTO 4-8 20 CLS 22 print "X«";X;" y = ";Y;" "; 24- GOSUB SCt 26 NEXT K 38 PRINT "SORRY, THRT IS 5 GUE S3ES. " 32 PRINT "PLOY RGRIN"?" 34- INPUT R$ 36 IF NOT CODE R*=62 THEN STOP 38 RUN 48 PRINT "YOU FOUND HIM IN ";K " GUESSES." 42 GOTO 32 58 PRINT "GO ", 52 IF Y«B THEN GOTO 62 54 IF Y +1 28 LET fi=0 30 LET E=RND*50+1 32 LET F=INT C THEN GOTO 94 114 IF 0>^R THEN LET C=C+G display will continue to confront you with options which will either use up your strength or add to your strength. When you feel your strength is sufficient, you may take on the wizard. The variables in lines 26-34 may be changed to provide different challenge levels. 116 IF ©>=R THEN PRINT "YOU Ulf BRRUE RDUENTURER" 118 IF Q=£ THEN LET C=C-P+G 140 IF P>=E THEN PRINT "ftCCEPTE D" 142 IF P=B THEN PRINT "YOU KIL LED THE UIZRRD-YOU WIN" 182 IF C"Y" THEN GOTO 4-10 390 LEI Pi =P + 1 400 LET H = =H-1000 4-10 PRINT "flD BUDGET IN 10005 4.20 INPUT B 4 30 IP B*10>M THEN GOTO 4-20 440 LET M=M-B*10 4.^0 PRINT "PRODUCTION IN 1005 470 480 490 500 510 520 530 550 560 570 600 610 620 630 640 550 660 INPUT U IP UU0JP THEN GOTO 470 LET I=I+U LET 5= INT (S/INT IP B<& THEN GOTO 55© LET 3=S+(B-6)*5 LET B=6 IP B<2 THEN GOTO 600 LET 5=5+ CB-2* *7 LET B=2 LET S=S+B*8 IP 5>I THEN LET 5=1 LET M=M+S*I0 LET 1=1-5 LET M=M-20*P-20 LET M=M- (U-U #8 IP M>=0 THEN GOTO 100 PRINT "YOU ARE BANKRUPT." SYNC-hronizing Education and Games A newsletter filled with games and ideas for the Sinclair. A Quarterly publication that is a must for all Sinclair owners. Send $7.00 U.S. $8.00 Canadian to: SYNC-hronizing Education and Games c/o Henry Svec 668 Sherene Terrace London Ontario Canada N6H 3K1 (Cheques payable to Henry Svec) IS YOUR FAMILY TIRED OF PLAYING GAMES ON YOUR MICRO? ARE YOU LOOKING FOR WAYS OF CHALLENGING YOUR INTELLECT? QUIZ WIZ IS THE SOLUTION! Through QUIZ WIZ you can test your family s general knowledge on your 16KZX81. INTRODUCTORY OFFER! FIRST ISSUE Two Quizzes Per Cassette $4.37. OR BETTER YET! Full Year Subscription Six Issues-Six Cassettes $22 47 Send check or money order to: S.C.I. Box 553 Mechanicsville, Virginia 231 1 1 Virginia Residents add 4% sales tax Overseas orders add S1 .00. ADD ON MEMORY FORZX 16K memory assembled and tested. No extra power supply needed. 90 day warranty on parts and labor. $45.95 POSTPAID Check or money order only. California residents add 6%. KB ENTERPRISES 8211 VALDOSTAAVE. SAN DIEGO, CALIFORNIA 92126 September/October 1982 91 resnurczES The "Resources" column lists new products for Sinclair users. Suppliers and users are invited to send brief product descriptions and details for ordering to: Resources, SYNC, 39 E. Hanover Ave., Morris Plains, NJ 07950. User Groups • Kaiserslautern, Germany ZX81 Users Group. Just being started. Contact: Tom White HG 21st SUPCOM ACSRM - IRD APO NY 09325 Phone: 2221-7432 • The Sinclair Users Group of San Diego. For information contact: Robert Jorgenson 3814 Coleman Ave. San Diego, CA 92154 User Groups Forming • Any Portland, Oregon, area users inter- ested in forming a group? Contact: J. E. De Groot 2146 N.W. Johnson St., 108 Portland, OR 97210 Business/ Household Programs • ZX Phone Book. Holds 720 names with edit functions of ADD, CHANGE, DELETE, and SAVE; search by name or category; can be used for other information. 16K RAM. Hard copy listing with thorough documentation: $4.95 • Sort-a ZX8L Collating tool; counts and files thousands of items in up to 29 categories on just IK RAM; listing and notes show how to use your ZX81 as a home and office tool. Hard copy listing with thorough documentation: $4.95. Thomas B. Woods PO Box 64 Jefferson, NH 03583 • Data Storage and Display System. Stores up to 60 data points in a file, e.g., stock prices, profit-loss data, experimental data; allows file crunching for plotting; 92 up to 25 files can be saved under user- defined titles; recalled in tabular or graph form; menu lists 9 jobs; expand- able with additional cassettes. 8K ROM; 16K RAM. $14.75 plus $1.25 s&h. ZX-Panding, Ltd. PO Box 25 Newton, NC 28658 Educational Programs • Vocab Builder for the ZX8L 60 words per cassette; 2 modes; definitions and quiz; for teens and adults. 16K RAM. $9.50. Charles Bucher 132 E. Pasco Lane Cocoa Beach, FL 32931 Games • ZX81 Bomber. Drop bombs and two types of missiles on the enemy; graphics; points and percentage; full documen- tation and instructions. 8K ROM; IK RAM. Program: $1.00 plus SASE. Cassette: $3 plus $1 s&h. Rimas Buntinas 7440 N. Rockwell Chicago, IL 60645 • Trader Jack. You are captain of your own trading vessel sailing the South Pacific; buy supplies; fight storms and volcanos; trade your cargo, hopefully for a profit. 8K ROM; 16K RAM. Also ZX81 Monopoly in Spanish, American, or British versions. Each game on cas- sette: $14.95. Savage Software PO Box 892 New Smyrna Beach, FL 32069 • Pick em. Program to attempt to predict outcome of national football league games and even the point spread; accepts information available from most daily newspapers. 8K ROM; 16K RAM. Cassette: $9.95 plus $1.50 s&h. Stuart Software 25381-G Alicia Pkwy., Suite 316 Laguna Hills, CA 92653 • Mad Dog Tank Blaster. Mammoth pro- gram with routines useful in your own programming. Wild tank moves through grid-like maze blasting all the way ; your man must put a mine in its path without getting shot, run over, or blown up by the mine. Hard copy listings with thorough documentation to teach pro- gramming. 16K RAM. $6.95. Thomas B. Woods Box 64 Jefferson, NH 03583 • Arcade excitement on your IK or 2K ZX81. All programs have moving graph- ics; sold as listings. Pickle Man: $2 Tempestuous Battle: $2; ICBM Barrage $2; Monkey Barrels: $2; Defense Wave $1.50; Evade: SI; Lander-X: $1.50. Add $0.30 s&h. Panero Software 3309 Lewis Ave. Long Beach, CA 90807 • Game Pack for the ZX81. Bomber (move the bomb sight over the target, very fast); Missile (destroy the missiles before they hit your spaceship); Auto 3- D (enter 4 numbers; ZX81 will draw tunnels and spirals and much more depending on numbers); Speed Draw (the ZX81 starts a line; control it by the right keys to produce all sorts of pictures). 8K ROM; IK RAM. All four on one cassette: $5 plus $3 s&h. Mark E. Rogers 553 Melrose Dr. LaPlace, LA 70068 • 18 Hole Golf Graphics display of each hole, moving ball, 3 types of hazards; 4 player capability; final score card dis- play; 3 different courses. 8K ROM; 16K RAM. Cassette: $10. R. Midura 19 Merrifield St. Worcester, MA 01605 Graphics Programs • Memopak High Resolution Graphics. Contains 2K EPROM monitor, holding full range of graphics subroutines called up by USR or machine code; gives 192 x 248 pixels. Video pages: each requires about 6.5K RAM; memory and bit mapped; can be located anywhere in available RAM. $149.95. Memotech 7550 West Yale Ave., Suite 200 Denver, CO 80227 SYNC Magazine KEMPSTON MICRO ELECTRONICS %n® Ne ZX KLIK - KEYBOARD IF YOU ARE like many ZX81 users and are fed up with the dead 'touch sensitive' key pad then consider the advan- tages of the new KEMPSTON KLIK-KEYBOARD. This is a genuine push button keyboard which has been designed as an exact replacement, being no larger than the existing key pad, but offering all the advantages of a full size keyboard. Consider these facts: • FitsontotheZX81, •No soldering needed on the assembled version (just plug in) •No trailing wires. •No special case required. •Positive feedback from keys. •Full two colour legends supplied. • Full back-up service offered, including fitting. This is a genuine 40-key, push button keyboard which fits into the recess formed after peeling off the existing touch sensitive keypad. The kit comes with a precision drilled P.C.B. finished in matt black, 40 keys, 2 colour legends, connecting tails, adhesive pads and a full set of instructions. Also available from our range of products is a Parallel User I/O post £16.50 built & tested. Gives 16 I/O lines to drive light relays, motors etc. Many already sold to education. Keyboard bleeper £8. 95 built. Your Name and Address Qoam,r r Description Unit pds rripston. Beds MK^PBOZ Proprietor A. Pandaal, B.Sc, P.G, Cert. Ed. A a Peak / Vcassette Software for the 8K ROM, 16K RAM Sinclair BLACKJACK - Practice your strategy. Hit, stand, double down, split and take insurance with this Nevada casino game* Plays out a complete deck, $10 TEXT - A program for easy text editing, storage and display. Recall pages of text without splitting words at the end of a line. PRODIR - A programmed directory to organize programs and ease loading. Both TEXT and PRODIR for $10 Prices include shipping. Send check to: Peak, P.O. Box 383, San Carlos, CA 9l|0?0 MAKE YOUR SINCLAIR A PORTABLE COMPUTER SYSTEM MAC (MOHR & Associates Corporation) Now Of- fers You A Durable, High Impact ABS Plastic Brief- case That Measures MVi'X 12 1 /4"X4V 2 ". Wired For 1 10-60HZ And Ready To Be Used! You Merely Insert Your Sinclair Components (In- cluding Printer) In the Preformed Cavities And BINGO You Have A Portable Computer System The Briefcase Has Slots For Tapes, Coax Cable And The TV Adapter. $149.95 Includes Shipping & Handling. Kansas Residents add 3% Sales Tax. TO ORDER SEND CHECK OR MONEY ORDER MOHR & ASSOCIATES CORP 645 N. Baltimore Derby, KS 67037 (316)788-1526/788-3165 MC/VISA ACCEPTED ZX TYPING TUTOR • LEARN ALPHA NUMERIC KEYBOARD • THREE SKILL LEVELS • INSTANT FEEDBACK AND FINAL SCORE • GET THIS HIGH PERFORMANCE 8K/16K LISTING AT BIG SAVINGS. • ONLY $4.95 FROM MICRO-TECH 1019 BRANDON LAKES AVE VALRICO. FLORIDA 33594 MARKETING SERVICES For those unfamiliar with techniques in mar- keting methodology Send us your original programs for review Send S.A.S.E. for full details, now Timex Software Company Box 48595 Chicago. Illinois 60648-0595 The Troiano Software Company is now offering for the ZX81 a graphics, games, accounting, math and utility package with 12 programs in all! Only $4.00. Troiano Software Company PO Box 40 Nesconset. New York 1 1 767 ZX81 Assembler 2 Pass Standard Mnemonics, Symbolic expressions, Decimal / Hexadecimal. 12K Basic and machine code. ZX81 Disassembler Standard Mnemonics, Decimal / HEX S18.00 for both programs postpaid Bob Berch WJaques St. Rochester, N.Y. 14620 Catalogs/Directories/ Product Lists • Programs for the ZX81. Games, business, household, statistics, cards, aids, horse racing, and other general items. Free catalog. UAS PO Box 612 Haddonfield, NJ 08033 • Game, utility, household programs. 16K RAM/ IK RAM. For details send SASE (postage $.40). Gampper Zollamtstrasse 52 675 Kaiserslautern West Germany • The Sinclair Computer Family Sourcebook. Lists over 500 programs, books, accessories from over 80 manu- facturers. $4.95 plus $1.25 s&h (add 4% tax in Virginia). Atlantic Computer Products PO Box 936 Norfolk, VA 23501 • Howard Hein is compiling a directory of services and supplies for the Timex/ Sinclair 1000. He invites readers to supply information on: hardware and software suppliers; hardware and soft- ware projects (including listings); user groups; newsletters; reviews in maga- zines and books; suppliers of training; shows and festivals. Submissions and comments to: Howard Hein 33 Oak Lane Mt. Lakes, NJ 07046 RAM Expansion • Memopak 16K RAM. Accepts further memory units plugged in "piggy-back" fashion (Memopak 16K, Memopak 32K, or Sinclair 16K) and other add-on peripherals. $59.95. • Memopak 32K RAM. Full 32K RAM directly addressable. Accepts Memopak 16K RAM as plug-in. $99.95. Memotech 7550 West Yale Ave., Suite 200 Denver, CO 80227 94 Printers • MW 100 Printer. Available now. Prints on plain paper roll, 1 3/4 inches wide; standard tape and ribbon obtainable at office equipment and electronics stores. For details: Mind ware, Inc. 70 Boston Post Rd. Wayland, MA 01778 (617) 358-7175 Interfaces • Memopak Centronics Parallel Printer Interface. Enables ZX81 to be used with a wide range of dot matrix and daisy- wheel printers. Resident software gives ASCII character set. $94.95. Memotech 7550 West Yale Ave., Suite 200 Denver, CO 80227 • ZX99 Automatic Tape Control. Full software control of up to four tape decks (two for loading; two for saving) to mix and modify files; uses tape for data storage; automatic tape copy; diagnostic information for best recording; RS-232- C interface to connect to any such serial printer using standard ASCII; 2K ROM extends the ZX81 8K ROM and accessed by USR. $150. Data-assette H.S.W. & S., Inc. 52 South 3rd St. Oxford, PA 19363 (215) 932-3626 Keyboards • ZX80/1 Keyboard. Key tops finger shape molded; characters for the ZX keyboard printed in two colors on key- tops as per your ZX80/1 ; repeat key; black plastic molded case available (can be purchased separately); 12-inch ribbon cable attached by 15 solder connections; full instructions. $75. Data-assette H.S.W. & S., Inc. 52 South 3rd St. Oxford, PA 19363 (215) 932-3626 • 44 key tactile keyboard; plugs into ZX81 or Timex/Sinclair 1000; all graphics included; EDIT, DELETE, M , and FUNCTION do not require shift. $70 plus $4 s&h (add 4% tax for Massa- chusetts EZKey Suite 75, 711 Southern Artery Quincy, MA 02169 SYNC Magazine I • Keyboard overlay. Gives tactile help in making keystroke entry; stops missed keys; speeds program entry; simple to install. $3.95. P. Hargrave Site V, R.R. 4 Nanaimo, B.C. Canada V9R 5X9 • E-Z Key 44. Hear a click and feel a snap for every key pressed; 4 special keys have electronic control to eliminate need to use shift key (DELETE, EDIT, H , FUNCTION); accesses all graphics and functions; no wiring required; just plug it in; adaptable to ZX80 or Micro- Ace; schematic and instructions. $70 plus $4 s&h (add 4% tax for Massachusetts. E-Z Key Suite 75 711 Southern Artery Quincy, MA 02169 Hardware Improvements • ZX81 Improved Heatsink. Prevent sys- tem crashes caused by overheating of voltage regulator; no modification of appearance or function of the ZX81 needed; installed in minutes. $10. B. Sanzone 289 Baxter Lane Milford, CT 06460 • End edge connector tarnish problems. Electro-plate the fingers with 24 karat gold. $15 plus $3.75 s&h for first item; $10 plus $2.75 for any additional item with the same order. Do not send the product you want plated now. Instead send SASE for full details first. Matthew Zenkar 142 Holcroft Rd. Rochester, NY 14612 System Expansion • System expansion kit. Install permanent system utilities such as machine lan- guage or service routines in up to 8K memory that is not lost when you reset or turn off your ZX81; compatible with 16K RAM packs. Full details and all components including one 2K HM6116P-3 CMOS RAM: $29.95 plus $1.95 s&h. PC board alone, masked and silkscreened: $15 postpaid. Additional 2K HM6116P-3 (150 ns): $9 each. Hunter 1630 Forest Hills Dr. Okemos, MI 48864 September/October 1982 Tape Accessories • Winky Board Cassette Loader/Dupli- cator Interface. Makes loading easy; includes LED level monitor, earphone eavesdropper and interference filter, circuits for direct copying of any cas- sette. Kit: $12; assembled and tested unit: $18. U.S. postpaid; overseas: add $2. Free information. G. Russell RD 1, Box 539 Centre Hall, PA 16828 • ZX Loading Aid. Circuit detects and shows signal level on two LEDs to enable you to distinguish program, intro- ductory buzz, silence, voice overs; in small black metal box 90x35x30mm with two 3.5mm sockets and two 3.5mm jacks; connects between tape player and computer. 1%9.95 (incl. s&h and VAT); $21. Specify which computer you will use it on. Fulcrum Products "Hillside" Steep Lane, Findon Worthing, West Sussex BN14 0UF United Kingdom • Chirper module. Gives acoustic feed- back on keystrokes as a variable chirp that remains on until the ZX81 is ready for another entry; produces sound while program runs; sounds can be program- med either in Basic or machine code; fits inside ZX81; solder 3 wires. $9.95. Audiograph Co. 3584 Leroy Ann Arbor, MI 48103 T-Shirts • T-Shirts and Sweatshirts. Soft WEAR for the ZX81 owner. T-shirts with round neck and short sleeves; sweatshirts with long sleeves and heavy weight fleecy lining. Red lettering "Sinclair ZX8r on black or white shirts. Adults: 34", small; 36", medium; 38-40", large; 42-44", extra large. Children: 24", 26", 28", 30", 32". T-shirts: £3.25 or $7; sweatshirts: £6.99 or $16. Fulcrum Products Hillside, Steep Lane Findon, Worthing West Sussex BN 1 4 0UF United Kingdom Video Upgrade • Video Upgrade Kit. For ZX80 8K ROM; smooth flicker free video; performance is exactly that of the ZX81 ; easy assem- bly and installation inside the ZX80. $32.50 plus $2.50 s&h. Computer Engineering Services POBox 1222 Show Low, AR 85901 (602) 537-7522 8K ROM; 16K, 1K. Games, Utilities, Tech prog., Household prog. & more. For details send SASE to: NGM INC. P.O. BOX 18702 OKLA CITY, OK 73154 COLOURSCREEN FOR TIRED EYES Fit one of our colourscreens to your TV. and cure those programmers eyes. Available in 3 sizes and 5 colours. Blue, Green, Red, Yellow and Orange. Small (9" x 12") $1. 75 Medium (1 2" x 15") $2.95 Large (18" x 24") $4.50 Plus $2.00 airmail postage Order now direct from the U.K. Ellanbee (Graphics) 1 1 Lichfield Close, Great Lumley, Chester-Le-Street, Co. Durham DH3 4QHU.K. 2X-81/1K Listing of 5 games $2.00 Solo 2 Player Games 2 Graphic Displays, Stock Market, Random Race, Treasure Hunt. 2-Games P.O. Box 367 Ringles, N.J. 08551 CAR LOG A new USEFUL suite of professional programs for the ZX8 1 ( 1 6K). 1.) Very simple to use with full instruc- tions. 2.) Complete cassette record of mileage and itemised expenses. 3.) All conceivable ratios, totals and projections computed. CAR LOG is suitable for your car, your dad's car or your whole fleet of trucks. Only $14.95 NIMRODSORTWARE 4 Stanley Rd., London, SW1 4 7DZ U.K. NEW for your ZX 81 Microtronics-LR, inc. is introducing a new peripheral for the Sinclair ZX 81 soon! Watch for our ad. VOYAGER ADVENTURE Your space craft has landed on a barbaric planet, attempt to save your own planet Here you will meet up with more than 20 different encounters You ll have your choice of one of over 34 billion characters available This adventure is huge (two sides- 16K each) and is saveableonce in progress Send S9 95 or for more, send to Chris White. 789 S Greenbay Rd . Lake Forest. IL 60045 95 PLANET FINDER FOR THE 16K TS-1000/ZX-81 MERCURY, VENUS, MARS, JUPITER and SATURN are all visible to the naked eye. The ancients recognized that their special quality is that they move against the background of "fixed" stars. Predicting their movements has been the preoccupation of geniuses for thousands of years. Now these movements are well understood, buy only by a few dedicated observers. Ephemeris V is designed for these people and others (ages 12 and up) who wish to join them in this pursuit of basic knowledge. 1 6K reqd. ENTER: date, time, lat. and long. (Lat. and long, can be perm.) Then choose a planet. In seconds Ephemeris V responds with: 1. Azimuth and Altitude 2. Right Ascension and Declination (for astronomers) 3. Simple compass coordinates (for beginners) 4. GRAPHIC DISPLAY of planet in current constellation 5. LOCAL sidereal (star) time to aid in finding stars, comets, nebulas, etc. Own or give this incredible program and reap the harvest of real understanding forever! Comes on quality cassette with docu- mentation. Send a money order or check for $8.00 ppd. to: EPHEMERIS V, P.O. BOX 261 , Winchester, KY 40391 . MUSIC and KALEIDOSCOPES VIRTUOSO. A music synthesis program for the Timex/Sinclair and ZX81 with 2K or more. NO MUSIC KNOWLEDGE NECESSARY! 96 notes, range from put put to above treble clef, any tempo. Whole to 32nd notes. Songs may be saved for future use. Required hardware? - - Your cassette recorder. $6.95 pp. PLAYER ZX81. A less versatile music program for 1 K memory. To: Music knowledge unnecessary. $6.95 pp. SQUARES and CROSSES, Kaleidoscopic simulations for the same machines. 1K or more. $6.95 pp. All on standard cassette. Guaranteed to load. Music programs include random sound listing or save copy. Add $3.00 each, outside U.S. Mr./Mrs./Ms. Address City /State/Zip Virtuoso $6.95 Player ZX81 $6.95 Squares & Crosses $6.95 William Don Maples 688 Moore St. Lakewood, CO 80215 CHECK QUANTITY Aardvark...... — 41 Abersoft . 43 Active Designs 32 Acts Audio 77 Adventure Games 90 Aerco 43 Altex 39 Apropos Tech 65 Atlantic Computer Products 60 Audiograph 54 Balogh, John 91 Baiiog Software 76 Berch, Bob 94 Biocal Software 91 Bi-Pak 23 Byte Back Co 35 CAI Instruments 17 C.E.D. Corp 89 CSI Company 78 Cleva Computer Ware 33 Computa-Dek 90 Computer Continuum 64 Computer Engineering Services 90 Computercraft 60 Cook Labs. 51 Cosmonics , 68 DK Tronics Cover 3 DSBC 88 Data Assette 4, 5 Daw Software 88 Double H 45 Down East Computers 76 Downsway 63 Driver Software 79 E-Z Key 89 Edson Electronics 90 Ellanbee Graphics 95 Ephemeris V 96 Ezra Group II 21 Florida Creations 10 Fritsch, D 78 Frog Software 61 Fulcrum Products 90 Fuller Micro 74 Furlong, Peter, Products 86 Gibbons, J P 57 Index to Advertisers Gladstone Electronics. 48, 49 Hargrave, P 88 Haymarket Software 63 Heath Computer Services.... ... 89 Hunter 61 Hurricane Electronics 56 Independence Research 18 Infinity Research 85 Intellectual Games., 91 Intercomputer, Inc .... 13 International Publishing 3 1 J C Software 90 JEU Intelligent 82 JK Audio 16 JRS Software 12, 19 Jenn Products 45 KSoft 46 K B Enterprises 91 KM L Incorporated ... 73 Kayde Electronic Systems.. 2 Kempston Electric 65 Koala Softbear... 84 Kopack Creations, Inc 67 Lambs Software 82 Lamo Lem 83 Leading Edge Cover 4 M.C. Associates 52 Macronics 40 Maples, William 96 Memotech 9 Micro-80 73 Micro Computers Plus 27 Micro Design Concepts 56 Micro Sync 7 Micro Tech 94 Microtronics 95 Mikro-Gcn 57 Mohr & Associates 93 N G M Inc 95 Nimrod 95 Nirad 57 Non-Trivial Solutions.. 8 Nooter Stock Program 59 Oasis... 65 Omni Technology 43 Overbyte 46 P & B Software 91 Panda Software 22 Peak 93 Powertronix 94 Reston Publishing.... 37 Robill Products ... 59 Rom Pac Applications .Cover 2 Remark ... 18 Ruskraft Engineering 89 S.C.I 91 Savage Software 91 Servitronics 73 Sinclair Place 28 Sinclair Research 14, 15, 81 Sinware 84 Smartware 86 Softclair 60 Softsync Inc 1 Software Master 47 Southern Computer Systems — 25 Strategem Cybernetics 64 Stratos 93 Svec, Henry 91 Synchronize 32 Syncwarc 87 Synergistic Design 1 1 T.V. Services 54 Thurnall 85 Time Data 12 Timex Software 95 Troiano Software.. 94 Turner, Elcy & Com 38 Upsystems 61 White, Chris 94 Wisconsinc. 69 Wolfkamp 72 Woods, Tom 88 York 10 45 Z Games 95 Z Ware 60 Zeta Software ■ 77 Zodex 63 Zor Khan Industries 59 ZX Panding 68 Z-West 76 VI "* .lot*, n CCn >& !-♦ -I l J J© "* => = e^ £ o ^ ^i ^ O J ^^ T3 *i r £ q} IS in dm >g- Si as d Si%fc .--2 *A > ! C U 1 ^ F *- u OfZrN 0; E^^n £ ro en >*-p jj ~ £ fa £ H3 £ y ^ y ot" c 2 2 ^ 5f o *- ^ Q.&E CTth- Cl5 E *- Sr ^ O - qj (Li e e: qi e; e I 6 1 ! ol ol I II D>Q_Q_D-CL.Q-Z< ^ o s ^ i t u5Un CO U THE PROWRiTER COMETH. (And It Cometh On Like GangbustersJ Evolution. It's inevitable. An eternal verity. Just when you think you've got it knocked, and you're resting on your laurels, some- body comes along and makes a dinosaur out of you. Witness what happened to the Centronics printer when the Epson MX-80 came along in 1981. And now, witness what's happening to the MX-80 as the Pro Writer cometh to be the foremost printer of the decade. SPEED MX-80: 80 cps, for 46 full lines per minute throughput. PROWRITER: 120 cps, for 63 full lines per minute throughput. GRAPHICS MX-80: Block graphics standard, fine for things like bar graphs. PROWRITER: High-resolu- tion graphics features, fine for bar graphs, smooth curves, thin lines, intricate details, etc. PRINTING MX-80: Dot matrix business quality. PROWRITER: Dot matrix correspondence quality, with incremental printing capability standard. FEED MX-80: Tractor feed standard; optional friction-feed kit for about $75 extra. PROWRITER: Both tractor and friction feed standard. INTERFACE MX-80: Parallel interface standard; optional serial interface for about $75 extra. PROWRITER: Available stan- dard-either parallel interface or parallel/serial interface. WARRANTY MX-80: 90 days, from Epson. PROWRITER: One full year, from Leading Edge. PRICE Hen, heh. Marketed Exclusively by Leading Edge Products, Inc., 225 Turnpike Street, Canton, Massachusetts 02021. Call: toll-free 1-800-343-6833; or in Massachusetts call collect (6171828-8150. Telex 951-624. LEADING For a free poster of "Ace " fProwriter's pilot} doing his thing, please write us.