$2.50 (USA) £1.20 (UK)
Volume 1, Number 2
Mar/Apr 1981
й
eWidget |
Programs: eLife
eTic Tac Toe
"riu! =
eMake Music Boolean Operations Reverse Video
6 Book Reviews
$
Searle:
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XA
* AS А 25, c
What's Coming
Speed Up Screen Displays
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CAI INSTRUMENTS Introduces the WIDGET" Series of Peripherals for the ZX80
open the door to real computing. "WIDGET" $49.95 | 'WIDGET^$99.95 Widgiprint
The Widget interface board allows your Тре Widgiprinter is а 28 column thermo ZX80 to communicate with the rest of the printer that provides a hard copy of world through both a serial RS/232 data results Нога your programs at a price you bank and a parallel TTL input and can afford.
output parts.
а : Have you developed a unique option or g 3 (8) WIDGET” $99.95 Widgitape application tor your ZX80? We at CAI The Widgitape is a revolutionary tape would be interested in discussing the storage system that provides the features possibility of marketing your idea for you.
of high priced floppy disks at a fraction Contact us. of the cost.
Unit Price
Remember this new “WIDGET” Series can open the door to real computing for your ZX80.
Send Check, Money Order, or Credit Card WIDGET тыға КЛИН Company to: WIDGIPRINT тек MM WIDGITAPE
. TOTAL e 6 CAI Instruments, Inc. Card No. Visa 5 2559 Arbutus Court Mastercharge o Е Midland, MI 48640 Exp. Date g Name Address City . * Зв ZIP
Or order by phone (517) 835-6145 giving your credit
said number. Michigan residents add 4% sales tax
The magazine for Sinclair ZX80 users
— ўс
March/April 1981
Volume 1, Number 2
36 40
10
16
ARTICLES & INTERVIEWS
Growth Plans and Pains................... АН! & Searle An interview with Nigel Searle
Letters to the ЕдНог.......................... Headers Corrections and tips
Interview With Alfred Milgram. ..........Ah/& Milgram The president of Melbourne House speaks out
Crash Сигвог.................................. Truman The saga continues
The Home Computer Market.................... Searle Crystal ball gazing
Puzzles & РгоМетве........................ Townsend
HARDWARE TIPS
Micro ӉУшсе.................................... Капїег Overcoming power line surges
Using the MicroAce with Sinclair Accessories. ......... Changes you can make to the PC board
Video Modifications for the ZX80...................... Reverse video and direct video
PROGRAMMING TECHNIQUES
A Display F ile in Machine Соде................. Logan Speed up your screen displays
Memory Display................ TERR Cromley Look into the memory of your ZX80
18.
20
47 48
Truth in Programming. .......................... Lubar How to use Boolean operations
Data Statement Simulation..................... Turner Your ZX80 can look like it has Data statements
PROGRAMS & SOFTWARE
Үуіддеі....................................... McGath Simulation of a manufacturing company
АгїШ!егу.................................... Whetstone Hit the target with your ZX80 cannon
Game оҒІйе...................................... Ahl John Conway's classic game
Тіс Тас то... „о. авзон анана кекен Hoffman Noughts and Crosses if you prefer
Making Music With the ZX80................... Forsen Second best thing to a music synthesizer
REVIEWS & EVALUATIONS
ZX80 Рговагатв.................................. Stein ZX80 Pocket Воок............................... Stein ZX80 Magic Воок............................... Stein Active Display and Breakout.................... Sutton ZX80 Сотрапіоп................................ Stein Disassembled Basic............................. Lubar
NEW PRODUCTS & RESOURCES
Product Ргеміем................................. Staff
Вевоигсвв....................................... Staff .
Publisher/ Editor-in-Chief Editorial Director Managing Editor
Staff
Advertiser
David H. Ahl George Blank Paul Grosiean
CAI Instruments
Basic Computer Games
Computer Music Record
Index to Advertisers
Associate Editor David Lubar Creative Computing
Secretary Elizabeth Magin Creative Computing Press Production Manager Laura MacKenzie Creative Computing Back Issues Typesetter Jean Ann Vokoun Lamo-Lem
Financial Coordinator William L. Baumann Linsac
Bookkeeper Patricia Kennelly LJH Enterprises
Customer Service Patricia Brown K. MacDonald
Order Processing Joan Swihart Melbourne House
Circulation Suzanne Guppy MicroAce
Frances Miskovich Dorothy Staples Peripherals Plus Phipps Associates
Rose Cassettes Sinclair Research SYNC
SYNC T-Shirt
March/April 1981
Outbound Engineering
Volume 1, Number 2
Page 31 SYNC is published bi-monthly for $10.00 per year Cover 2 by Creative Computing, 39 E. Hanover Ave., Mor- 21 rs Plains, NJ 07950. Controlled Circulation Cover 3 pending at Allentown, PA. 41 17 Postmaster: Send address changes to SYNC, P.O. 17 Box 789-M, Morristown, NJ 07960. 21 21 Subscriptions in USA: 6 issues $10; 12 issues $18; 23 18 issues $24. UK and foreign airmail subscrip- 7 tions: 6issues £10; 12issues £18; 181ssues £25. Call 11 (800) 631-8112 toll-free (in NJ, 201-540-0445) to 23 begin your subscription. 39 19 Copyright 1981 by Creative Computing. АП rights 23 reserved. Reproduction prohibited in any form. 3 33, Cover 4 15
Growth Plans and Pains An Interview with Nigel Searle
Nigel Searle is Sinclair's man in Boston. He is responsible for operations in the United States and Canada of Sinclair Research Ltd.
Recently Mr. Searle visited Creative Computing and spoke with publisher David Ahl, about the future plans for the American operations of Sinclair.
N.S.: Asageneral plan I would like to see us explore one new market every six month period. I think that in four or five months just about anybody who is thinking about buying a personal computer (which is to say the reasonably technically oriented people, the same sort of people who have already bought computers) must be aware that there is an option of only spending a couple hundred dollars to get started. Market awareness is very high.
By the middle of 1981 I would like to achieve a similar level of awareness among people who make either purchasing deci- sion or recommendations regarding com- puters to be used in schools. Simultaneously, we will focus our own mail-order efforts on the home educational aspects of com- puters in an attempt to reach beyond the technical audience. Any parent who is thinking of buying a computer for his children will know that there is a low-cost entry point, and will not have heard only of Apple and TRS-80.
2
Itissurprising how many teachers there are who read only educational publications. Even though they may teach math or computing, they don't read the computer publications. At this point these teachers are totally unaware of the fact that there is such a thing as the ZX-80, and will remain ignorant unless we do something about that by addressing them through the appro- priate channels.
My target for the first half of 1981 is to achieve a level of awareness in the educa- tional market. We would like to find a single distributor who is capable of handling this market with relatively little support from us other than the product. We would share all the knowledge we have gained from our experience in other markets, but we are hoping to achieve a rate of growth that will be just about impossible to do on our own.
The negotiations that we are having at the moment don't look overly promising and I don't want to suggest that anything is going to happen soon. I believe that traditional publishing companies would make the best kind of partners for the educational market because of they are already selling to schools. They have the sales force to do the job. They have the ability to produce and publish the collateral material, software etc. And like most publishers they realize that their future lies not only in ink and paper. The problem
is that their sales force is not necessarily experienced in selling hardware. But you must compromise somewhere.
D.A.: What arrangements do you have with Image Software?
N.S.: What we are selling there is our computer plus Image Computer Products' Computer Learning Lab as a single package. Our ads in the non-technical publications next year are going to go very strongly on this theme: selling the benefit of in-home education, rather than selling the product itself as we do now to the technical audience.
It does no good to tell someone who does not know what a computer is, that he needs a computer. You’ve got to tell him what it will do for him. Then he will understand. If you are advertising in Popular Electronics, the readers already know what a computer can do for them; they want to know what this particular product is. But for the wider, non-technical market you have to detail the benefits. I think that ina year most of our mail-order ads, for what- ever market—technical or nontechnical— aren't going to look very much like ads for hardware. They will look like ads for soft- ware, because all the emphasis will be on applications.
D.A.: That's where we are now with our magazine positioning: it's applications and software. We think that eventually there is a much bigger market for that than for
SYNC Magazine
Learn how touse a computer
for $249. And keepthe computer.
Introducing the Computer Learning Lab, with the Sinclair ZX80 personal computer.
The Sinclair ZX80 is a powerful, personal computer already in use in tens of thousands of homes and busi- nesses.
Now, for just $249“, the Computer Learning Lab will teach you and your children how to use this complete, ex- pne computer right in your own
ome. And when you're done, you get to keep the computer!
The Computer Learning Lab is a self-paced course that teaches the ins and outs of computers. It cuts away jargon and mystique, taking you straight into BASIC—the most com- mon, easy-to-use computer language. And the computer itself does the teaching.
100 LESSONS MAKE LEARNING EASY.
You just take the ZX80 out of the box, connect it to your TV and an or- dinary cassette recorder (connectors are provided), and slip in the pre-pro- S s de Learning Lab cassettes.
here's nothing extra to purchase.
You'll be wor ing with the computer your very first day!
The cassettes take you through 100
ets о & Sem “Se
To order call toll free: 800-543-3000. In Ohio call: 800-582-1364. Ask for operator #508. Phones open 24 hours a day,
7 days a week.
se ре Гы that teach you how to solve problems with the ZX80.
You learn by doing. By actually working with the computer.
And the lessons are designed to be fun and involving. You create your own programs for games, code breaking, interest calculation, and other topics. Then you can apply the principles youve learned to more complex problems.
In fact, you'll be a master of the ZX80. To use in your business, for home budgeting, or just for fun.
We'll also send you a catalog full of ready-to-use programs- from Loan Amortization to Lunar Lander—avail- able for as little as $6.95.
THE ADVANCED DESIGN OF THE ZX80.
The ZX80 is the world’s first truly portable computer. It features a touch- sensitive keyboard and a 32-character by 24-line display.
And it performs like a much larger and more expensive computer. Single keystroke entries make typing pro- grams fast and easy. An automatic error detection feature tells you if you
The complete package
includes the ZX80, a 128-page guide to computing, a workbook, six program cassettes, and two blank cassettes for storing
your own programs.
Please send me — Lab(s) with the ZX80 personal computer at $2 each (U.S. dollars).
I enclose check/money order payable to Sinclair Research Ltd. for S
Name
Address
бе
Occupation Intended use of ZX80: Have you ever used a computer? 0 Yes О No
make mistakes. And program editing helps you correct them. Yet the com- plete Computer Learning Lab, includ- ing computer, is still several hundred
Bos 77
The Computer Learning Lab is a family learning aid. Children 10 and above will quickly understand the principles of computing—and have Jun learning.
dollars less expensive than any com- parable computer alone.
The ZX80 is backed by a 30-day money-back guarantee and a 90-day limited warranty with a national ser- vice-by-mail facility. Extended service contracts for the ZX80 are available for a minimal charge.
To: SINCLAIR RESEARCH LTD., ONE SINCLAIR PLAZA, NASHUA, NH 03061. Computer Leang
Please send me _______. ZX80 computer(s) only, without the Learning Lab, at $199.95* each.
(Add $5.00 for shipping.)
*For Conn. deliveries, add sales tax.
Zip Age
Do you own another personal computer? (1 Yes Ч No
Searle Interview, continued...
the hardware oriented magazine.
From a competitive standpoint, what
do you think the impact will be of the new Commodore VIC: a four-color, 5K memory computer with lots of capability for only $300? N.S.: It is obviously a much keener competitor than anything that exists at the present time. But we're not going to stand still. One of the amazing things to me is that we have sold as many computers as we have, when all we offer is Integer Basic and 1K bytes of RAM. Within a few months, I hope we will have the 16K RAM and the 8K Basic, which will greatly expand our market.
We feel that we are in a strong position to respond to competition. If Commodore were talking about a $200 price point for the VIC, then I would be more worried than I am. I think they will offer more competition than anyone else in the market at the moment. But I don't think we are going to have much difficulty in saying, "Here's our machine. Here's Commodore’s. Look at the difference in price and look at the difference in functions, and about the only thing extra you get from Commodore is color."
D.A.: What about some of the newer Japanese entries? Are there any on the horizon that look like competition?
N.S.: The amazing thing to me, again, is that I don't see any signs from anyone other than Commodore that they are interested in the really low end of the business. I don't know why Commodore is the only company that has shown interest. Perhaps this is because it hasn't, in general, been doing very well here in the states. Therefore it has nothing to lose; it's not
going to lose high-end sales by selling a` `
low-end machine.
We have proved that a market exists. Our sales are sufficiently high that we have discussed an advertising strategy calling ourselves “The World's Number 1 In Personal Computers." This means that Sinclair has sold more personal computers than any other company —even when you include the models of all the other com- panies. Frankly, I am not in any hurry to make that claim, nor is Clive Sinclair. We kind of like the fact that nobody else yet seems convinced that a big market exists. The longer they remain unconvinced, the better I like it.
D.A.: You mentioned the 16K memory and 8K Basic. Are they two separate plug- ins?
N.S.: The 8K Basic is a single chip which takes the place of the 4K chip on the main board. You simply remove the cover, take out the 4K chip and plug-in the 8K chip. The 16K memory module plugs in to the connector on the back of the board. It is in a small case about 2 1/2” square.
D.A.: Do you have any projected prices on those two?
4
N.S.: The 16K RAM will be $99.95. The 8K Basic almost certainly will be $39.95. D.A.: I know no one likes to talk about pricing, because you never know where things will end up, but if competition heats up substantially, would you meet it with price or with something else?
N.S.: I don’t mind talking about it. We buy our components from the same people that everyone else does. If you are engaged in a price war, then you have to be very smart in your design, and you have to be smart in your buying. You've also got to be very careful that you don’t build at yesterday's prices and sell at tomorrow’s prices. I hope that we at Sinclair have learned something from being in the calculator business and that we will be better equipped to cope with that sort of downward spiral of prices if it turns out that way.
I am probably more pessimistic about that happening than are most people in the business. I don’t think the personal computer, once it becomes a truly consu- mer-oriented item, is going to be very different from the calculator in terms of its marketing. Features will count for almost nothing except at the initial stage. All that anyone will care about is that they get the cheapest computer. Because they are dead scared that they will buy one for $50 and tomorrow a friend will buy one for $35 and they will feel like an idiot. That is all that motivated the drive in calculator prices down to $29.95 and then $19.95.
There eventually emerges a price that people are willing to pay and they want the best you can give them at that price. If they can get everything they want then they don’t want to pay more than that critical price. I think we are well equipped to buy components to design the product using our experience with the calculator business. I think we are well equipped to survive that kind of price war and, hopefully, we are smart enough to look ahead to see what kind of product we will need afterward to compete with the Japanese —if indeed itis the Japanese who come along afterward as they did in the calculator business.
The other thing about the calculator business that may be true for the computer business is that there came a time at various stages in the calculator business where you couldn't sell a calculator unless it was of a particular type. I have said that people weren't feature conscious, but they were in a very unselective, media-directed way. There were articles about how to buy a calculator — they would say “4о not buy а calculator with disposable batteries, it must have an A/C adaptr and recharger." That remained true for quite a long time until Rockwell brought out the first calculator that ran off a single nine-volt battery. It was far superior to a rechargable battery system.
But because people were told not to buy a throw away battery system because "they will run down in no time at all and
will cost you a fortune" people still believed that to be true even when they had a single nine-volt battery unit available to them. Then there was a time you couldn't sell a calculator unless it had a percentage key, or a memory key on it. Despite the fact that of all the people who bought calculators with a memory key only 2.576 used them, no one would buy one that didn't have a percentage key; they read in Consumer Reports that you should have one.
Itis dangerous to say that the computer business is going to be just like the calculator business. It will be different, and it is probably pointless to make comparisons with other products and other markets. It is, however, going to be more like the calculator business than people think.
D.A.: I feel that in the market for the low- end computer — not just the Sinclair, but the VIC, Mattell, APF etc.—a big mistake is being made in trying to initially sell the
broad consumer market. The best market
for these products is made up of people who already have a computer— those who have bought an Apple, Altair etc. — and don't want their kids playing with it all the time. Or they want a state-of-the-art unit
for themselves. | N.S.: Absolutely. In a sampling of thd
people who bought our computer from an ad in Popular Electronics, 38% already owned a personal computer. But, obviously, in the long run we do not want to sell exclusively to people who already own a personal computer, because then we can only sell as many units as all other manufac- turers put together.
D.A.: My pointis that I believe a computer is still a new enough device that someone buying it wants a recommendation from
someone else who has one. N.S.: Perhaps. But there may be another
way. You can't convince a large part of the market until they have actually used the machine. Our consumer market adver- tising within the next couple of months will start to go on the attack. Rather than hide our free trial offer, money-back guarantee in the fine print, we will put it right up front. So much up front that it might well be the headline. We've been kicking around ideas at the advertising agency with lines such as "You can't try the Sinclair for 10 minutes in any store, but you can try it for 10 days in your own home at no cost." Just using the old fashioned mail-order ploy that says "Please, please, take one and try it. If you don't like it send it back. But please try it.” We think that trying it will convince the customer to buy it. []
SYNC Magazine
Lect
Our Face is Red!
Dear Editor:
I recently received my first copy of Sync magazine and I was very pleased. However, I would like to point out a few things I found wrong.
1. Page 18— Nicomacus — Line 100 should read 70*a t- 21*b + 15*с. As listed, this pro- gram correctly deduces numbers only from 7 to 104 or between 6 and 105.
2. Page 35— Multiplication Tables— Line 330 needs a semi-colon after A$ to run properly. Line 335 should have a comma instead of a period in the beginning of the print message.
3. Some of the listings require the use of spaces or changes in the print format in order for the messages to print out properly on the tv screen. Also, it would be a good idea to let your readers know if a listing will run in 1К memory. Some of your programs occupy so much memory, they will not run. For example; Page 36 — Basic Accounting — As listed I could only enter up to line 2055 before I ran out of memory.
To be sure, the above items are only minor in nature, but I would appreciate hearing from you. All in all, I find the magazine to be an excellent one which I shall continue to subscribe to. Thank You.
John A. Sampson College Point, NY
March/April 1981
Four Tips for MicroAce Owners
Dear Editor:
These suggestions are based on my experi- ence with the MicroAce.
1. Lacquer thinner and an old toothbrush are useful for cleaning solder flux from the PC board.
2. Changing R24 from 1K to 4.7K increases the sensitivity of the cassette input but still holds pin 2 of U11 close enough to ground for an adequate noise margin.
3. The crystal oscillator did not always start, especially when the computer was first plugged in. This problem was eliminated by a 100K resistor from pin 12 of U18 to ground (across C8). This is a leakage resistor which apparently draws off an accumulating charge on pin 12.
4. The keyboard input IC (U11) blew twice from a static charge while I was using the computer on a carpeted floor. This 7415365 is replaceable by а 7415367, which Radio Shack carries.
David A. Cromely
Channel 2 Interference Problem Cure
Dear Editor:
Enclosed is my check for a one year subscription to your SYNC magazine. Hope it is as good as your brochure states.
There are two items I'd like to relate about my experience with my ZX80. First, as you know, the computer is tuned to operate on Channel 2. Here in Atlanta, I live close to the station, and I could not display on this channel without a very objectionable amount of interference. I hoped there was some way to cure the problem, so I called the "technical rep" at Sinclair. His solution was-use the computer in the basement-find a room with metal all around-or move. Some help! Some old timers at work recommended I try inserting iron or brass in the tuning coil. By this time I had very carefully removed the cover from the non-adjustable tuner. Although the iron and brass did affect the frequency, it was not enough. A second idea was to very gently spread a few of the windings of the coil. Praise the Lord! It worked like a charm. I was able to to tune it to Chan. 3 with no problem at all. I closed up the unit and Гуе been on a good clear screen ever since. The second item concerned the cassette recorder. I set the controls, etc. just like the manual said. About 50% of the time I could not load from the cassette recorder to the computer. That is, until I tried the volume control setting at less than the maximum as recom- mended in the manual. In my case I can leave the setting on 7 and save and load with virtually no failures.
Well, thats it. Hope this info saves someone the frustrations I went through.
R.E. Henneberg
An Interview with Alfred Milgram
D.A.: Nigel Searle made an interesting comment about marketing kits by mail order. He said that kit builders in the U.K. generally knew what they were doing and there was very little trouble or returns. whereas in the U.S. it is entirely different. People buy a kit expecting it to be like a leathercraft or model car kit that any kid can assemble. Nigel told me of a person who called after buying a kit and asked, “What’s a soldering iron?" In the U.S., MicroAce sells a version of the ZX80. While there's not a lot of soldering or assembly to do, people have to know or do have to handle the integrated circuits reasonably carefully. Static electricity is a real enemy, at least until the chip is installed. They also have to know that you can't use the same sort of soldering gun that you use for your plumbing repairs to solder a printed circuit board.
A.M.: How is MicroAce distributing their product here? I don't see them in the magazines, they are not visible.
D.A..: Strictly by mail order. They have been restricted by Sinclair from advertising in a certain group of publications that Sinclair has reserved for itself. Sinclair has more or less picked the top one or two magazines in each individual field and left the balance to MicroAce which is a policy. in my mind, to defeat MicroAce. What is the story on that? What actually happened between Sinclair and MicroAce?
A.M.: The people at CompShop have a history of copying. The guy behind Micro- Ace is the guy who runs CompShop in the U.K. Atone stage they couldn't get enough supplies from Ohio Scientific, so they redesigned the OSI Superboard and got the ROM from Microsoft. Now they are paying the royalties to Microsoft, have redesigned the board and are selling it as the U.K. 101.
Then the Sinclair came out and they figured here was a golden opportunity to save on development costs and come out with effectively the same machine. They copied the ROM, byte for byte, moved the circuits about, cleaned it up a bit, and moved the RAM memory away from the heat sink. The case is black instead of white, and they were going to market it in
6
the U.K. for £ 50 as opposed to £ 770, the price of the ZX80. Sinclair got upset and sued them for breach of copyright. In the case two items were put up for breach of copyright: stealing the ROM and the keyboard. The judge said in effect, "I can't read the ROM. Nobody can read the ROM. The ROM is not copyrightable. But the keyboard: that's the same keyboard, anyone can see that." They settled out of court. D.A.: SoSinclair then licensed them to do a kit version?
A.M.: They allowed them, because at that stage they had gone quite a ways into manufacturing, and were already com- mitted, with many thousand ROMs and printed circuit boards and all the rest of it. They couldn't afford to pull out of it at that stage. So Sinclair allowed them to market it as long as they didn't sell it in the U.K.. only sold it in kit form, and complied with the restrictions on advertising. D.A.: From what I gather there are people at Sinclair that would like to design periph- erals and add-ons that specifically would not fit the MicroAce.
A.M.: One of the reasons they told me that they were not prepared to let the new ROM out, was that they did not want to be ripped-off in the same way. I don't think they can really avoid it in the long run. Because basically anyone who has a Micro- Ace can go and buy a new ROM from Sinclair and pop it in.
D.A.: Will it fit?
A.M.: Yes, because it is a straight copy. The only thing that MicroAce has done is to add another 1K on board. Apart from that it is exactly the same machine. It has the same routines which all run in the same places, the same operating system, the same number of chips, it is basically the same machine. I can't see how Sinclair can design anything that would not be compatible with the MicroAce.
D.A.: Tell me a little more about your plans. You mentioned two books, one on machine language programming.
A.M.: We've done exceptionally well in the U.K. with our first book, 30 Programs For the ZX-80, because it seems that the
market is mainly people who have not bought a computer before and they don't
know what to do with the machine. We are finding that a lot of buyers are people who don't even know how to enter a program. They are are just following blind, letter for letter. But the cost of the machine, in our mind, made it so it wasn't worth marketing cassettes in the U.K. There are a lot of people who are marketing cassettes in the U.K. but they tend to have six or eight programs on one cassette.
There is a subgroup of users who are very interested in going further, and using the machine as a learning tool in developing their own programs. It is for those people that we are doing machine language pro- gramming and programming techniques. Programming Techniques is fairly basic. It uses the specific capabilities of the Sinclair. You could just buy a book on Basic programming. but the language isn't quite the same because you are working with a subset. So you must know how to cope with certain limitations —not having a step function in loop. for example. The biggest difference is the totally dynamic display screen where the display shrinks and expands as you use the machine. So you just can't poke in and out of the screen or easily move things about. Then there are the people who want to use machine language programming for its user sub- routine capabilities. But again you need special advice beacause there is no RAM protected area.
There are ways of entering machine programs and yet being able to save them, because when you save a program on cassette you can save all the variables as well. So you can retain a machine languge program on tape and use it later.
D.A.: How do you save machine languge programs?
A.M.: In our 30 Programs book. several programs utilize machine language routines. We show two different ways of loading those routines into the program. The two simplest ways are to load it into a REM statement or to load it into a variable. D.A.: Into a Remark statement? A machine language routine? How can it then be used?
A.M.: You make your Remark statement the first statement of the program. So you
SYNC Magazine
Interview, continued...
know its location. You poke the values into the Remark statement later on. Then, because you know absolutely its location, you can call up the subroutine. If you use a variable to poke it into, you have to remember that the computer is dynamic and every time you call a new variable it's likely to shift in position. So you have to peek into the location which tells you where the variable storage starts.
D.A.: We received one article, in which someone showed how different characters-— graphic characters—could be put on the screen to create a moving graphics display. It emphasized that you had to peek to the beginning or look at the beginning of the graphics display in the same statement that you poke because of the dynamic allocation.
A.M.: That’s true unless you have defined all of your variables first. However, you must remember that loop variables have a separate definition from your regular vari- ables (because they are stored differently in the machine).
D.A.: Do you think that the 8K Basic will be any more standard?
A.M.: Itisastep closer. It has step functions available, trigonometry and other scientific functions, decimal numbers, and string arrays. All of those things mean that the subset is that much closer to Microsoft Basic. What you don't have is the ability to define variables and integers, which I think
"This Book is Excellent!"
— Clive Sinclair
is very stupid, because you are wasting a lot of memory when you are just using ordinary integer arithmetic.
D.A.: Where do you see Sinclair going in two or three years? Do you see prices coming down, etc?
A.M.: I think Clive Sinclair is going to move out of the computer market. I think that what he should be doing is moving into the small businessman's cheap com- puter. Because he has a reputation in the U.K. of being able to come out with a product which is technically brillant, but very cheap and very tinny. That's what he does, and he does it very well. If he came out with a computer for £300 which would be very basic —a 16K machine with a one- page word processor, that could handle invoicing for 30 accounts or whatever you can get into 16K, and a very cheap printer for - 200, it would sell an immense number of small business machines. But I don’t think he sees it this way. I think he is going to move out into other markets.
Sinclair is the first in the personal computer field who has come out with such a low price. But very soon there are going to be others who are going to offer better products for the same price. And he won't be able to compete any more. He has been able to do well because he was first. And he has shown the potential that exists both in terms of technology and in terms of marketing. Just as he wasn’t able to keep up in electronic watches or pocket calculators, I don’t think he will be able to
keep up in the computer field.
D.A.: Word reaches us that the next big thing that Sinclair is working on is “flat screen television.”
A.M.: He has been working on that for years and I think that he probably will do 1t
D.A.: They claim that the flat screen television is being built and sets will be on the market by this December.
A.M.: I will be surprised if it is that early, because he has always had a problem with delivery. He will probably demonstrate a model by December.
D.A.: Isyour machine language program- ming book going to take people by the hand assuming they don't know anything about programming at all.
A.M.: The people who are involved in the 7,Х-80 users club in the U.K.—and they know the Basic very well — still don't know how the user function works. They don't understand how you get a machine language program to run. If that is at all typical, and I think that it is, then the people who have now taught themselves some Basic want something different. They bought the computer because they think it is time to learn about computers, and they don't understand the way the machine language іп the computer works. The ZX-80 machine | language code is a very powerful one but | it is also very complex. It is a very useful code; you can do a lot of things with it. Our book will try to put it within the grasp of every reader. Г
The unique book contains 30 programs all designed to fit in the basic 1K version of the SINCLAIR ZX80!!
With this book you will realise that the ZX80 is more powerful than you ever imagined! 112 pages packed full of solid information!
BLACKJACK — actually contains a full pack of cards, shuffles them, keeps track of the dealer and player totals, and the money bets, all within 1K.
Dr. Tn — a truly conversational program: DR. ZX-80 is your personal computer analyst.
LINE RENUMBER - an invaluable program which automatically renumbers lines and puts order to your programs.
MEMORY LEFT — an incredible routine especially useful with only 1K, which lets you know to the byte how much memory is left. This also illustrates USR routines. GOMOKU — the computer challenges you to this complex Japanese game, incredibly this program including display of the 7 x7 board fits into 1K — it only does so because it uses the display as memory!
Other programs included are HORSE RACE, LUNAR LANDER (with moving spaceship display, NOUGHTS AND CROSSES, NIM, SIMPLE SIMON, HANGMAN, LIFE: MASTERMIND, PINCH and 16 others!
available $ 1 4 95 Other Шалды > include:
by mail (plus ни ZX80 Machine Language
order only and handling) Programming
MELBOURNE HOUSE Orders to: IMAGE COMPUTER PRODUCTS PUBLISHERS 615 Academy Drive, Northbrook, III. 60062.
Please send me copy/ies of '30 Programs for the ZX-80: 1K
Please encolse Check or Money Order NAME for $15.95
ADDRESS
March/April 1981 7
(ff
^
Owners of the Sinclair ZX80 and Micro- Ace rapidly discover that interruptions of power can cause headaches, not to mention the necessity for re-keying programs. If you live in the "Sunshine" state. Florida, you also have to contend with “Florida- Flicker & Flash,” better known as the local utility company. They achieved their reputation by the repeated switching between feeder lines, causing lights to flicker, creating all sorts of problems for computer users.
After re-keying several programs into my MicroAce, the Micro-Juice project was born. Most major computer installations use large and expensive line conditioning transformers, filters, and if the area or data is important enough, a device called a U.P.S. The uninterruptable power supply is illustrated in a simple block diagram (figure 1), and generally consists of a device to convert direct current from a storage battery to alternating current, with a switchover network to allow it to take over if commercial power fails. There are several variations on this basic circuit, but generaliy the U.P.S. allows operation for up to one hour, depending on current requirements, and the size of your budget. This protection doesn’t come cheaply, because U.P.S. systems start at over two hundred dollars.
It makes little sense to spend two-hundred or more dollars for a ZX80 U.P.S., but Micro-Juice serves the purpose for about $10. Fortunately, the ZX80 and the Micro- Ace were well designed for this addition. Tests on my MicroAce showed that the unit drew approximately 330 mA in use,
and the d.c. input from the power supply
Elliott S. Kanter, 1704 Raleigh Ave., Holly Hill, FL 32017.
Elliott S. Kanter |
was about 14 Volts unloaded, with the on- board five volt regulator handling the transition to the five volts the ZX80 needs.
All we wanted to do was to insure that the computer and its memory would remain powered during a power flicker or loss. To do this we needed a source of d.c. some- where between 5 and 15 volts, supplying 330 mA for about an hour. The transition would have to be so quick as to not disturb the memory. Another requirement was that the Micro-Juicer had to be easy to build and duplicate, using easily obtained parts, and represent as good a value as the computer itself. Considering all those requirements, I was both pleased and surprised to be able to come up a circuit meeting all these needs.
Examining the circuit in figure two, we see that Micro-Juice is somewhat similar to the block-diagramed U.P.S. system. Both sense a drop of commercial power and immediately apply an alternate power source. Micro-Juice, however is simpler and costs less, relying on 9 volt alkaline batteries, which provide power for over an hour.
The circuit is mounted in any convenient box, offering the builder the option of bypassing the two input jacks, and simply cutting the power cable from the wall- supply, feeding it directly into the cabinet. If you use this approach, make use of strain relief grommets and take careful note of polarity — the tip is positive, and the ring is negative.
After assembling the circuit and checking both the polarity of the connections for input and ouput power, and the orientation of the diodes, connect Micro-Juice to your ZX80. With the normal a.c. system in operation the cursor will be visible. When
SYNC Magazine
INVERTER WITH BATTERY CHARGER
POWER OUT
BATTERY SUPPLY
Figure 1. Block Diagram, U.P.S.
Parts List 274-251 — Л, J2 two conductor, open
you pull the power supply from the wall outlet the ‘K‘ remains.
Micro-Juice is not a portable d.c. supply capable of running the ZX80 indefinitely, but it is a fail safe device to guard your program from accidental power interrup- tions. Another convenience of this system is that all required parts are available at your local Radio Shack. The parts numbers are listed below. О
POWER IN
d
B1,B2
CONNECT IN
PARALLEL
Figure 2 — Micro-Juice
circuit 1/8 inch phone jacks.
274-286 — P1, P2 two conducter, 1/8 inch phone plugs.
276-1101 — D1, D2 diodes, at least 50РТУ 1А.
23-553 — ВІ, B2 or equivilant 9 volt akaline batteries.
270-233 — Cabinet, 5 1/6 X 25/8 X 1 5/8 inches.
Solder
Assorted wire
NEGATIVE м POSITIVE [Рт р2 0 ==
March/April 1981
Using the Microace with Sinclair Accessories
1 — Repair cuts shown & remove links presently installed. 2— Cut tracks where shown.
3— Make link between A & B.
4— Make link between X & Y.
Solder Side
To illustrate modifications required to run new 8К ROM chip
Cut the 2 traces shown here
© о H oc Repair "y “т.
жы TIR — SI 7 1 ps
00000000
0000000
The 16K RAM Module: 7 1
The 16K RAM Module is completely жн both links and repair the cuts that we have
compatible with the MicroAce ІК Kit; __ made using a small piece of wire. (see
the unit can be simply plugged on the y above).
back. If the RAM Module is to be fitted to The next stage is to cut the track that goes
a 2K Kit then the extra 1K should be to pin 13 of the ROM chip and the track
removed along with U17. Please be sure == that goes to pin 14 of the ROM chip as
that the 2K2 resistor has been installed in shown above
place of R16. The Module may now Бе ™ Now use a small piece of wire to make a
plugged onto the back of the machine. m link between pin 13 of the ROM chip (on е the PCB) and pin 18 of U6.
The 8K Basic ROM: » Also make a link using another piece of
The MicroAce kit comes with two track wire between pin 14 of the ROM chip (on
cuts on board, i.e. both sides of pin 21 of the PCB) and pin 3 of U6.
the ROM chip. You also need to make The new ROM chip may now be plugged
two links on the board. into its socket and power applied to the
Before installing the new ROM chip, remove board.
10 SYNC Magazine
EEE
The unique and valuable x components of the MicroAce
The MicroAce is not just another personal computer. Quite apart from its exceptionally low price, the MicroAce has two uniquely advanced components: the powerful BASIC interpreter, and the simple teach yourself BASIC manual. The unique versatile BASIC interpreter offers remarkable programming advantages: € Unique 'one-touch' key word entry: the MicroAce eliminates a great deal of tiresome typing. Key words (RUN, PRINT, LIST, etc.) have their own single-key entry.
€ Unique syntax check. Only lines with correct syntax are accepted into programs. A cursor identifies errors immediately. This prevents entry of long and complicated programs with faults only discovered when you try to run them.
€ Excellent string-handling capability — takes up
to 26 string variables of any length. All strings
can undergo all relational tests (e.g.
comparison). The MicroAce also has string
input — to request a line of text when
necessary. Strings do not need to be
dimensioned.
Up to 26 single dimension arrays.
FOR/NEXT loops nested up 26.
Variable names of any length.
BASIC language also handles full Boolean
arithmetic, conditional expressions, etc.
€ Exceptionally powerful edit facilities, allows modification of existing program lines.
€ Randomise function, useful for games and secret codes, as well as тоге serious applications
€ Timer under program control.
А Micr
The [Місгобсе]
€ РЕЕК and POKE enable entry of machine code instructions, USR causes jump to a user's machine language sub-routine.
€ High-resolution graphics with 22 standard graphic symbols.
€ All characters printable т program control.
€ Lines of unlimited length.
reverse under
‘Excellent value’ indeed!
For just $149.00 (excluding handling charge) you get everything you need to build a personal computer at home... PCB, with IC sockets for all ICs; case; leads for direct connection to a cassette recorder and television (black and white or color); everything!
Yet the MicroAce really is a complete, powerful, full-facility computer, matching or surpassing other personal computers at several times the price.
The MicroAce is programmed in BASIC, and you can use it to do quite literally anything, from playing chess to managing a business.
The MicroAce is pleasantly straightforward to assemble, using a fine-tipped soldering iron. It immediately proves what a good job you've done: connect it to your TV ... link it to the mains adaptor ... and you're ready to go.
Fewer chips, compact design, volume production-more power per Dollar!
The MicroAce owes its remarkable low price to its remarkable design: the whole system is packed on to fewer, newer, more powerful and advanced LSI chips. A single SUPER ROM, for instance, contains the BASIC interpreter, the character set, operating system, and monitor. And the MicroAce 1K byte
Licenced by Sinclair Research Ltd.
ocompu for everyone at
- a new generation of
miniature computers
A COMPLETE COMPUTER
for $149.00 for 1K Kit Post and Packing FREE (Add 696 Tax for Shipments inside California)
RAM (expandable to 2K on board) is roughly equivalent to 4K bytes in a conventional computer — typically storing 100 lines of BASIC. (Key words occupy only a single byte.)
The display shows 32 characters by 24 lines.
And Benchmark tests show that the MicroAce is faster than all other personal computers.
No other personal computer offers this unique combination of high capability and low price.
The MicroAce teach-yourself BASIC manual.
If the features of the BASIC interpreter mean little to you-don't worry. They're all explained in the specially-written book free with every kit! The book makes learning easy, exciting and enjoyable, and represents а complete course in BASIC programming-from first principles to complex programs. (Available separately-purchase price refunded if you buy a MicroAce later.)
A hardware manual is also included with every kit.
The MicroAce Kit: $149.00 with IK COMPLETE $169.00 with 2K
Demand for the MicroAce is very high: use the coupon to order today for the earliest possible delivery. All orders will be despatched in strict rotation. If you are unsuccessful in constructing your kit, we will repair it for a fee of $20.00, post and packing FREE. Of course, you may return your MicroAce as received within 14 days for a full refund. We want you to be satisfied beyond all doubt — and we have no doubt that you will be.
Sockets for TV, cassette
Z80 A microprocessor chip, widely recognised
as the best ever made. recorder, contains... UH Е power А Ехрапѕіоп supply. Connector TV SUPER modulator ROM. L
Rugged, RAM flush Clock. chips ush,
Keyboard
Your MicroAce kit
Printed circuit board, with IC sockets for all ICs. Complete components set, including all ICs-all manufactured by selected world-leading suppliers. € New rugged keyboard, touch-sensitive, wipe-clean. € Ready-moulded case.
H Quantity € Leads and plugs for NN MicroAce КП Ts. | 9199009 KENNEN H | | MicroAce Kit 2K | $169.0 | | [ С БЕНЕН С О
connection to domestic TV and cassette recorder. (Programs can be SAVEd and LOADed on to a portable cassette recorder.) @ Mains adaptor of 600 mA
at 9VDC nominal 1
Description
Shipments inside California add 696 TAX
unregulated.
€ FREE course in BASIC programming and user manual.
[Еа check, Money Order or quote your Credit Card опо: а аа 8 Send Check, Money Order or quote your Credit Card No. to:
MicroAce 1348 East Edinger, Santa Ana, California, Zip Code 92705. В or phone (714) 547 2526 quoting your Credit Card Number.
Unit Price
1K Upgrade Kit $29.00
TOTAL
JOIN THE REVOLUTION - DON'T GET LEFT
BEHIND - ORDER YOUR MICRO ACE NOW!
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Video Modifications for the ZX80
12
REVERSE VIDEO
It is possible to directly invert the video signal that leaves the ZX80 and drives your TV. This is done by accessing pin 9/1С9, instead of pin 7/IC9, as the input (pin 4) to IC20. Below are the in- structions for the modifications.
Remove the entire case from the ZX80. In the right center section of the back of the PCB you will see an etching that looks like this:
" DIRECT VIDEO Nt n A С It is possible to connect a video moni- tor directly to the ZX80. This is accom- plished by passing the RF modulator and adding a small amount of buffer circuitry. This circuit also reverses the video signal which can be controlled by the RV switch shown earlier. Open the ZX80. Look at the modu-
First, cut the trace between points A and C with a razor blade or exacto knife. Now install the following circuit:
RV switch lator. (See Below.) B A <-------- SPDT Switch T с men
Drill an appropriately sized hole in the case. Mount the switch. Close up the case and power-up the system. You will notice that toggling the switch will cause the
video to invert. Tapping the video lead on R30 (see
Schematic), you should run it through the buffer circuit shown below:
3.3K Vcc
2N2222 or similar Video on R30
68.1. Monitor 2.7K
7513.
SYNC Magazine
Howto Produce a Display File
Using Machine Code.
The ZX80 is supplied with a 4K ROM that contains the Basic interpreter. There- fore the average user will use the PRINT command of the Basic language to produce his pictures on the T.V. screen. However Basic is fairly slow.
For example the following Basic program draws a simple rectangular playing area, that could form part of many games, takes over 2 seconds to RUN.
10 FOR I=1 TO 32 20 PRINT “@”;
30 NEXT I
40 FOR J=1 TO 10 50 PRINT "B;
60 FOR I=1 TO 29 70 PRINT “gy”;
80 NEXT I
90 PRINT "g^
100 NEXT J
110 FOR I=1 TO 32 120 PRINT “№”; 130 NEXT I
(shift A) Top line
(space)
Of course the above program could be rewritten using many little tricks and as a result could be quite fast, but it would probably use a lot of valuable memory.
As machine code routines are very fast it is obviously useful to be able to replace the slow parts of Basic programs with machine code routines.
This article goes through the steps
Dr. LS. Logan, 24 Nurses Lane, Skellingthorpe, Lincoln LN6 OTT England.
March/April 1981
The rows
Bottom line f
How Is It Done ?
Dr. l.S. Logan
involved in producing a Display File under machine code, and will show how the above Basic program can be replaced by a machine code routine called using a statement such as:
20 LET K=USR(16427)
However the structure of the normal display file must be discussed first.
The Display File: In the ZX80 the display file is the part of the RAM which holds the next picture to be shown. A complete picture is made up of 24 lines which can be from 0 to 32 characters in length. The display file has an initial delimiting "118", and another delimiting “118” to mark the end of each line.
When a Basic program is RUN the display file can initially be considered to be empty and as each PRINT statement is interpreted the Display File is filled with the required characters.
For example the display file produced by the Basic program above will have the ollowing structure:
== Ist. Line 2nd. Line
32 shifed A’s
3 m '
The part of the display file after the 12th. Line has been left empty in the diagram to show the place where further PRINT statements would add their characters. However if the Basic program is finished (oris stopped) then the end of program RUN routine will complete the display file by adding to the Display File the number of “11875 as specified in the line counter system variable 16421), and then adding the required E-LINE. The Display File will be complete as it holds the characters that will form 24 lines.
Once the above details have been under- stood, then it follows that the machine code routine below must result in a Display
File of exactly the same structure.
An Outline Flow Diagram: There are three parts to any machine code routine construct- ing a Display File. These are shown in the diagram below, and each part will discussed in turn.
3rd.—11th. Lines
As 1st.Line
30 spaces
12th. Line —» _
PICK UP DISPLAY FILE POINTER
CONSTRUCT
PICTURE
RESET SYSTEM VARIABLES
Pick up Display File pointer: The Display file pointer is held as System Variables, 16396 & 16397, so this part the program is very straightforward. The HL register pair is loaded with the contents of locations 16396 & 16397, and then incremented to point to the location required for the starting character of the first line.
Construct picture: Following the example of the BASIC program that drew a simple
Assembler language LD HL, (D-FILE) INC HL
rectangle, a machine code routine must be written to draw a similar rectangle. End of line delimiting “118° must be added as required. The following algorithm is just one solution of many, and it has been chosen as it closely copies the Basic program. It is not a very efficent algorithm but it is fairly easy to follow.
N.B. The decimal machine code instruc- tion “118” has purposely been avoided, as the ZX80 will interpret it as an end of line delimiter if the machine code is stored ina REM statement. (see Chart 1)
14
Chart 1
42, 12, 64 39
Edge
Rows Line
Space
B-Line Edge-2
LD B, #32 LD (HL), #9 INC HL DJNZ, EDGE LD A, #117 INCA
LD (HL), A INC HL
LD B, #10 PUSH BC
LD (HL), #9 INC HL
LD B, #30 LD (HL), #0 INC HL DJNZ, Space LD (HL), #9 INC HL
LD A, #117 INCA
LD (HL), A INC HL
POP BC DJNZ, Line LD B, #32 LD (HL), #9 INC HL DJNZ, Edge-2 LD A, #117
Decimal machine code
54,9 (the shifted A)
35 (move to next character) 16,251 (loop until row finished) 62,117 (the top row delimiter) 60 (117 + 1 = 118)
119 (enter delimiter)
35 (move to next character) 6,10 (there are 10 rows)
197 (save the row number) 54,9 (the shifted A)
38 (move to next character) 6, 30 (30 spaces/row)
54, 0 (enter а ‘space’)
35 (move to next character) 16, 251 (loop for 30 spaces) 54,9 (the shifted A)
к (move to next character) 62, 117 (a row delimiter)
60 (117 + 1 = 118)
119 (enter delimiter)
35 (move to next character) 193 (collect row number)
16, 234 (loop for 10 rows)
6, 32 (32 characters/row) 54,9 (the shifted А)
39 (move to next character) 16,251 (loop until row finished) 62,117 (a row delimiter)
60 (117 + 1 = 118)
119 (enter delimiter)
35 (move to next character)
(32 characters/row)
Reset System Variables: There are three system variables that require to be reset after any picture.
The DF-EA and the DF-END need to be filled with the address of the first free location in the Display File, i.e. the current contents of the HL register pair, and the line counter at 16421 must be filled with the value required. (The row counter at 16420 may also need to be reset, but this is not required in the present example.)
System LD (DF-EA), HL LD (DF-END), HL LD A, #11
LD (LINE COUNTER), A
RETURN
34, 14, 64 34, 16, 64 62, 11 50, 37, 64 201
(rows unused)
SYNC Magazine
ч
Entering The Machine Code Routine: The above machine code routine has 64 instruc- tions and all these instructions must be loaded into the RAM before the routine can be called. There are many ways in which machine code routines can be stored in the ZX80 but the method used below prevents the routine from being overwritten. However never ‘i to LIST the whole program. (ме. try it. After you have SAVED it}
Now ent^, the following program.
Screen Display:
42 12 64 35 6 32 54 9 do 16 251 62 117 60 119 35 6 10 197 54 9 22 6 30 54 0 35 16 251 54 9 35 62 117 60 119 35 193 16 234 6 24 54 9 29 16 251 62 117 60 119 32 34 14 64 34 16 64 62 Ц
. 50 37 64 201
Machine code loader program:
10 REM 64locations (do not use spaces!) 20 LET CHECKSUM = 0
30 FOR I = 16427 TO 16490
40 INPUT A
50 LET CHECKSUM = CHECKSUM + A 60 POKE I, A
70 PRINT PEEK (1),
80 NEXT I
90 PRINT “CHECKSUM = ”; CHECKSUM
The following lines also need to be entered and afterwards deleted (line number and Newline) so as to scroll line 10 off the screen.
100 PRINT 101 PRINT 102 PRINT 103 PRINT 104 PRINT 105 PRINT 106 PRINT 107 PRINT 108 PRINT 109 PRINT 110 PRINT
11 Dummy Lines (or more if the above program was changed)
SAVEing the program at this stage is advi- sable.
Now the Loader Program is ready to be RUN, so enter RUN and NEWLINE.
Enter the decimalised machine code instructions carefully. The values are repeated below in the format that appears on the screen. A CHECKSUM is incor- porated for convenience. If a code has been entered wrongly, the correct value can either be entered directly using a POKE command, or the whole of the Loader can be RUN again.
March/April 1981
CHECKSUM = 4033
Once the machine code has been entered correctly, SAVE the program again. Now comes the moment of truth! Enter a line containing USR(16427). e.g. LET K=USR(16427) and the rectangle should appear.
If the rectangle does not appear go back to one of the SAVEd versions and find the error.
The best form in which to save the routine is to delete lines 30-90, and to replace line 20 with:
20 REM LINE 10 IS OFF THE SCREEN, USE LET K=USR(16427) TO DRAW A RECTANGLE.
So now SAVE the final version.
A Demonstration Program
The following extract from a mixed BASIC/Machine code Life program for the ZX80 shows the above routine at work.
10 REM (prepared as above and held off the screen)
20 LET A = USR (16427)
30 INPUT A
40IFA 1ORA 300THENGOTO30 50 LET A=PEEK(16396) + PEEK (16397) *256+34+А +((А-1)/30)*3
60 POKE A, -52*(PEEK(A)=0)
70 GO TO 30
The above program is used to enter | characters into the required positions. The program also contains the facility of removing a character by overwriting the
character with a "space".
I hope that the above article will prove useful to many readers, and I would certainly be interested in seeing any programs written as a direct result of reading this article. Г]
Are you in SYNC?
If not, you should be. We would like any programs, translations of existing pro- grams, games or tips which you have to pass on to fellow Sinclair 4 Х-80 or Micro- Ace owners. Articles are much more lively if accompained by photos (black and white), diagrams, and illustrations. If you do not have an output printer, please type program listings and carefully check them against the listing on the screen. Sample runs should be included with pro- grams rather than just a description of what the program does. Articles should be typed, double space. Your name and address, with phone number should be on first page; all other pages should be num- bered. АП submissions should include re- turn postage. Payment ranges from $15 to $40 per printed page.
Please send all submissions to:
SYNC 39 E. Hanover Avenue Morris Plains, New Jersey 07950
The magazine for Sinclair ZX80 users
Cir
1
L
4 P) ©1980 моду таужы-/
JCREPT NE COMPUTING
—
=
a
( c
T-SHIRTS! Proclaim the computer of your choice on your chest with our own Crash Cursor and Sync. Design is silver on dark blue shirt for a striking effect. Available in adult S,M,L and XL. $6.00 postpaid in U.S.A.; 3.00 postpaid in U.K. Send U.S. orders to SYNC, 39 East Hanover Ауе.. Morris Plains, NJ 07950. Send U.K. orders to SYNC, 27 Andrew Close, Stoke Golding, Nuneaton CV13 6EL.
15
Memory Display
David A. Cromely
The Memory Display Program presents | 16 Bytes of memory in binary, octal, decimal, and character. You can enter a one-to four-digit hexadecimal starting address, or hit NEWLINE, if you want to continue without a new entry. To end the display enter Z.
Address E00 (hex) houses the generator portion of the ROM, the RAM is at address 4000 (hex), and the program begins at address 4028 (hex). Lines 60 to 90 convert the hexidecimal address to decimal; lines 110 to 140 call the subroutine to print the address in hex, and lines 180 to 210 trigger the subroutine to print the memory contents in binary, while lines 220 to 240 print in octal, and lines 250 to 270 in hexidecimal. Line 280 prints the contents in decimal with leading zeros, and the character. Lines 310 to 430 convert the decimal number in X to N digits using radix R, and then prints the digits. If the radix is 2 (binary) a black or white square is printed instead of O or 1.
David A. Cromely, 5136 Redmond Road, . Cheyenne, WY 82001.
LET А 16 INPUT A$ X. IF @g="Z" THEN LIST ~a LET A= à + 14 5% IF АФ = " " THEN GOTO 100 м
) LET А = & 14 + CODE (A$) - 28
LET АФ = TLS (AS) IF NOT A$ = " " THEN GOTO 70 CLE
LET R = 14
LET М = 4
КЕТ X
GBOSUB (3
FRINT
FUR I 9 TO 193 LET К ҒА
LET М =
LET X = PEER (+1) ЕСІН ZIC
LET К =
LET М =
СС са
осо LET А =
LET М =
GÜSLIBE x TLE (ZTR$ (X + 10002)5" "s СНК
GOTO 20
LET Y
LET F
FOR 4 =
LET 0
LET Y =
LET F = F,
IF NOT К = z THEN GOTO 400 IF ПІ = 1 THEN LET П = 128 LET U = p - 25
FRINT CHRS ІП + 29): NEXT .
FRINT из
RETLIRN
CX)
Worth A Fortune
Past issues of Creative Computing. What are they worth today? It varies. Toacollec- tor, Vol. 1, No. 1 is worth $7 ог $8. То a scrap dealer, less than two cents.
But were not selling old back issues. Werre all out.
On the other hand, you know that much of the content of Creative Computing is timeless. The Depth Charge program in Vol. 1, No. 1 is just as challenging today as the day it was written. Walter Koetke's series of five articles on using computers in the classrom are as valid today as the day they first ppeared in print. And scores of people have written about obtaining re- prints of Don Pieles classic problem- solving series.
Our Mistake
In our early growth years when we had 5,000 and then 10,000 subscribers we couldn't imagine we would ever need more than 1000 extra copies for back issue sales. Thats about what we printed extra. How- ever, by the time we were going into Vol- ume 3, we found our stocks of Volume 1 issues virtually depleted.
Our Solution
So we selected the best material from Volume 1, edited it, put it together in book form and sold it for $8.95, about the same as the six individual issues. Nine months later, we did the same with Volume 2. Then a year and a half later we did it again with Volume 3.
Most other magazines in a high tech- nology field like small computers find their contents are quickly out of date. However, because we ve concentrated on applica- tions and software, our content retains its value for a much longer time. Our sub- scribers know this and retain their copies of Creative Computing long after they ve dis- posed of the more hardware-oriented magazines.
Now you can obtain the best material from the first three years of Creative Com- puting in book form and the next three years (minus four issues) in the original magazine form.
Our Offer
We have a unique special offer, so pay close attention to this paragraph. (Compu- ter types ought to be able to understand this). If you order any one item below, you pay the full price. If you order any two items, take a 5% discount from the total; any three, take a 10% discount; any four, take a 15% discount, any five, take a 20% dis- count, and on all six take a whopping 2595 discount from the total price.
Best of Creative Computing-Vol 1 $8.95 Best of Creative Computing-Vol 2 8.95 Best of Creative Computing-Vol 3 8.95 Volume 4 (Four issues) 6.00 Volume 5 (Ten issues) 15.00 Volume 6 (Twelve issues) 18.00
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We guarantee you'll never find a better value in computer applications reading matter. On average you're getting 128 pages of solid information for each $1.00. If you re not completely satisfied after you've read them, send the books or magazines back to us and we'll refund your full pur- chase price plus the return postage.
Greative competing
Morris Plains, NJ 07950 Toll-free 800-631-8112 (In NJ 201-540-0445)
March/April 1981
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17
Truth In Programming
It's time for a little truth in programming, time for a bit of logic. Why let your programs slave away with boring numbers when they can deal with such fascinating concepts as truth and falsity? The logical capabilities of the Sinclair represent one of the best ways to shorten and speed up programs. Many programers don't make full use of these Boolean operators, mainly because, while they are not difficult to use, they are different from other parts of Basic. Boolean logic uses operators such as "AND" and "OR." The major ways to use these operators will be discussed below.
Logical operators deal with the concepts "true" and "false". In the Sinclair, true is represented as -1, false is represented as 0. This is just a convention; some machines use 1 for true, some use 0 for true and 1 for false. Knowing how the Sinclair represents true and false, the next question is, what makes something true or false? In Basic. any expression or variable with a value of 0 is false, any other value is considered true.
There are many ways to use logical operators. Let's start with a simple example. Take the statement 10IF X > ООВХ < 0 THEN GO TO 50. This could be replaced with 10 IF NOT X — 0 THEN GO TO 50. But there is an even shorter way to perform the operation. We want to take the branch whenever X is not equal to 0. And, if X is not equal to zero, X is considered to be true. Using this, we can perform the function with the following line: 10IF X THEN GO TO 50. The IF... THEN statement makes the branch only when the IF part is true. If
18
David Lubar
(LET X=Y=Z=W)
X is not equal to 0, X is true, so the branch will be taken. Only when X is zero will the branch not be taken. Conversely, the statement 10 IF X = 0 THEN GO TO 50 can be replaced with 10 IF NOT X THEN GO TO 50. You can use this technique to check against numbers other than zero by changing the variable to an expression. For example, IF NOT X = 15 THEN GO TO 100 is equivalent to IF X - 15 THEN GO TO 100. When X is not equal to 15, the expression X - 15 will evaluate as true, and the branch will be taken. What the above example boils down to is this: the IF...THEN statement can be used with any logical operation.
Another important aspect of logical operators is their ability to provide a value that can be used to advantage in a program. Remember that true is represented as -1 and false is represented as 0. Take the following programming problem: a player has to guess whether a number is odd or even. The program must determine whether the guess is correct. The first step would be to get the guess. This could be done with:
10 PRINT "ODD OR EVEN?"
20 INPUT G$ Now, some way has to be used to compare the guess with the number. This brings up another problem: what is the simplest way to determine whether a number is odd or even? In integer arithmetic, an easy way is provided by the fact that division rounds off a number to the integer remainder. The result of dividing 7 by 2 would be 3. This gives a way to determine whether the
number is odd or even. For any integer N, if N/2 — N- N/2, then the number is even. Try this with an odd number, then with an even one. N/2 will only be equal to N - N/2 when N is even. Now we could use lines such as 30 IF N/2 — N- N/2 AND G$ — "EVEN" THEN GO TO 100, where line 100 handles a correct guess. But the full comparison of guesses in this manner seems somewhat long and inelegant. Instead, we can take advantage of the values given to logical operations. It happens that the CODE for E is 42 and the CODE for O is 52. If we can find an expression that produces a value of 42 when the number is even, and 52 when the number is odd, we can compare this value with CODE (G$) to determine whether the guess is correct. This can be done using the fact that (N/2 — N- N/2)is true when N is even and false when N is odd. Since true gives a value of -1 and false a value of 0, the comparison can be done with the following line:
30 IF CODE (G$) = 52 (N/2 = N - N/2) *
10 THEN GO TO 100
Since even numbers will cause the expres- sion in the parentheses to be evaluated as - 1, the result will be 52-1* 10 thus matching the CODE for E. If the number is odd, the result will be 52 +0* 10, matching the CODE for O.
This concept bears repeating: airthmet- ical operators can be used to return logical values. АП in all. a very valuable technique. It can be used to adjust scores in games or alter results depending on answers. Since false returns a value of 0, and multiplying any number by zero results in zero, when
SYNC Magazine
you add a logical expression multiplied by a constant to a number, the number only changes if the expression is true.
The equal sign can also be used more than once in a line. This fact caused a bit of confusion when mentioned in the ad for SYNC magazine, and deserves a fuller explanation. LET X — Y — Z is a valid expression, but does not assign to both X and Y the value of Z. These variables must be defined first. (To take an analogous case, LET X = X 1 is valid, but will cause an error if X hasn't been defined.) What the expression does is compare Y to Z and give X the logical value of this comparison. If Y equals Z, X will be assigned the value of -1. This fact can be exploited when a program requires several IF... THEN state- ments that all use the same comparison. For example:
10 IF Y = Z THEN LET T=T +1
20 IF Y = Z THEN PRINT “YOU ARE
RIGHT”
Assume that several more uses of this
comparison are made later. These can be
replaced with:
10LETX=Y=Z
20 IS X THEN LET T = T + 1
30 IF X THEN PRINT “YOU ARE RIGHT”
In the above example, no space was saved.
But if the program makes repeated use of
the comparison, this trick will save space
since the expression IF X is shorter than
the expression IF Y = Z. Also, the shorter
version will execute more quickly since it has less to perform.
While arithmetical operators can be used to produce logical values, there are also certain functions that are used specifically for logical operations, namely AND, OR, and NOT. AND is considered true only when all expressions linked by it are true. OR is true if at least one of the expresions linked by it is true. So the statement IF X AND Y AND Z THEN GO TO 100 will take the branch only if all three variables have a value other than zero. If any one of the variables is zero, the expression will be false. Again, the value produced by this expression can be used in arithmetical operations. The statement LET A = (X AND Y AND Z) * 10 will give A the value - 10 if X, Y, and Z are all true. If any of the three are false, A will have a value of 0.
These operators can be combined, producing lines such as IF NOT (A AND B) OR C THEN GO TO 100. While such expressions seem complex at first glance, they become simple when evaluated in sections. The first step would be to look at anything in parenthhses. A AND B by itself is simple. As stated before. this expression is true only if both A and B are true. NOT (A AND B) has the opposite value of (А AND B). 50, if (A AND В) is false, NOT (A AND B) will be true. Now, the entire expression can be understood.
It is true if either NOT(A AND B) is true or if C is true. To test your understanding
of this, determine, before looking at the next paragraph, what logical values of the
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Add $2.00 for air mail freight and shipping. Master Charge credit cards accepted.
PHIPPS ASSOCIATES з. DOWNS AVENUE, EPSOM, SURREY, ENGLAND. WEN
or Telephone Epsom (03727) 21215 Quoting your Access Card Reference. No callers please.
POCKET BOOK
Subroutines
variables would make the expression false.
Since the major connective in the expres- sion is an OR, the expression will be false only when both sides of the OR are false. So C has to be false. NOT (A AND B) must also be false. NOT (A AND В) is fale when (A and B) is true. (A and B) is only true when both A and B are true. So, when A is true, B is true, and C is false, the expression will be false. With any other values, it will
be true. | Logical operations make an excellent
addition to a programmer's bag of tricks. They can be used to shorten programs, speed up programs, and to perform things that would otherwise require great
difficulty. o
Including Postage & VAT
Cassette Tape of Programs above plus book. £14.95
кесте
DATA Statement Simulation
One of the most noticeable short- comings of the Z X80 Basic is that there are no DATA statements.
With numbers it is possible to simulate
the DATA, READ and RESTORE
instructions by a simple program.
This can be done using a REM state- ment. The numbers are placed in a list within the REM statement, as is done with DATA statements, separating each number by a comma, and ending the list with a comma.
The DATA is then read by PEEKing the number out of the REM statement and placing it in a variable, as demon- strated in Demo 1.
R. Turner, 396 James Reckitt Avenue, Hull, N.
Humberside, HU8 ОЛА, England.
10 REM 12. 08. -2145, 11 LET D = 9
iS LET C = 0
14 LET E = 20 GÜSUB 100 22 IF D= 1 ӘЗ LET пе Ó z5 LET E = А + E + 1 30 PRINT C
40 LET C = 0
во — INPLUT A$
70 вата 20
cO УГЕ"
100 FOR à = О TO 100
LLO LET B = РЕЕК(Е + А) ~ 120 ТЕ B = 188 125 IF В = ФО THEN STOF
126 IF NOT В = 192 THEN GOTO 120
іре LET O = 1
127 GOTO 140 130 LET C = C # 10 + R
Do not use variable A, B, C, D, OR E elsewhere in the program.
Variables
A —Dummy in FOR/NEXT loops B—Number read from REM statement should be PEEKing
C— Number read from DATA statement D —Sign Flag + (0) - (1)
E— Pointer to next number on DATA list
20
THEN RETURN
Richard Turner
In this case the number is put into variable C. This may then be put into any other variable by using a LET statement such as:
LET А(2) = C
E stores the pointer to the next item of DATA and in this case the start of DATA is at memory location 16427.
LET E — 16427 this will act as the RESTORE statement.
The DATA can be placed anywhere in a program, but the memory location of the start of the data must be found.
The following program finds all the REM statements in a program and prints the memory location where the data will start. Type this in at the end of a program and then erase it after it is used. []
DATA STATEMENT
FLAG FON + UR - NL. NO. READ FROM LATA BEGINNING OF HATA EXTRACT FIRST NUMER
{) ? = 1 3
THEN LET C = -Ë [3 D SET? IF 50 CHANGE SIGN
RESET FLAG PUINTER TO NEAT Ми, No. FROM DATA
ПМ DATA
РКЕ NEWLINE іш EATRALT NEAT NUMBER
Bere trm
CHECK FOR COMMA
CHECK FOR END Gr LINE CHECK FOR MINUS SIGN SET FLAG
SOOO JOLO
LET A = ҒРЕЕК(163У2) + FUR He 16424 TU à
голо TF FEEEKCBO = 254 THEN FRINT В
S030 NEXT В
The use of this simulation means that one of the faults of the ZX80 Basic may be easily rectified.
PEER ILOJ
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* 1
SYNC Magazine
EM
A one-hour LP record of eight synthesizers may change your views about computer music forever
Binary Beatles
by David Ahl
Computer music. Who needs it? It's mostly boring beep, beep, beeps or wildly modern stuff. It's certainly nothing you'd want to listen to more than once. That's what | thought about computer music and most of my friends agreed.
In 1978 | entered Yankee Doodle Dandy into my Software Technology system just to be different. Dick Moberg heard of itand asked me to perform in the Philadelphia Computer Music Festival. | agreed expecting to be the only one with something out of the ordinary. | was wrong.
Computer Accompanist
Nine individuals and groups performed in the festival. There were the usual Bach pieces but even they were different. Gooitzen van der Wal performed the last movement of the 2nd Bach Suite in a unique way. He played the flute solo while using the computer as accompaniment.
Then Dorothy Siegel did the same thing, playing the clarinet solo part of Wanhal's Sonata in b flat. The audience went wild.
Hal Chamberlin played Bach's Tocatta and Fugue in d minor. Butalso with a differ- ence. He used a large computer before hand to "compute" the waveform of every
instrument playing every note. It took one hour of computation time for each two min- utes of playback time. The result could hardly be distinguished from the organ in the Hapsburg Cathedral.
Don Schertz had a home brewed synthe- sizer truly mounted on a breadboard that allowed him to control 25 parameters of each note. It produced spectacular sounds in his arrangement of Red Wing.
Singing Computer
In 1962, D.H. Van Lenten at Bell Labora- tories produced the first talking computer. Bell engineers taught it to recite the soliloquy from Hamlet. Then they went one step further and taught it to sing Daisy both alone and accompanied by another computer. This was also performed at the festival.
Yes, the Beatles were represented. Andrew Molda played Hey Jude on his COSMAC VIP system with a program called PIN-8 (Play it Now).
Superb Quality Recording
All these pieces and twelve others were recorded with broadcast quality equipment. Because of audience noise, eight were re- recorded later in a studio. We then took these tapes to Tru-Tone, a top recording
KNOW YOUR ZX80
With LINSAC products for the Sinclair ZX80
THE ZX80 COMPANION (Second Edition)
Maunder, Logan and Trotter
THE ZX80 COMPANION
postage.
The ZX80 Monitor A complete assembly language listing of the ZX80's 4К Monitor,
with annotations — Price £10.00 incl. UK postage.
Cassette Software
All LINSAC program packs are on single C12 cassettes with printed run instructions. All run on 1K ZX80's unless otherwise
stated. Price £10.00 per pack incl. UK postage.
ISBN 0 907211 00 3. Price £7.95 incl. UK
This best-selling manual on the Sinclair ZX80 covers ZX80 BASIC, hardware and programs and has a detailed explanation of the ZX80 Monitor, routines and entry points. A routine for generating moving displays is also included.
Ch.1 — Operating the ZX80.
Ch.2 — Theory of Computers
Ch.3 — ZX80 BASIC
Ch.4 — The ZX80 Monitor
Ch.5 — Construction and Hardware
Ch.6 — ZX80 Programs
App.1 — Comparison of Z-80 Opcodes and ZX80 Characters.
App.2 — The 8K ROM.
For a cassette of ten programs from the Com- panion add £4.95.
studio and cut a lacquer master. It was a
long session since the recording engineers .
insisted upon analyzing the sound from every source and setting up the equilization curves accordingly. It took over 12 hours to produce a one-hour lacquer master.
Finished recordings were then pressed on top-quality vinyl and inserted into liners and record jackets. These were then shrink wrapped in plastic for maximum protection. We guaranteee that every LP record is free from defects or we will replace it free of charge.
The extensive descriptions of each of the eight synthesizers and the festival would not all fit on the jacket so we ve included an extra sheet with each record. This entire package is mailed ina protective corrugated package to insure that it reaches you in mint condition. The cost is a modest $6.00 postpaid in the U.S. and $7.00 foreign. Send order with payment or Visa, MasterCard or American Express number to Creative Com- puting, Morris Plains, NJ 07950.
This LP record contains one hour of eight computer music synthesizers that you'll listen to over and over again. Send in your order today at no risk whatsoever.
creative сора юр
Morris Plains, NJ 07950 Toll-free 800-631-8112 (In NJ 201-540-0445)
NOW AVAILABLE
ke
GAMES PACK 1 — Three Towers, Number Guessing, Mastermind, Sketcher, Hurkle, Nim, Symbol Simon.
GAMES PACK 2 GAMES PACK 3 (2K*) — Fruit Machine, Four-in-a-line, Zombies EDUCATION PACK 2 EDUCATION PACK 3 UTILITY PACK 1
(2K*) — CAL Quiz Package with three sample data sets.
Nine Lives, The Maze Game, Plain Sailing, OXO, Chinese Puzzle, Tower of Hanoi, Battleships.
EDUCATION PACK 1 — Maths Drill, Dot Recognition, Musical Notes, Spelling Quiz, Day Finder.
Graph Plotter, Prime Factors, Number Bases, Bar Charts, Statistics.
Memory Display, Hex Code Monitor, Renumber, Memory Search.
LINSAC
68 Barker Road, Linthorpe,
Middlesbrough, Co. Cleveland TS5 5ES
March/April 1981
board . conversions
Standard Compute
minutes
inversion with reverse video
Keyboard with complete parts and plans $65.00 Wired keyboard, complete with plans $85.00 а nS SEE RNS ЗЕНА ЕЕ ЖЕ S О ы м о Е
Mail for information:
L.J. H. Enterprises
P.O. Box 6273, Orange, CA 92667
21
Is it possible for a game to present an interesting challenge, yet fit in 1K of RAM? As evidence that the answer is "yes," I offer Widget, a relative of the games Hammurabi and Lemonade Stand, in which the player allocates his resources for the best effect. As the player, you are the head of the United Widget Company, trying to expand your business as rapidly as possible without going broke.
You start out with one plant and $90,000. A plant is capable of producing as many as 1000 widgets a month, which will sell for $10 each. The monthly fixed overhead is $4000, including the mortgage cost for your first plant. In addition, it costs $5 per widget to produce any widgets in excess of the first hundred. To sell any widgets, you have to advertise. Naturally, the return on advertising isn't entirely predictable, but you have to learn how much to spend in order to sell what you produce аға profit.
The key to making money is buying more plants. A plant costs $100,000 to buy and $2000 a month to maintain, and it lets you produce another thousand widgets a
22
cet
Gary McGath.
ACME- * WIDGETS inc.
Some of the many versions of Widget as 4
illustrated bv Timothy Truman.
| у, A UT
month. This means more fixed cost and more need for advertising; it also means economies of scale. You'll notice that as production increases, it takes more adver- tising dollars to sell each widget. On the other hand, if you keep a steady flow coming out of your plants, each month's sales will produce a carry-over effect into the next month.
With these costs in mind, you can start playing Widget. Each turn represents one month. At the start of the turn, the screen shows your current cash balance, number of plants, and inventory. If you have at least $100.000, you are asked, "Buy a plant?" To buy a plant, answer “У” (just the one letter); anything else means "no."
Next (or first, if you had less than $100,000). the program asks for your ad budget. Enter the number of thousands of dollars that you want to spend on ads; for example, to spend $4000, enter “4.” You will be asked again for input if you try to spend more than you have.
Finally you are asked how many widgets you want to produce. Enter the number of
hundreds of widgets you want to produce, remembering that each plant can only produce 1000 widgets. Again, the program wont let you go until you've entered а legal number.
The advertising cost is then subtracted from your cash balance, sales are deter- mined, revenue comes in, and then the other costs are subtracted. If you can't meet your costs, the message "You are bankrupt" appears, and the game is over. Otherwise, the program goes on to the next month.
Before starting, decide how many months you're going to play. Sixty turns (5 years) or 120 turns (10 years) make a good game. Keep score by calculating your company's net worth, which is its cash balance plus $100,000 per plant. There isn’t any prede- termined winning score, but the outcome of a fairly well-played game would be to have 5 plants and $50,000 or more at the end of 10 years. []
Gary McGath, 5 Ames Rd., RFD #3, Milford, NH
03055.
SYNC Magazine
Zu s «t ]
= RANLDCGMIZE 6 LET Z = 1 10 LET F = 1 20 LET M = 770 О LET I = 0 40 LET $ = 10 joo CLS 110 PRINT "MONTH" „7 120 LET Z = Z + 1 300 PRINT "YOU HAVE" , "$" :M; "OO" 310 PRINT F3" PLANTS" 320 PRINT »15 "00 WIDGETS" 330 PRINT "LAST MONTH You SOLO "sm; "oo" 250 IF M x 1000 THEN ба та 410 360 PRINT "BUY А PLANT?" 370 INFLT YS 250 IF NOT Y$ = "Y" THEN GO Та 410 390 LET Р = Р + 1 400 LET М = M - 1000 410 РКІМТ "АП BUDGET IN 10005 7?" 420 INPUT В 430 IF B * 10 > M THEN GO та 420 440 LET М = М ~ B * 10 450 FRINT "PRODUCTION IN 1005 7" 470 INFUT W 430 IF W > 10 * Е THEN GO To 470 470 LET I = I + W 200 LET & = $ / (RNE (3) + 3) 210 IF B = 6 THEN GO та 550 ЭРО LETS = Б + (В - 6) * 5 "30 LET В = 6 SAO IF В < Т THEN GO TO 400 S60 LET $5 = 5 + (В - 2) # 7 70 LET B= 2 4200 LET 5 = 5 + БВ * B 4140 IF С > I THEN LET 5 = I 420 LET М = М +5 # 10 630 ЕТІ = I-$S 640 LET М = М ~ zo * P — zo 450 LET M =M- (W - 1) * & 640 IF NOT M О THEN ба TO 100 зоо PRINT "YOU ARE BANKRUPT. " MONTH 1 УГ! HAVE $70000 1 FLANTS
ООО WIDGETS
LAST MONTH YOu SOL TI 1000
АП BUDGET ІМ 109057 MONTH 29 YOU HAVE 101000 1 PLANTS 000 WIDGETS LAST MONTH YOU SOLD 1500 BUY A PLANT? MONTH 61 УГ HAVE $71000 2 FLANTS
200 WIDGETS
LAST MONTH YOu SOLE 1900 AD BUDGET IN 10005?
MONTH au УП HAVE $0000 3 FLANTS ооо WIDGETS LAST MONTH YOU SOLD 2600 АП BUDGET IN 10005?
MONTH 121
УГ
LAST BUDGET IN 1000027
AL
HAVE $53000 к FLANTS 400 WIDGETS MONTH YOu SOLD Shoo
March/April 1981
OULMLITY SOF TMLRE
Graphics ў ( #5 ) Poke to memory mapped screen - use your ZX80 as а Sketching pad. Character and direction control. Music
( #15 ) Tunes to your cassette recorder, with selectable octaves, semitones and duration from a wide range of notes. Your tune will repeat itself continuously. For the best results, memory 1K is necessary.
Po QUT ЖЕНЕ) ( £5) Hex. Loader - this routine provides а simple means
for machine code programming in Hexadecimal notation. А 'String Rotate' demonstration program is included. Hex. Display - this routine allows you to inspect
the contents of memory in 64 byte blocks - just
enter the decimal address.
е Display ;
( $20 ) Write your own games or use the ZX80 for continuous data monitoring. You decide how long a dísplay will hold before your program continues (1/60th second to approx. 16 mins.). A Hex. Loader and а 'top row' keyboard scanning routine is included with a demo.
Жалбыр;
( $20 ) Try your skill at knocking all the bricks from the wall before your final ball is lost. The ball starts at '9' and decrements each time it is lost until the
game is over. The paddle moves swiftly under your
control - the game restarts automatically.
Movies
( #15 ) Pictures of your own creation (7x8 characters) are displayed in rapid rotation giving animation effect. For the best results, memory 1K is necessary.
әсе E йыз
( #25 ) A simplified version of the famous arcade game. Zap the intruders as they attempt to land. The impulse to beat your last score is paramount. Requires 2K memory.
No modifications to hardware whatsoever. All software is thoroughly tested and claimed to be the most advanced developed so far.
Games are written in machine code to make maximum use of memory and provide continuous live action without loss of T.V. synchronisation. All programs run in 1K memory unless stated otherwise.
Inclusive prices for program listing, details and Air Mail postage, (Send only $90 total if all the software listed is ordered together). Cheques (or S.A.E. for U.K. price list and details) to:- K.Macdonald, 26 Spiers Close, Knowle, Solihull, West Midlands, B93 9ES, ENGLAND.
Rose Cassettes
R.F. SHIELD
(Cuts down T. V. interference)!
TUITION for your under 13 year old child. Make itfun to learn Maths., English, General Knowledge and Reasoning. 4K ZX80 — Cassette $10.80. Also
GAMES cassettes (4K) $10.80 and (1K) $4.80.
Mailing and packing $1.80. Check to ROSE CASSETTES,148 Widney Lane, Solihull, West Midlands B91 3LH. England.
WYNCOM
WYNDHAM COMPUTER SERVICES
Languages, History, mathematics: WYNCOM's TUTOR program stores questions on any subject, presents them in random sequence. 1K ver- sion displays answer, 2K checks student’s response. Listing 1K $7 (£3), 2K $12 (£5) from WYNCOM, 11 Furze Platt Road, Maidenhead SL6 7ND, England.
Kit for the ZX-80 ог Micro-Ace. Send $5.00 U.S.A. To:
Outbound Engineering P.O. Box 218 Chandler, Texas 75758 U.S.A.
Why wait 2 or 3 weeks for your check to clear? Send Cash. Texas residents add 595 Sales Tax.
23
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In Artillery the player fires a cannon at a stationary target. The screen displays the gun location, the target site, and the approximate range. To take aim the cannon- eer selects the angle at which the cannon is raised, between 0 and 90 degrees. The display then indicates whether the shot was long, short, or on target.
With a maximum range of just over 200,000 yards — the display gives a relative range within approximately 10,000 yards.
C.R. Whetstone, 211 Clarendon Ave., Baltimore, MD 21208.
March/April 1981
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1 TD 20
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R €=1 T2 20 S€Q)=1 THEN 5С642:2 THEN SCQ223 THEN та
NT "M/R" URN
NT "TARGET RANS NT
508 140
МТ
NT "INPUT GUN UT N М<0 N»45
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29
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S=C TREN GO TC
NT "RANGE =";
NT
593 150
INT "YOU WERE "SZ ASSCA-LD3 "O00 А-1>0 THEN PRINT “SHORT"
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27
Game of Life
pe нн C —————— á— —— ead el p
Generally, a mathematical model is a representation of some real-life process, expressed in mathematical form (such as a set of related equations) or in algorithmic form (such as a computer program). Usually the model is by necessity a simplification of the actual process, since real-life pro- cesses tend to be highly complex. One advantage of embodying the model as a computer program is that we can run the program and thus simulate the process being modelled. By varying certain features of the program, we can learn something about the relationships between the compo- nenets and the overall structure of the process. In addition, if the output does
(1) World — Cells live on an infinite two-dimensional plane of squares (like an infinite checker-board, except that all squares are identical).
not sufficiently coincide with observed reality, the model can be revised and improved.
It is also possible to model a purely abstract process. We don't often see this done. After all, if someone asked you to describe some abstract process, what would you say? However, many games start out as purely abstract processes. For example, tic-tac-toe or checkers are abstract from the point of view that they represent no real-life process. Occasionally, it turns out that an abstract process represents a real- life process either by accident or design. The following game is one such example which in some ways represents life itself.
(2) Neighborhood — Each square has eight neighbor squares. In the diagram below, the neighbor squares for the square with the asterisk (*) have been colored in.
The game of Life was devised by John Conway, a mathematician at the University of Cambridge, and made popular by a series of articles written by Martin Gardner in recent issues of Scientific American. Ever since the first article appeared in October 1970, hundreds of mathematicians throughout the world have become fasci- nated with the model and have been exploring its properties.
The game consists of following the successive generations of a particular imaginary type of cellular life-form. The life processes of these cells are represented by the following mathematical model,
(3) Survival — A cell (always represented by a *) which is living in generatin n, will remain living in generation n+1 if and only if it has exactly two or three living neighbors in generation n.
(4) Death — However, in all other cases the cell dies. Specifically: If it has one or no neighbors it dies from isolation. If it has four, more than three neighbors, it dies from overpopulation.
(5) Birth — If a square is empty during generation n, a living cell will be born into that square during generation n t 1 if and only if that square had exactly three living neighbors during generation n.
The only trick is to remember that all survivals, deaths, and births occur simul- taneously, and so the simplest way to keep the bookkeeping straight is to have two separate copies of the world — one for the old generation and one for the new one you are forming. For each square in the old world, decide what its state will be next time, and mark this down in the corresponding square in the new world.
SYNC Magazine
which captures several properties common to all life-forms.
The game is played simply by picking some initial starting pattern and watching the development of some very interesting, and often beautiful patterns of symmetry. However, the player must be extremely careful because mistakes are easy to make.
As an example, we will trace three generations of the following initial pattern (we have numbered some rows and columns for reference purposes only):
Following the rules of our model:
No births will occur in squares 1, 2, 3, 4, or 5 because none has three living neigh- bors.
The cell in square 6 will survive because it has two living neighbors (10 and 11).
A birth occurs in square 7 because there are three living neighbors (6, 10, and 11). No birth occurs in squares 8 or 9.
The cell in square 10 survives because it has three living neighbors (6, 10, and 15). The cell in square 11 survives also because it has three living neighbors (6, 10, and 15).
No birth occurs in squares 12 or 13.
A birth occurs in square 14 because there are three living neighbors (10, 11, and 15).
The cell in square 15 survives because it has two living neighbors (10 and 11).
No birth occurs in square 16 because it only has two living neighbors.
During this process, we have been filling in a picture of G1, and the end result is:
FOO
joo DIM A (63)
110 FOR I = 1 TO 4&3
120 LET ACI) = 128 # (КМО (2) - 1)
1:0 NEXT I
200 FOR L = 0 TO &
210 FOR J = 1 To 7
220 LET IT = J + 7 #L
2530 FRINT CHR$ (ACT) )3 The following program for the game of 240 NEXT 4 Life is from The Melbourne House book, 250 FRINT Thirty Programs for The Sinclair 2 Х-80 260 NEXT L IK.
270 PRINT "PRESS 1”
шо INFUT А
270 CLS
300 Е N R I= 70 55
210 LET X = О
azO IF ((I + 1) АМП 7) = О THEN са TO 230
S30 LET X = (ACI + 1) > 127)
340 IF ((І - 1) АМП 7) = о THEN GO TO 340
220 LET X = X + (ACI ~ 1) „> 127)
360 FOR d 7 TO F
370 FOR К = — 1 TU 1
зао IF R = О THEN GO TO 420
290 LET Е = I + К * Jd
400 IF (к АМП 7) = Q THEN GO TO 420
410 LET X = X + (ACK) 2127)
420 NEXT К
4x0 NEXT 41
440 LET ACI) = ACI) - X
460 NEXT I
470 IF ACI) = 3 OR ACI) = 130 OR ACI? = 131 THEN GO TU 420 LET ACI) = O
470 GO Та 510
200 LET ACI) = 128
10 NEXT I
220 GO TO #900
March/April 1981
29
Life, continued...
Experiment 1
Using pencil and paper, carefully com- pute G2, the next generation for this same society of cells. If you do it cor- rectly, you will find that G2 is the pattern which Conway calls the “Беешуе”:
Experiment 2
Now compute G3. If you are again careful, you will discover that G3 is iden- tical to G2. Why does Conway call the beehive a “still-life”? If you are not sure, think about G4, G5, бб...
Experiment 3
Using pencil and paper, compute GO, G1, G2 and G3 for the initial pattern below:
If you do it correctly, G3 should look familiar to you.
Experiment 4
By now you've no doubt noticed that with pencil and paper, this game is an extremely slow process, and mistakes are all too common. If we ever hope to look at more than a few patterns, we're going to have to turn to the computer for help.
Write a computer program which
simulates "Life" for any given initial pat- tern, and which has the following features: (1) Allow for as large a world size as your particular computer facility will permit (obviously an infinite plane is not pos- sible in a finite memory). You will prob- ably want to use array structures with two subscripts (row and column).
30
(2) Whatever world-size you are limited to, make sure your program doesn't try to alllow births outside your world, even though properly these would occur on an infinite plane.
(3) Make sure your algorithm allows all survivals, deaths, and births during a given generation to occur simulta- neously, as discussed above.
(4) Allow the user to input the initial pattern in a convenient format, such as pairs of (row, column) coordinates.
(5) Make your program efficient and your output as close to the format of the pictures above as possible.
Once your algorithm is designed, and your program is written, debug your pro- gram by running it on the following initial GO pattern, and carefully check your output vs. the results below:
Warning !
Depending upon the world-size you are limited to, certain "large" patterns may grow differently than they would on an infinite plane.
If the society of cells above, however, fits inside your world-size, you will notice an interesting cyclic pattern beginning at GO, which Conway calls “traffic lights".
Experiment 5
When your program is thoroughly de- bugged and operational, or using the LIFE program with this article, the real fun comes in thinking up initial patterns and watching them grow. Interesting situations to watch for are:
(1) Other “still-life societies (like the "bee-hive")
(2 Other "cyclic" societies (like the "traffic lights")
(3) A society which lives for an extended period of time without dying, becoming still, or cycling
Experiment 6
Find copies of the October 1970 and/ or February 1971 issues of Scientific American and read Gardner’s articles on "Life." You may want to run your pro- gram on some of the societies he de- scribes, such as: diagonal chains, the R pentomino, the Latin cross, the cheshire cat, and many others.
Experiment 7
Try to think up changes in the model (and your computer program) which will drastically alter the life patterns of the cells, i.e. by modifying the rules for birth or death or both. Based upon your ex- perience so far, try to come up with sets of rules which will lead to more populous societies, or more sparse societies, ог societies which are less symmetric than those of "Life", etc. The range of possi- bilities is very large.
Experiment 8
Make some major modifications in your computer program to make it more general, by allowing the user to specify the particular model he wants to investi- gate. For example, you might have your program begin by posing the following questions to the user:
How many neighbors for survival? How many neighbors for birth?
Then, if the user answered 2, 3 for the first question and 3 for the second, your program would follow the rules of "Life." But if he gave other answers, the program would simulate for him some other model he wants to investigate.
Experiment 9
Is there any way you can streamline your program or the published one so that you can enlarge the size of the world it currently handles?
Experiment 10
How might you alter the general con- cept of "neighborhood" so that entirely different models could be tested? How would your computer program have to be changed in order to simulate these new models?
SYNC Magazine
The story behind the two best selling computer games books in the world.
Computer
Games
by David H. Ahl
Everybody likes games. Children like tic tac toe. Gamblers like blackjack. Trekkies like Star Trek. Almost everyone hasa favor- ite game or two.
It Started in 1971
Ten years ago when | was at Digital Equipment Corp. (DEC), we wanted a pain- less way to show reluctant educators that computers weren't scary or difficult to use. Games and simulations seemed like a good method.
So | put out a call to all our customers to send us their best computer games. The response was overwhelming. | got 21 ver- sions of blackjack, 15 of nim and 12 of battleship.
From this enormous outpouring | se- lected the 90 best games and added 1 1 that | had written myself for a total of 101. | edited these into a book called 101 Basic Computer Games which was published by DEC. It still is.
When I left DEC in 1974 | asked for the rights to print the book independently. They agreed as long as the name was changed.
г--л---------------------------------ӘНҺмНӘӘЭӘӘӘ-- UU
Contents of Basic Computer Games (right)
Introduction Hi-Lo The Basic Language High І-О Conversion to Other Hockey
and More Basic Computer Games (below).
Artillery-3 Life Expectancy Baccarat Lissajous Bible Quiz Magic Square Big 6 Man-Eating Rabbit Binary Maneuvers Blackbox Mastermind Bobstones Masterbagels Bocce Matpuzzle Boga Il Maze Bumbrun Millionaire Bridge-It Minotaur Camel Motorcycle Jump Chase Nomad Chuck-A-Luck Not One Close Encounters Obstacle Column Octrix Concentration Pasart Condot Pasart 2 Convoy Pinball
Corral Rabbit Chase Countdown Roadrace Cup Rotate Dealer's Choice Safe Deepspace Scales Defuse Schmoo Dodgem Seabattle Doors Seawar
Drag Shoot
Dr.Z Smash
Eliza Strike 9 Father Tennis
Flip Tickertape Four In A Row TV Plot Geowar Twonky Grand Prix Two-to-Ten Guess-lt UFO
ICBM Under & Over Inkblot Van Gam Joust Warfish Jumping Balls Word Search Puzzle Keno Wumpus 1
L Game Wumpus 2
March/April 1981
Basics Horserace Acey Ducey Hurkle Amazing Kinema Animal King Awari Letter Bagels Life Banner Life For Two Basketball Literature Quiz Batnum Love Battle Lunar LEM Rocket Blackjack Master Mind Bombardment Math Dice Bombs Away Mugwump Bounce Name Bowling Nicomachus Boxing Nim Bug Number Bullfight One Check Bullseye Orbit Bunny Pizza Buzzword Poetry Calendar Poker Change Queen Checkers Reverse Chemist Rock, Scissors, Paper Chief Roulette Chomp Russian Roulette Civil War Salvo Combat Sine Wave Craps Slalom Cube Slots Depth Charge Splat Diamond Stars Dice Stock Market Digits Super Star Trek Even Wins Synonym Flip Flop Target Football 3-D Plot Fur Trader 3-D Tic-Tac-Toe Golf Tic Tac toe Gomoko Tower Guess Train Gunner Trap Hammurabi 23 Matches Hangman War Hello Weekday Hexapawn Word
Converted to Microsoft Basic
The games in the original book were in many different dialects of Basic. So Steve North and | converted all the games to standard Microsoft Basic, expanded the descriptions and published the book under the new name Basic Computer Games.
Over the next three years, people sent in improved versions of many of the games along with scores of new ones. So in 1979, we totally revised and corrected Basic Computer Games and published a com- pletely new companion volume of 84 ad- ditional games called More Basic Com- puter Games. This edition is available in both Microsoft Basic and TRS-80 Basic for owners of the TRS-80 computer.
Today Basic Computer Games is in its fifth printing and More Basic Computer Games is in its second. Combined sales are over one half million copies making them the best selling pair of books in recrea- tional computing by a wide margin. There are many imitators, butall offer a fraction of the number of games and cost far more.
The games in these books include classic board games like checkers. They include challenging simulation games like Camel (get across the desert on your camel) and Super Star Trek. There are number games like Guess My Number, Stars and Battle of Numbers. You'll find gambling games like blackjack, keno, and poker. All told there are 185 different games in these two books.
Whether you're just getting started with computers or a proficient programmer, you ll find something of interest. You'll find 15-line games and 400-line games and everything in between.
The value offered by these books is out- standing. Every other publisher has raised the price of their books yet these sell for the same price as they did in 1974.
Moneyback Guarantee
Examine one or both of these books and key some games into your computer. If youre not completely satisfied we'll refund the full purchase price plus your return postage.
Basic Computer Games costs only $7.50 and More Basic Computer Games just $7.95 for either the Microsoft or TRS-80 edition (please specify your choice on your order). Both books together are $15. Send payment plus $2.00 shipping and handling to Creative Computing Press, Morris Plains, NJ 07950. Visa, MasterCard and American Express orders should include card number and expiration date. Charge card orders may also be called in toll-free to 800-631-8112 (in NJ 201-540-0445).
Order today to turn your computer into the best game player on the block.
Greative Gorepatirg
Morris Plains, NJ 07950 Toll-free 800-631-8112 (In NJ 201-540-0445)
31
Tic Tac Toe or
Noughts and Crosses
Jeffrey Hoffman
On a computer with a very limited amount of memory (1K) even a simple game like Tic Tac Toe might be a problem to fit. This version of the well known game is short and simple, anyone will be able to understand it. Lines 10 through 90 define the variables A$ to I$ (since there are no string arrays on the ZX80 with 4К ROM, one must use another way). Lines 120 to 160 create the familiar tic tac toe pattern using the “checkerboard” graphics symbol (located above the “A” key—you must use the "shift key"). In order to save memory, this program assumes that you know the rules of tic tac toe, and therefore allows you to enter any number you want, only actually using those between one and nine. However, you may not put an X where there is already an O (or visa versa), the computer will just take the number and go on to let your opponent go. Those people with larger memory machines can adapt this program to include a "play against the computer" mode. []
Jeffrey Hoffman, 332 Melbourne Rd., Great Neck, NY 11021.
32
10 LET А$="1" 20 LET B$-"2" 30 LET C$-"3" 40 LET D$-"4" 59 LET E$-"5" 6g LET F$-"6" 70 LET G$="7" 89 LET H$-"8" 99 LET I$="9"
10) 110 120 130 140 150 160 170 18g 19g 29g 21g
45g 460 470 48g 49g 578
FOR Q-1 TO 9
PRINT " TIC TAC ТОЕ"
PRINT Аф; "5 "5;B$;" 3 "c$
PRINT " (9 3 symbols) PRINT B "IE
PRINT en's 1G
PRINT IF Q-2*(Q/2) THEN GO TO 23g PRINT "X GOES"
INPUT C
LET Рф="Х"
GO TO 27g PRINT
PRINT "O GOES" INPUT C
LET P$="0"
LET J$=STRİ (C)
IF J$=A$ AND NOT A$=P$ THEN A$-P$ IF J$=B$ AND NOT B$=P$ THEN B$=P$ IF J$=C$ AND NOT C$=P$ THEN C$=P$ IF J$=D$ AND NOT D$=P$ THEN D$=P$ IF J$=E$ AND NOT E$=P$ THEN E$=P$ IF J$=F$ AND NOT E$=P$ THEN F$=P$ IF J$=G$ AND NOT G$=P$ THEN G$=P$ IF J$=H$ AND NOT H$=P$ THEN H$=P$ IF J$-I$ AND NOT I$-P$ THEN I$-P$ IF А%-В% AND B$-C$ THEN 47g
ТЕ A$-D$ AND D$=G$ THEN 470
IF A$-E$ AND E$-I$ THEN 47g
IF В%-Е% AND E$-H$ THEN 470
IF C$-F$ AND F$-I$ THEN 47g
IF D$-E$ AND E$-F$ THEN 47g
IF G$-E$ AND E$-C$ THEN 47f
IF G$-H$ AND H$=I$ THEN 47g
NEXT Q
GO TO 49g PRINT P$;" GO TO 5g PRINT "T I E" REM END
WON"
SYNC Magazine
The Sinclair ZX80 is innovative and powerful. Now there's a magazine to help you get
the most out of it.
SYNC magazine is different from other personal computing magazines. Not just different because it is about a unique computer, the Sinclair ZX80 (and kit ver- sion, the MicroAce). But different be- cause of the creative and innovative phi- losophy of the editors.
A Fascinating Computer
The ZX80 doesn't have memory map- ped video. Thus the screen goes blank when a key is pressed. To some review- ers this is a disadvantage. To our editors . this is a challenge. One suggested that games could be written to take advan- tage of the screen blanking. For exam- ple, how about a game where characters and graphic symbols move around the screen while it is blanked? The object would be to crack the secret code gov- erning the movements. Voila! A new game like Mastermind or Black Box uniquely for the ZX80.
We made some interesting discoveries soon after setting up the machine. For instance, the CHR$ function is not limit- ed to a value between 0 and 255, but cycles repeatedly through the code. CHR$ (9) and СНВ$ (265) will produce identical values. In other words, CHR$ operates in a MOD 256 fashion. We found that the “=” sign can be used se- veral times on a single line, allowing the logical evaluation of variables. In the Sinclair, LET X=Y=Z=W is a valid ex- pression.
Or consider the TL$ function which strips a string of its initial character. At first, we wondered what practical value it had. Then someone suggested it would be perfect for removing the dollar sign from numerical inputs.
Breakthroughs? Hardly. But indicative of the hints and kinds you'll find in every issue of SYNC. We intend to take the Sinclair to its limits and then push be- yond, finding new tricks and tips, new applications, new ways to do what couldn't be done before. SYNC functions on many levels, with tutorials for the be- ginner and concepts that will keep the pros coming back for more. We'll show
you how to duplicate commands avail- able in other Basics. And, perhaps, how
to do things that can't be done on other machines.
Many computer applications require that data be sorted. But did you realize there are over ten fundamentally differ- ent sorting algorithms? Many people settle for a simple bubble sort perhaps because it's described in so many pro- gramming manuals or because they've seen it in another program. However, sort routines such as heapsort or Shell-
_ Metzner are over 100 times as fast as a
bubble sort and may actually use less memory. Sure, 1K of memory isn't a lot to work with, but it can be stretched much further by using innovative, clever coding. You'll find this type of help in SYNC.
Lots of Games and Applications
Applications and software are the meat of SYNC. We recognize that along with useful, pragmatic applications, like finan- cial analysis and graphing, you'll want games that are fun and challenging. In the charter issue of SYNC you'll find se- veral games. Acey Ducey is a card game in which the dealer (the computer) deals two cards face up. You then have an op- tion to bet depending upon whether you feel the next card dealt will have a value between the first two.
In Hurkle, another game in the charter issue, you have to find a happy little Hurkle who is hiding on a 10 X 10 grid. In response to your guesses, the Hurkle sends our a clue telling you in which direction to look next.
One of the most ancient forms of arith- metical puzzle is called a “boomerang.” The oldest recorded example is that set down by Nicomachus in his Arithmetica around 100 A.D. You'll find a computer version of this puzzle in SYNC.
Hard-Hitting, Objective Evaluations
By selecting the ZX80 or MicroAce as your personal computer you've shown that you are an astute buyer looking for good performance, an innovative design and economical price. However, select- ing software will not be easy. That's where SYNC comes in. SYNC evaluates software packages and other peripherals
and doesnt just publish manufacturer descriptions. We put each package through its paces and give you an in- depth, objective report of its strengths and weaknesses.
SYNC is a Creative Computing pub- lication. Creative Computing is the num- ber 1 magazine of software and applica- tions with nearly 100,000 circulation. The two most popular computer games books in the world, Basic Computer Games and More Basic Computer Games (combined sales over 500,000) are published by Creative Computing. Creative Computing Software manufac- tures over 150 software packages for six different personal computers.
Creative Computing, founded in 1974 by David Ahl, is a well-established firm committed to the future of personal com- puting. We expect the Sinclair ZX80 to be a highly successful computer and correspondingly, SYNC to be a respect- ed and successful magazine.
Order SYNC Today
To order your subscription to SYNC, in the USA send $10 for one year (6 issues), $18 for two years (12 issues) or $24 for three years (18 issues). Send order and payment to the address below or call MasterCard, Visa or American Ex- press orders to our toll-free number.
Subscriptions in the UK are mailed by air and cost £ 10 for one year, £ 18 for two years or £ 25 for three years. Send order and payment to the UK address below.
Canadian and other foreign surface subscriptions cost $15 per year or $27 for two years and should be sent to the USA address.
We guarantee your satisfaction or we will refund your entire subscription price.
Needless to say, we can't fill up all the pages without your help. So send in your programs, articles, hints and tips. Hemember, illustrations and screen photos make a piece much more inter- esting. Send in your reviews of peripher- als and software too—but be warned: re- views must be in-depth and objective. We want you to respect what you read on the pages of SYNC so be honest and forthright in the material you send us. Of course we pay for contributions— just don't expect to retire on it.
The exploration has begun. Join us.
The magazine for Sinclair ZX80 users
ш ==
39 East Hanover Avenue Morris Plains, NJ 07950, USA Toll free 800-631-8112 (In NJ 201-540-0445)
27 Andrew Close, Stoke Golding Nuneaton CV13 6EL, England
Making Music with the ZX80
The Sinclair ZX80 comes with no built- in sound device, although someday someone will undoubtedly devise a gadget for this purpose. Until then we can use programs to control sounds using the weak AM signal coming from the microprocessor. This signal was strongest at the high end of the dial.
The basic theory behind the program is the operating system “keeps tabs” on the position of every FOR...NEXT loop in the program. For example, if you write a program similar to the one below, which repeats two identical loops indefinitely (or until you hit BREAK), you will hear a trill- like sound.
10 LET X 50
го FOR I = 1 TO X 20 NEXT I
40 FUR I = 1 TO X «aO NEXT I
40 G0 TO 20
34
Richard Forsen
The tirst loop generates the higher pitch. It is interesting that a loop-within-a-loor structure will not produce the same result. The variable X represents the length of the note. Line 10 can be changed without affecting anything else but the duration of the tone. The value of 50 makes the tone last about one fifth of a second. A larger number will increase the length of time the note is played. Try changing line 10 to “10 INPUT X" and line 60 to ‘60 GOTO 20,‘ RUN the program, and input thes values: 1, 2, 5, 8, 15, 25, and 64, BREAKing after each entry. Then Add:
1 RANDOMISE
по INFUT N
10 LET X = КМП (М) 31 FOR I = 1 Ta X 32 NEXT I
зз FOR I = 1 TO X 34 NEXT I
за FOR I = 1 TO X зе NEXT I 37 FOR I = 1 TO X зә NEXT I
trying the same values.
ШШ JULIO ULL | THU UNA БИ
= —
3 a ТЛ» 2
И А 22222 Kaeo | 2
| hm ти Шү | )
s ГІ ІШІП — le
SYNC Magazine
Music Making, continued... 0001 DIM L (12) (Duration for each note)
The program can be typed in quickly 0002 DIM P (12) (Pitch for each note)
due to the excellent line editor built into 0909 PRINT "HOW МАМУ NOTES?" (Up to 12)
the ZX80. Enter the first nineteen lines, 2. "add N e notes — N)
then type 1000 FORI 1 TO Xandhit 22-0 FoR I= i TON elt-explanatory)
NEWLINE. Then press SHIFT and NEW- jasc рр "НИЕАТТНМ ПЕ NOTE!
LINE simultaneously. Line 1000 will appear ша ы | DURATION OF NOTE" (1 for whole note, 2 for 1/2 note, 4 for
below the listing. Next press SHIFT 5, бел мы M quarter note, 8 for eighth note, etc...)
RUBOUT, 3 and NEWLINE. You have OOS PRINT "(1/":M:")" now duplicated line 1000. Do this for соло LET D (1) = 576/M
everything, and you will save time. 0045 PRINT "PITCH?"; 1 is the highest pitch, 17 is the 1 | After you've typed the program, RUN ооо ІМРЫТ РСТ) 2 PS айын ng it. First it will ask “HOW MANY МОТЕ$?”. nos cL
Here you must enter a number from 1 to ооло NEXT I (Ends loop for inputtting data) 12. More than 12 notes will overload the o500 FOR Е = 4 TO N (Loop for playing tones) memory, causing the program to termin- 0510 LET X = ID (Е) (Sets duration) ate. QTO GO SUB 970 + P (F) s 30 (Plays actual note) The computer will then ask the pitch 0320 NEXT Е (Ends loop) and duration of each tone. When asked 0777 GO та Soo (Repeats series of tones indefinitely) for the duration, type in the reciprocal of 1090 FOR I = 1 TO X (First of a series of 17 FOR...NEXT sub- the actual duration. Forexample:toenter 1010 NEXT I routines that produce 17 different tones. a quarter note, enter 4. One problem arises 1020 RETURN They go from highest in pitch to lowest.
with dotted notes. A dotted eight note 19529 FOR I = 1 ТО X No STOP statement is needed.) counts 3/16, and the reciprocal is 16/3. 1940 NEXT I Since you can't enter this as a numerical 19-0 RETURN | value, you must divide it yourself. Instead 100 FUR I = 1 To X of entering 16/3, enter 5. didis Nis d ы, T
To enter the pitch, type a number e ips TURN | between 1 and 17. 1 represents the highest 1100 s : | = 2 A pitch, and 17 the lowest. | | 10 RETI IRN
After you have entered the tune, the 1170 Fn R I= 1 TO X computer will play the notes in sequence — 4156 NEXT ZEN and then repeat the score continuously. 1140 RETURN You can hear the composition by putting 1150 FoR I = To x be apd. тыы an AM radio on top of the computer, or 1140 NEXT I 3 PRINT "SPEED": vice versa. I found the best signal by putting 1170 RETURN T en ur
Changes For Sound Effector
the computer on top of my stereo. 1120 FOR I = 1 TO X AO LOT JL ER = SPECIA
The changes for two variations arelisted 1190 NEXT 1 below the main program. Thefirstprogram, 1200 RETURN If you want, you can change line 510 to "Sound Effector,” lets you create various 1210 FOR I = 1 Та X LET X=RND(D(F)) to make it sound more arcade type sounds. This is the same аз 1==0 NEXT I interesting. the original program, except for being able 1:20 RETURN to adjust the speed of the oscillations, 1240 FOR I = 1 TŪ X The second program variation, “Compu- thereby creating interesting sound effects. 1450 NEXT I | sition," has the computer do the composing.
1260 RETURN It makes up the pitch, a number between 1
1270 FOR I = 1 TU X 1230 NEXT I L270 RETURN
and 17, and the duration is a random exponent of two.
1300 FOR I = 1 To X Changes For Composition | 1310 NEAT | < 2... 30 LET M = Z ж ж (КМО (6) -1) M 1220 RETLIRN „=, р - pa ` Ж. 1220 FOR I = 1 TU X su PRINT 1:7.) СПИТЕ) » 2 20 LET Р = КАМП (17)
1340 NEXT I
7, 1550: БЕТПЕН 55 PRINT P (1)
| 1 BAD FECR I = i ШЕ X НЕСЕТЕ KT д ke ы y 1270 NEXT I vit S80 RETURN | | 1 i290 EOR 1 = 1 тах Line 30 picks a power of 2 between 0 (1) 1400 NEXT I and 5 (32) 1410 RETURN Thesix can be replaced by any number up
1420 FOR I - 1 TO X to 10. 1430 NEXT 1 1440 RETURN 1450 FOR I = 1 TO X | 14^0 NEXT I
1470 RETURN
1420 FOR I = 1 TO X 1490 NEXT I О 1500 RETURN
35 prints duration and which subroutine was used is printed in line 55.
| |
Line 50 picks a pitch for P(I) from 1 to 17. |
Rich Forsen, 9496 Weston Road, New Hartford, NY 13413.
March/April 1981 35
The Home Computer Market, the ZXSO and the Future
I would like to describe what Sinclair has been doing — what we are doing, and what we plan to do. I would also like to speculate about what Sinclair and other companies in the small computer business might be doing 10-15 years from now. We are still in a very young business, none of us has been around for more than a couple of years, and another 10-15 years is going to make perhaps more difference than any of us realizes.
Sinclair is a company which has been involved in the consumer electronics business (calculators, digital watchs, etc.). When we were designing calculators, particularly programmable and scientific calculators, we'd say, “wouldn’t it be terrific if we could design a computer that wasn't much bigger than a calculator, but would be a real computer, programmable in a high level language." It seemed as though it would be a long time before we could do that when we thought of it in 1973-1974. Technological advances have made it possible much sooner than anyone expected.
We introduced the Sinclair ZX80 in Europe in February 1980, and in the U.S. in August 1980. We've sold a large number of computers. To say that we have been successful is an understatement. We are still growing very rapidly. We've been selling exclusively by mail order and primarily to technically-oriented people. We choose
36
Nigel Searle
erpts c of -. а sp st —! given to the ur Computer Group of New P 1280.
our markets by the type of magazines we advertise in and, although we are beginning to advertise in consumer magazines, most of our sales have come from technically- oriented people. We certainly don't intend that that will always be the case.
The Home Computer Market
We think that our success has proven the home computer market, which people talked about four and five years ago. and which they became diverted from because of the greater profits and the readier market in the small business area—that true consumer market (personal, home, etc. but definitely not small business) — does exist. The sales of our ZX80 have shown that. At the same time that we are not selling a small business computer, neither are we selling a home entertainment computer. The Sinclair ZX80 is not the greatest computer on which to play "Space Invaders." We do have such a software package coming out, but it doesn't have sound or color and its graphics are not high resolution. There are other dis- advantages from the games and entertain- ment point of view which we will come to in a moment.
We are selling a serious computer for use in a particular application. Very often that application is education— the user's own education or his children's education.
We are selling it to individuals who are paying with their own after-tax dollars and not with the tax deductible money of a business. So we have shown, I think, and certainly we have satisfied ourselves, that the personal computer market really does exist and there is no reason to believe that it won't go on growing. We are, of course, doing some of the things which we believe will help it to grow.
Perhaps the most amazing thing about our success so far —and we have sold literally tens of thousands of units, in excess of 50.000 units world wide —is that this unit has an integer-only Basic, has just 1K bytes of RAM, has virtually no application software, and has no off-the-shelf peripherals as of today. Obviously we expect the market to grow as we provide those things. The highest priorities on our own list, i.e., items that will be manufactured by Sinclair, are a 16K RAM module, which comes in a small case about 2.5" square and plugs in to the back of the main board through an edge connector.
Our next add-on option for the unit will be an 8K extended Basic, which will no longer be integer, but will be a fully floating- point Basic with multi-dimensional arrays, powerful string handling capabilities and a whole host of other features. I dont think it is an exaggeration to say that just as our 4K integer Basic is considerably more powerful than Radio Shack's Level I
SYNC Magazine
Basic, so our 8K Basic will be considerably more powerful than Radio Shack's Level II Basic and, indeed, more powerful than Microsoft's 8K Basic. We are also working hard to produce exciting applications software.
Consider VisiCalc. It stands almost all alone as a software package, it is so good that people buy computers just to use VisiCalc and never use their computer for anything else. It may be that VisiCalc is the only software package that justifies the $1000-$2000 expenditure to buy an Apple, Atari, Commodore or whatever.
We envisage that there will be a lot of software packages that are to the ZX80 what VisiCalc has been to those larger computers. Our software packages will certainly be very powerful, but it doesn't take as much to persuade someone that it is worth going out and spending a couple of hundred dollars to be able to use a particular package. We have some software packages, which are scheduled to be released soon that I think are going to be as well known a year from now as VisiCalc is.
Not only has Sinclair satisfied itself that there exists a huge consumer market, but other people also have been persuaded that there is a large market. Consequently, Sinclair is not the only company that is working to support the basic product. In addition support provided by publications such as SYNC magazine, there are at least three independent companies that are far advanced in their plans to manufacture and market hardware and peripherals for the ZX80, including a general purpose interface which will include ап RS-232 and also support disk drives. There are numerous companies developing software and printed materials. Image Computer Products is the semi-official software supplier in the U.S. for the ZX80. While most of the programs in their current catalog, because they are designed to run on the basic 1K machine, are certainly no great advance on anything you have seen before, Image is working hard on more advanced, complex programs which will be available as soon as the larger memory and extended Basic are available.
March/April 1981
ZX80 Features
Some of the features of our machine that make it appealing to the first time user include the following:
Any line of Basic or command at the system level that you enter to the machine will appear at the bottom of the screen. When you enter a line into the program it will go to the top of the screen. The cursor originally appears as a "K." for "keyword." a Basic command word. As long as you only enter digits they will be entered and the cursor will move along and remain in the “К” mode. As long as the cursor is in the "K" mode you can enter at asingle key stroke any of the Basic command words that are available. It will be entered and appear in its full format as a result of a single key stroke. So without the use of a shift key or anything else you can hit a single key and get "SPACE PRINT
This feature eliminates a great deal of typing and is extremely convenient when you get used to it. More importantly, the ease of input is mirrored by the simplicity and economy of storage, because the seven characters involved in "SPACE PRINT SPACE" are stored internally as a single byte. Offering a machine with only 1K bytes of user memory, we had to,be very mean in our use of memory and thus we have employed a number of tricks, or data compression techniques, to minimize the amount of memory the program storage takes.
The 1К bytes of user memory are dynamically allocated between program storage, working space and display. There is no separate video circuitry in the machine. As you get close to your memory limit with a program being stored, you have a decreasing amount of memory available for the storage of the information which is to be displayed to the screen. You then have tolook at the results of your program in chunks. It will display as much as it can —usually a full screen, but sometimes 3/4 full—and then you have to continue execution to see the remaining results. Obviously with a 16K memory it is going to be relatively rare that you would run into that constraint. The boundaries in the memory are not fixed; there is no memory mapping.
If you enter a character such as + (plus) and say PRINT +, the machine recognizes
that that is syntactically incorrect. That is not a meaningful statement in the Basic language. There is no way that a PRINT -Fcan ever be continued in such a way as make it a statement, therefore the machine, indicates with the symbol ''S" a syntax error. By its position it tells you where the error is located and, thus you must make a change at the point indicated before the line will be accepted into a program.
If you are a beginner learning to program, you won't have the frustration of entering a large program only to find at run time that you have put a comma at every place you wanted a semi-colon or that you misused some other feature of the language. You will be made aware of any syntax error in your program before you can complete that line of the program.
One of the disadvantages of the machine which makes it unsuited for games appli- cations is that the microprocessor drives the display. Consequently, when it is computing it isn't displaying and when it is displaying it isn't computing. When you tell it to EXECUTE a program, it goes ahead and EXECUTES the program and
when it is finished it displays the results. It tells you at the bottom where the execution terminated and what the termination condition was. Because we never allow a program to be entered with syntax errors in it, the termination errors are few.
After manufacturing was started, some of our workers decided to make the ZX80 compute and display at the same time. They were successful, and there will in some future version of the ZX80 be the facility to compute and display. Some people have already written machine code routines which enable the existing machine to display and compute. It is programmable in Z80 machine code but there is not an assembler available at the present time. There are PEEK and POKE commands and you must enter the machine code instructions one ata time with a POKE command. You сап then call and execute them with a USR command.
Future Speculations
I would like to take the opportunity now to speculate. I am going to present some fantasy rather than fact, but I believe
37
Computer Market, continued...
that it is in the nature of most science fiction — fiction that will come true.
I think we are going to see the develop- ment of at least three different types of what have hitherto been known as personal computers, to serve the needs of three distinct markets. One of those markets will be the small business market; one will be the educational market; and the third (of which the ZX80 is perhaps the first) will be a market for truly personal consumer- oriented computers.
Within each of these markets, let's consider three elements of computer system design. In particular, what will be the primary means of input to a personal computer? What will be the primary method of data and program storage? What will be the primary means of output?
Future Types of Input
Each of the three markets— business, education and personal—have different needs in each of those areas. If one allows one's imagination to run wild it would seem that the most convenient method of input for a personal computer would be to communicate with it the way we com- municate with anything else that we think is intelligent, the way we communicate with other human beings. That is, we should be able to speak to it and have it understand us in a fairly free format manner.
Obviously, a lot of people have thought about that and some people have done something about it. In fact, one company sells a voice input peripheral for less than $120 and is going make a version of it for the ZX80. At this stage, it’s capability is limited to a small number of commands that you have to speak fairly consistently in order that it will understand. I have no doubt that speech input will be the primary method, if not in the next 10 years then in the decade following, for the personal/ consumer computer.
When you come to the business com- puter, I think the keyboard is going to remain the dominant method of entry. Business has a huge pool of people who are used to using keyboards, who can use them very effectively, and will continue to do so. The typical business executive is
38
not going to be interested in learning to use a keyboard any more than he or she has been interested in learning how to use a typewriter, a copying machine, or any other piece of equipment in his or her office. The business executive is not even going to be interested in learning how to talk toit. It will always be easier for him to buzz his or her secretary on the intercom and say "Do this or that on your computer or computer terminal." It is going to be easier for him or her to get something done than to do it for himself. Consequently, I think the primary method of input for small computers in business is going to be via a typewriter keyboard by exactly the same people who use keyboards now in business.
On the other hand, the educational market has, at a certain level, a requirement for input that isn't served by either voice or keyboard input. I’m thinking of the young child for whom I think the personal computer is going to be a large part of his or her life and education. Clearly that child is not going to be able to use a keyboard with facility, nor is the child readily going to be able to learn to speak to the computer ina way that the computer will understand. In fact, one reason that child will use the computer for education is that he or she cannot do those things with facility. I think the primary method of input for the home education market is going to be a touch sensitive screen.
So we have for the three main market areas three methods of input: speech for the consumer computer, keyboard for the business computer and touch video for the educational market. I don't want to suggest that these are the only methods of input that are going to exist or that they are the only ones that are going to exist in those markets, but I think they are the primary ones.
Memory and Data Storage
Just as we have found out that the disk is more convenient than cassettes, I think we will find that bubble memory or some- thing of equivalent capacity, convenience, speed and low potential cost will be far superior to any medium such as disk, stringy floppy or cassette where you have one device that reads and writes the data and another medium on which you store the
data. For both the consumer and business markets, I feel the primary method of data storage is going to be bubble memory or its equivalent if it is overtaken by some other technology with similar but improved characteristics. |
In the educational market there may be a need for something that will look very much like a video disk. There seems to be a demand for a large quantity of data in excess of what can be stored within any affordable amount of bubble memory. The same programs which teach a child a given discipline in 1990 will probably be perfectly adequate in 1995. So there is a demand for a huge amount of data that does not change. I think that the video disk or something very similar to it is going to meet that need.
In the business and consumer markets there will be a heavy dependence upon remote data banks, with software programs and data being down loaded from a larger system at high speed over a telephone line. I foresee problems with being in constant communication with a remote data bank, but I feel the down-load mode is going to be extremely important. It also solves what otherwise will become a major problem of piracy of both software and data. It will be cheaper for a one-time download than to make a copy and have a means of storing that data or software.
Output in the Future
For the consumer computer I have no doubt that the primary form of output is going to be video. It has the huge advantage that most of us can and still will be able in 20-30 years time to read. We can take ina lot of data at once, far more than we can hear. We can see far more at a glance on a screen. The screen need not be large as long as the resolution is there, a screen of 2"diagonalis more than sufficient to present the information that most of us would require. We can look at a 2" screen with sufficient resolution and see what we want as readily as we can look at a 2”photograph or read that area on the page of a telephone book.
In the educational area video is not so useful. Although I have suggested a touch sensitive screen, probably more important to the educational market for the child is sound output. A child will respond to sound
SYNC Magazine
better than to video. It will capture his attention when his attention might have wandered from the screen. It will convey information to the child which cannot be given visually because the child can under- stand the spoken word but can't read with great facility. Indeed the computer might be doing the job of teaching the child to read.
In the business market, I forsee primarily printed output. Again, there will be a screen on the small business computer or office terminal. But for the same reasons I cited before, when a business executive wants to see last week's or yesterday's or the last hour's sales figures, he or she will push a button and say, "Get me the sales figures." The screen and the keyboard will be outside the executive's office. Somebody will key in the information necessary to get the required data, and that data will come out on a sheet of paper, which can be handed to the boss. That is the way business executives deal with information —on paper. I think there will be a major problem getting them to deal with it on a screen.
That is not vastly different from the way in which computers are being used today in schools, although the system I am speaking about will be widely used in homes. How- ever, while I say the system will not look that much different from the ones in use today, it will be vastly more powerful and less expensive.
Itisin the personal area, in which I have suggested that the ZX80 may be the first computer, that I see the greatest change. І have suggested that the computer will have speech input and video output, for which а 2-3” diagonal screen will be quite sufficient. The memory will be of a bubble type that will be extremely compact and in which we will see the same type of advances that we have seen in semi-conductor memory over the last 15-20 years. The only other thing that will be needed is some means of connecting this computer to a telephone line so that you will be able to get data down-loaded from a large computer. Just as calculators took 10 years to get to their present size, so personal computers will be the size of the calculators of 10 years ago. And they will incredibly inexpensive.
In the business market I see something that is going to be operated by the people who today operate typewriters. It will look exactly like a typewriter with the addition of a screen. It is going to look like one of today's word processors. It will have a keyboard to key in information and a very extensive solid state memory of its own. It will be connected remotely to larger computers and will have printed paper output. It will also have a screen for editing, word processing etc., but that will not be the primary method of output. Strangely enough, I don't see, in the one area that has already adopted small computers, a great deal of change.
In Summary
In education, I see a computer with a screen that will serve as an input device almost as much as an output device with a heavy dependence on sound output. It will probably have some voice input, depending on the age of the child and, in many instances something equivalent to a video disk that has the lessons—in David АҺ words, the “courseware” —on the disk.
March/April 1981
Ubiquitous and Essential
However, what will be expensive is the capability to utilize the power that will be put in your hands, and I think that will create a major social change. Not because there will one group of people who can afford the "credit card computer" and another group that can't: the question is who will choose to use it? Who will have the imagination and the basic education to use it? Maybe with the use of computers in education everybody will, but initially I think there will be a two groups of people that have been described by someone else in contrast to the haves and the have nots. These will be the “knows” and the "know nots." There will be some people who will know how to gain access to and manipulate for their own advantage just about any piece of information they can possibly wish to have. The "credit card computer" will revolutionize the way you do your job and the way you live your life. This card will replace all the others. It will be your electronic funds transfer card; it will be your personal ID; it will be everything. It will be so important to you that if you use
it and integrate it into your life, you would no more go out of your house or indeed be anywhere in your house without your card, than you would without your clothes. About the only place you won't have it with you is in the shower.
I hesitate, but only momentarily, to go one step further and suggest that instead of looking 15 years ahead we double the period and look 30 years ahead. You may have the opportunity in 30-40 years time literally to insure that you will no go anywhere without your computer because it will be inside your body. Of course that will require that it be interfaced with your brain so that all you have to do is think that you would like to know the contents of page 73, volume 21, of The Encyclopedia Britannica, and no sooner will you have thought it than you will see it. That I believe is not impossible. I am not sure that it isn’t dangerous. I know what is dangerous, and that is to think that it is not possible, if indeed it is going to happen. That is really dangerous. So whether we like it or not, whether we are scared by it
or not, it is something that we need to
think about. O
Blank Cassettes
The quality of cassette tape used to save and load programs is an important factor in getting the programs to run. Tape quality for computers is measured differently from quality for audio tape. The tape must be capable of sending to the computer the electronic signals of the program without transmitting extra- neous noises that could interfere with the ability of the computer to load the tape.
Our blank cassettes are tested and recommended for computer use. C-10 cassette, 5 min. per side, blank label on each side in a Norelco hard plastic box. [0010] $1.25 each.
Head Cleaner
After hours of use, the read/write head in a cassette recorder will pick up minute particles of tape oxide. This dirt will hardly be noticable in dictation or music. But it is very noticable in computer use. One dropped bit in 16,000, and the program won't load.
Help keep your recorder in top shape with our non-abrasive head cleaner. It consists of 18 inches of stiff cleansing fabric in a standard cassette sheii. One 10-second pass every 40 hours of use will keep your heads as good as new. [0011] $2.00. Send pay- ment plus $1.00 Shipping per order to:
Peripherals Plus
39 East Hanover Avenue Morris Plains, NJ 07950
39
puzzles S problems
“1, Merlin, challenge the readers of SYNC to a battle of wits. Every issue I shall propound a series of problems for you to solve. They will vary in complexity and category and should prove an interesting diversion between articles. I also welcome contributions from our readers. If you have a favorite puzzle you feel will be of interest to us send it in. If I use it I shall send you a copy of one of my famous MERLIN'S PUZZLER books.
“And now to work! Our first puzzle is called...
THE — JACK PUZZLE
his is a great old puzzle. Draw upa М rough board like the one shown at УЙ ( the right. Place a checker in every || square that has a letter in it. Your ШІ problem is, starting with the | checker in the square marked “1”, to remove all of the checkers from the board, save one, and have this last checker end up where you started in square one. You can jump one checker over another checker in any direction, side- ways, up and down, or diagonally. Whenever you jump over a checker you must remove it from the board. However, as in checkers, the square beyond the checker you are jumping over must be empty. A continuous series of jumps, using one checker, will be considered to be one move. You must solve the puzzle in just four moves. On your mark, get set, start jumping!
ээ
THE BARREL PUZZLE
OW, this puzzle should prove to be “barrels of fun” for all of you! Printed on the three barrels pictured below are the numbers “1,” *6" and “3.” Can you rearrange these barrels so that you have a 3 digit number that can be evenly divided by seven? The answer is quite
ingenious. | 1) (9) (5)
THE GOLDEN HELMET PROBLEM
he management at the Peabody Helmet Company / discovered that one of the ten artisans that make their / line of solid gold helmets has been cheating them. It has been determined that one of the men has been using one ounce less gold per helmet than required, and, he has been keeping this ounce of gold for his own use. Mr. Peabody, a man who is always in a hurry, has decided that he can determine who the thief is with just one weighing on the large company scales. One thing should be pointed out, each artisan stamps his initials inside each helmet that he crafts. Now, how
THE DOUBLE HORNED ZAT PUZZLE
could he find out, with just one weighing, who the guilty party is? Y ur last puzzle comes from the book "Merlin's Puzzler 2" and is called The (e) Double Horned Zat Puzzle. (See the drawing at the left). Merlin claimed that C ре is a very powerful magical sign and is useful in warding off pests, the humors, and bill collectors. To generate the maximum amount of magical power you must draw the sign using one continuous line. Also, no part of the line may cross over any other part of the line. Now, practice well, you never know when a good hex sign will be needed.
Answers on page 44. I hope that you enjoyed Merlin’s puzzles. Now. don't forget, if Your editor,
you would like to try and stump our readers with one of your own p ptt puzzles, just send it along. If Merlin uses it he will send you a copy of ZZ А Ж bu one of his books that deal with puzzles, games and magic. So long until next time... Charles Barry Townsend
40 SYNC Magazine
Problems for Computer Solution
Here are 90 problems with a thorough discussion and references for each. Eleven types of problems are included, for example, arithmetic, algebra, geo- metry, number theory, probability and science. Even includes three classic unsolved problems and seven appen- dices. 104 pages softbound, $4.95 [9Z].
The teacher's edition contains solu- tions with complete listing in Basic, sample run and in-depth analysis ex- plaining the algorithms апа theory involved. 280 pp softbound, $9.95 [9Y].
Katie and the Computer
Fred D'Ignazio and Stan Gilliam. This is a delightful story told in words and full color drawings of Katie's adventures when she "falls" into a computer. In Katie's journey through the land of Cybernia she meets the Software Colo- nel, the Bytes, the Table Manager and even a ferocious Program Bug. Her journey parallels the path of a simple command through he stages of pro- cessing in a computer, thus explaining the fundamentals of computer operation to 4-10 year olds. Supplemental explan- atory information is contained in the front and back end papers. 42 pp. hardbound $6.95. (12A)
LN
Have You Been
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Edited by David H. Ahl. The best col- lection of computer cartoons ever is now in its second printing. There are fifteen chapters of several hundred cartoons about robots, computer dating, computers in the office, and much more. Keep the book with your reference works. When needed, the right cartoon can say it all for you. Pro- vides hours of fun and comic insight. 120 pp. 8'5 x 11" softbound. (6G) $4.95.
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The book includes many activities that don't require a computer. And if you're considering expanding your com- puter facilities you'll find the section on how to select a computer complete with a microcomputer comparison chart inval- uable.
Much of the material has appeared in Creative Computing but the back issues are no longer available. Hence this is your only source to this practical and valuable material. Edited оу David H. Ahl,this mammoth 224-page softbound book costs only $15.95. (The individual issues, if thev were available, would cost over $60.00). [120]
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Reviews
Jonathan A. Stein
7Х80 Programs
ZX8&0 Programs, Volume 1 edited by Chris Denning; published by Zipprint, 418 Poole Road, Parkstone, Poole, Dorset BH12 1DF, England. 82 pages, paperback. £5.25 in the U.K.; $13.00 in the United States.
Although intended for all ZX80 users, this book is aimed especially at people wih little prior computer experience. The book contains twenty programs, of which nine are "practical" programs for business and home, three are for educational purposes, and eight are games.
Stock List, one of the utility programs, is intended for keeping an inventory of your stocks. Although the program will only hold thirty entries, this problem can be bypassed by storing several copies on cassettes.
The next utility program, Wavelength/ Frequency Conversion, converts wave- length measurements from kiloherz to meters, and vice versa. This function may be useful for people in The United Kingdom to convert radio station dial locations from meters to kiloherz, in which imported radios are calibrated.
The VAT Calculator program was intended to calculate the 15% sales tax found in The United Kingdom, although any tax rate may be entered. This program determines the amount of tax paid, when only the final total is known; it does not calculate the tax to be paid on the original purchase price.
The educational programs are Basic Maths (Add/Subtract) and Basic Maths
(Mulitiply/Divide). Both present drill and practice excercises, offering three levels of difficulty, as well as *emergency" features which provide the answer if the student cannot solve the problem. The two math programs share many of the same lines, making it possible to avoid much of the tedious process if the first program has already been saved.
Prime Number Tester,is an educational tool to allow to the user to determine whether or not a number is prime.
The game, Brain Teaser, is a pattern matching game, similar to the hand held electronic games, Simon or Einstein, in which the player must duplicate a pattern. In Brain Teaser the pattern is a series of twenty numbers, presented individually, with two levels of difficulty. When the game is concluded, either by an incorrect entry, or by successfully duplicating the series, the program posts the score out of the possible twenty correct turns.
The next program, One Arm Bandit simulates the operation of a slot machine. For each turn the player is charged 5p, and may win from 10p to 70p depending on his luck. By changing lines 90 through 120, the program may be altered to suit other forms of currency.
Some of the utility and educational programs in ZX 80 Programs, Volume 1 are worth while and several of the game programs are quite good. Unfortunately, the typewritten copy and hand scrawled programs make it difficult to read. Г]
ZX80 Pocket Book
The ZX80 Pocket Book) by Trevor Toms; Phipps Associates, 3 Downs Avenue, Epsom, Surrey. KT18 5HQ, England. 109 pages, spiral bound. 4.95.
The ZX80 Pocket Book differs from other books about the ZX80 because it is aimed at the experienced programmer.
The book begins with a review of the Sinclair Basic, which unlike the sections in other ZX80 books, merely highlights this material from the original manual, instead of repeating it at length.
The section on programming is parti- cularly valuable because it offers simple tips on how to become a better program- mer, as well as suggestions on how to better use many Z X80 features. This sec- tion is not a how-to programming manual, but is a well presented chapter on improving programming technique.
The chapter, "Program Storage and Retrieval," offers useful instructions on how to safely save programs on cassette. The tips presented are both those of the author and Sinclair.
Section 5, "Data File Storage and Retrieval,” discusses how to preserve both data and programs without using the DATA statment present in other Basics. The authors suggest saving impor- tant files in triplicate to ensure that the information will not be accidentally erased.
The ZX80 Pocket Book also contains thirteen programs, including a Machine Code Conversion and a Share Valuation program which keeps track of shares of stock and the price at which they were purchased. This latter program requires 3K of RAM.
The final full section of the book pre- sents all the ZX80 Basic commands and explains how they are used. Examples are offered, so one may easily see what these commands are intended to do.
The ZX80 Pocket Book ends with five appendices for the instruction set, the ZX80 Character set, graphics, error codes, and a command summary.
Phipps Associates has succeeded in giving the ZX80 community a useful, attractive volume at a moderate price. (0
SYNC Magazine
The ZX80 Magic Book—A Review
Jonathan A. Stein
The ZX-80 Magic Book is published by Timedata Limited, 57 Swallowdale, Basildon, Essex, England. 60 pages, soft- bound, £4.75. |
This book offers both programs and instructions on how to make better use of this popular computer. The second half of the book contains material which helps one to understand how the ZX-80 works.
The text explains how to create and debug programs, how to convert from other Basics, and includes such informa- tion as instructions for improving the television picture, how to connect a video monitor in place of a television set, and other useful technical information.
The twenty-one programs include Russian Roulette, which I hope no one takes too seriously; Moon Lander, a ver- sion of Lunar Lander, which is quite a difficult game; and a 2K version of Hammurabi, which is one of the best ZX- 80 games I have played. This well known computer game was the subject of the SYNC Challenge last issue. As the ruler of ancient Sumeria, you must make all vital decisions on how to run the city, such as: how much grain is allocated for food and seed, how much land is traded for grain, and vice versa. On each turn you are told how much land and grain the city has and how the population fared from your previous decisions. If you calculate carefully, the population increases, and the area of the city grows. If not, people starve and the city loses land.
The other games are a mixed lot — some good, some not as good. A few non- game programs are also included such as Sums Tester and More Sums. The ZX- 80 Magic Book should be a useful addi- tion to most ZX-80 libraries, particularly for its technical sections. О
í T
ZN
March/April 1981
А Review
and Breakout
The shared use of the microprocessor chip in the ZX-80 for computation and screen display makes continuous graphics difficult. The screen flashes whenever you input information, an effect that may be considered undesirable in a game.
The Amazing Active Display is a hybrid program containing machine language in a Basic program. The machine language routine allows a continuous display on the screen. In the program, a machine language program, stored as hexadecimal code, is converted into decimal numbers and POKEd into the computer's memory. The machine code includes calls to several ROM routines, but bypasses the blanking of the screen.
This program is intended for use in your own application programs, for uses such as animated graphics, games requiring updates to the screen, instrumentation, and debugging. You can provide a program- mable pause in a Basic program with a screen display.
The Amazing Active Display
Joseph Sutton
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Breakout is a ga rogram using the Amazing Active Display, and shows what can be done with the program. It also comes as a Basic program with the display routine listed as Hex characters.
With real time action and challenge, Breakout is one of the best games yet available for the ZX-80. There is a continu- ous display at the top of the screen of a wall of blocks, and a graphics block bouncing up and down with a smooth continuous motion. The player must move a paddle at the bottom of the screen using the arrow keys (5 and 8). Each time the moving ball hits a block at the top of the screen, that block is removed. If you miss the ball with the paddle, you lose it. Once you manage to clear all the blocks off the screen, the ball bounces aimlessly around. There is no victory routine.
stop the game is to unplug the computer. The Break key does not function. The instructions are quite minimal, and it may be difficult to understand the program well enough to use it in your own pro- grams.
We like both programs, and enjoyed playing with them. The Amazing Active Display ($20/£10) Breakout ($20/£10)
K. MacDonald
26 Spiers Close
Knowle, Solihull West Midlands, B93 9ES Great Britain
Joseph Sutton, 170 S. Hillside Ave., Succasunna,
NJ 07876.
puzzles № problems answers)
The Jumping Jack Puzzle: Jump / over M, N, F, D, C, A, B, G, O, Q, Pand K. Next play L over H. Then play J over E and L. Your last play is I over J. (If you have any trouble following the answer place “letters” оп top of the checkers to make it easier to follow).
44
The Golden Helmet Problem: Mr. Peabody would take | helmet from worker A, 2 helmets from worker В, 3 helmets from worker C, and so on. He would then put all 55 helmets onto the scales. If the total weight of the helmets was 1 ounce less than the weight of 55 helmets should be than worker А would be the guilty party. If the weight was out by 2 ounces then the thief would be worker B, etc.
The Barrel Puzzle: Turn the six upside down. You now have a 9. The number we want is 931.
The Double Horned Zat Puzzle:
SYNC Magazine
The ZX80 Companion —A Review
Jonathan A. Stein
The 27Х80 Companion, by Bob Maunder, Terry Trotter, and Ian Logan; Linsac, 68 Barker Road, Middlebrough TSS 5ES, England, 128 pages, softbound, £10. Available in The United States through Image Computer Products, 615 Academy Drive, Northbrook, Illinois 60062, $19.95.
This book is designed to supplement the original ZX-80 manual. It includes tips on the operation, assembly, and pro- gramming of the ZX80 for maximum effectiveness. Although the original manual is useful, and gives a beginner clear, concise directions on the operation and programming of the computer, The ZXó0 Companion continues beyond the offerings of that manual.
The book is divided into six chapters, and has two appendices. Chapter One, “Operating the Z X80," has five sections, explaining basic operating procedure for The ZX80. This section contains many of the tips contained within the authorized manual, although there are hints not found in the Sinclair booklet.
March/April 1981
The second chapter, entitled “Theory of Computers," is especially useful for computer novices, since it explains what computers do and how they function. This portion of the book also examines computer languages, and the compo- nents of a computer system.
Chapter three, ^ZX80 Basic,” explains the particular language of this computer, and focuses on the individual functions and how they are used. This section includes the sub-headings: Assignments and Calculations, Input and Output, Con- ditional and Unconditional Jumps and Loops, Arrays, Character Handling, and Machine Code.
The fourth chapter, "The 7Х80 Monitor," looks at the monitor, and explains PEEKing. POKEing. and sub- routines. It also contains sub-routine memory maps and monitor maps, as well as a cursor table and a discussion of ZX80 machine language. This portion of the book will be particularly helpful for the serious programmer.
Chapter five offers assistance in con- structing the ZX80 kit, which is available in the UK, although some of the advice may apply to the construction of the MicroAce. The authors have presented some suggestions which augment the factory manual.
The final chapter of The 7Х80 Companion contains programs from the Linsac tape collection. These programs are generally good, with The Maze game being one of my favorites. The Spelling Quiz program will be quite useful as a study aid for small children.
The final pages of the book contain two appendices, which include a compar- ison of Z80 instruction codes and the Z X80 character set, and a preview of the original Sinclair 8K ROM.
The ZX80 Companion will make a use- ful addition to most 7Х80 libraries. There is much helpful and informative material in the volume, although some material covered in the owner's manual is repeated. As useful as it is, the price seems high when one considers the undistinguished printing and binding. 0
45
Disassembled Basic, Linsac, 68 Barker Road, Middlebrough TS5 5ES, England. 48 pages, paperback.
Linsac has published a disassembled listing of the Sinclair Basic. What, you may ask, is a disassembly? Well, wben machine language is placed in memory, either in RAM or ROM, it is stored as numbers. These numbers represent machine-language instructions, called “mneumonics’ since they are abbreviated versions of the command. For example, an increment instruction is represent as INC. When a programmer enters a program using these or op codes, an assembler is used to turn the commands into numbers. A disassembler reverses the process, turning the numbers into lines of code so humans can understand it.
A few lines of disassembled code look like this:
loaded. Loading a register with a value from a memory location requires three bytes, one for the load command and two for the value of the location. The third column is for labels. In this case, the labels used are just the locations of the commands prefaced by an L (labels must start with a letter, though they can contain numbers). There are two uses of labels. First, when assembling the code, you can refer to the label instead of the location. Thus, if you have a segment of code that multiplies two numbers, you could label it MULT. When you wanted to jump to that code, you could say JP (for jump) MULT. When the program is assembled, the correct value for MULT will be inserted.
The other use for labels is to make the code easier to read. When you are scanning a disassembly and see MULT, you know you have found the multiplication routine.
O7BE 2E LO/BE DEL HL. ЖЖІМТЕЕКРБЕТЕКЖЖ
О?ЕҒ 222640 LD (1.4026) „НЫ. SDAVE FROG ADDRESS Q7C2 210000 „р Н, LOOO s ZERO НІ
O7CS OQ NOF + AND “МЕЦ” CODE
O7C& 221240 L.D (1.40190 a HL ; ZERO POINTER
O7C9 211940 LU HL.,L.4019 ;FOINT TO SYNTAX FLAGS O7CC CR6E БІТ a CHL) TEST IMMEDIATE FLAG OZLE 2807 JR Lg lLti7 D7 r JUME IF IMMEDIATE
The first column contains the memory locations of the code. In this example, the code starts at hex address 7BE. The next column shows the hex value or values for the command. Commands require from one to three bytes, depending on how much information is required. For instance, decrementing a register requires only one byte. Loading a single register with a number would require two bytes, one for the command and one for the number to be
46
Unfortunately, the Linsac disassembly doesn’t use this kind of label, making the listing harder to decipher. The label LO7BE tells us that the line is at 7BE, but doesn’t give us any useful information.
The fourth column contains the mneu- monics, followed by any values used by the commands. The final column contains comments, making up in part for the lack of meaningful labels. The comments help, but they are vague in places.
David Lubar
Stepping through the code, the first command decrements a pair of 7-80 regis- ters called H and L. Next, the value in these registers is stored in memory. The HL registers are loaded again, this time with values from another area of memory. The NOP command stands for “no opera- tion.” Possibly, this byte was left open for future changes in the code, or was created by an earlier change in the code. The comment isn’t clear. The next two com- mands again place the register values in memory and reload the registers. The BIT command tests a value stored in location 5 to see whether the command is from a program or from the immediate mode. If the command is immediate, the zero flag is set. The next line jumps to 7D7 if the zero condition is met. Otherwise, the program falls through to the next line (not listed here).
With a disassembled copy of Sinclair Basic in hand, an experienced programmer can work wonders. He can access any of the Basic functions through calls to the monitor, using the USR function. Even more powerful is the potential to use the Basic subroutines from machine language programs. There is no need to write your own PRINT subroutine when you can go through one that already exists in the monitor. In essence, the disassembly puts the full power of Basic at the programmer's disposal, even when he is writing programs in machine language.
The listing comes fully commented, with asterisks marking the function of each subroutine, such as *LIST*, and *PRINT CHARACTER*. As mentioned earlier, there are places where the comments could be clearer. The printout is a Xeroxed copy of a dot-matrix listing, but itis legible. The listing, including a table of referenced lines, is 48 pages long.
Besides being a good tool for program- mers, this book could also be used by someone who is learning Z-80 code. By seeing how the commands are used, and what the results are, you can gain an understanding of this machine language.
SYNC Magazine
This section is intended to preview the peripherals and accessories that will be available for the ZX80. Readers are encour-
Product Preview =
aged to submit reviews of products men- =
tioned here.
CAI Instruments of Midland, Michigan is developing a series of interfaces for the Sinclair ZX80. The company has announced a PC board which will plug into the ZX80 expansion port, in front of the 16K RAM module. This peripheral will work with a printer and includes an improved interface for storing programs on tape. The basic package includes the board, printer and tape recorder, and will sell for approximately $200. Other packages will be available with varying qualities of printers and recorders. One system, containing a printer, the board, and a high quality tape system will cost less than $350. CAI is also working on a full size plug-in keyboard for under $50. The company also has interfaces to work with floppy disks. CAI Instruments, 2559 Arbutus Court, Midland, MI 48640.
NOW APPEARING
Innovision of Los Altos, California is devising an improved graphics device for the ZX80. The company will have a hand printed graphics system using memory mapped video. This peripheral will be available once the 8K ROM is released. Innovision, P.O. Box 1317, Los Altos, CA 94022
Voicetek of Goleta, California has been authorized by Sinclair Reasearch Limited to develop a speech recognition unit. The project has been delayed until the intro- duction of the ZX80 16K RAM. Voicetek, 6690 Abrego, Goleta, CA 93017.
Sinclair Research Limited now expects to have the 8K Basic ROM for the ZX80 available by March 1981. The new Basic
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allows the use of floating point arithmetic to nine digit accuracy, and contains log and trig functions with inverses. This ROM facilitates improved graphics, and contains 37 new functions including DRAW, DATA, ARCSIN, VAL, and SCROLL. The plug- in conversion includes a new keyboard template and a supplementary manual, and should sell for $40. Sinclair Research Ltd., 50 Staniford St., Boston, MA 02114. Sinclair has also officially announced the long-awaited 16K RAM expansion for the ZX80 computer. The module has received FCC certification and is expected before the end of January 1981. The unit is housed in a plastic box the size of two cassette tapes, and plugs into the expansion port at the rear of the computer. Sinclair is now taking orders for the $99.99 RAM.[]
Resources for the ZX80 and MicroAce
In the last issue SYNC presented a list of 24 companies and organizations with products related to the ZX80. Below there is a supplement to the original resource list. If you missed that first issue. send $2.50 or £1.25 to SYNC, and we will gladly send it.
We welcome entries from manufacturers and readers for the resources column. Please include the name of the item, a brief description, price. and complete data on how to obtain it. Send contributions to SYNC Resources, 39 East Hanover Avenue. Morris Plains. New Jersey 07950.
Software
Six programs for the ZX80 — £4.95 U.K. Bramwell Enterprises 87 Anderson Crescent Great Barr. Birmingham B43 7ST England
Graphics for the 1K ZX80 C12 Cassette with four programs : Symmet- rical Patterns. Large Print. Draw a Picture. Plot a Picture Cassette and manual — £ 8.00 Graphics manual only — £ 3.00 Bridge Software 36 Fernwood Marple Bridge Stockport. Ches. SK6 5BE England
Self-Instruction Courses for the ZX80 Cambridge Learning Ltd. Unit SS Rivermill Site Егее Post. St. Ives Huntingdon. Cambs. PE17 BR England
Assorted games packages for the ZX80 4K — £5.95 and — £9.95
Database Consultancy
105 Fairholme Ave.
Gidea Park. Romford
Essex RM2 5UR
England
Assorted software for the ZX80 Kala — £2.75 Hewson Consultants 7 Grahme Close Blewbury. Oxfordshire QX11 9QE England
48
The ZX80 Pocket Book — £ 4.95 U.K. Phipps Associates 3 Downs Avenue Epsom. Surrey KT18 5HQ England
ZX 80 Software: Pointasketch. Nim, Mothership, Pharoah's Tomb. XOX. AddMax. SubMax. MultiMax. DivMax. (decimals-10 digit). Hotel (50 room bookings). Playmath. Biorhythms. Send SASE for detailed list and free pro- gram.
Datalog
20 Aylen Rd.
Portsmouth, England PO3 5HB
England
Z X80 АК Programs: Star Trek. Pontoon. Adventure - £5.95 (£2.45 each)
M. Bates
Dever Barn
Micheldever
Winchester. Hants
England
Cases for ZX80 Systems Phoenix Management Services Paragon House 46 Kent House Lane Beckenham. Kent England
ZX80 Software: Moon Lander. Pontoon. Calendar. Maths test — £ 2 P. Pickering 56 Lennox Road Todmorden. Lancs. OLI4QD England
Software Cassette: Random number guess-
ing, Memory Test, Reaction Speed Game, Hangman — £6.00
Educational Aid Cassette — £ 5.00
Rose Cassettes P.O. Box 28
Solihull. West Midlands B91 3LU England
Tutor programs for ІК and 2K Z X80 IK listing — £ 3.00 ($7.00) 2K listing — £ 5.00 ($12.00) Wyncom 11 Furze Platt Road Maidenhead Berks. SL6 7ND
Hardware
Interfaces and Printers for the 2 Х80. Packages from $200.00
CAI Instruments. Inc.
2559 Arbutus Court
Midland. MI 48640
Sinclair ZX80 sales in New Zealand David Reid Electronics Ltd. C.P.O. Box 2630 Auckland 1 New Zealand
Sinclair Z X80 sales in Canada Future Distributors. Inc. 1189 Phillips Square Montreal. Canada H3B 3C9
Gladstone Electronics 1736 Avenue Road Toronto. Ontario M5M 3Y7
Full-size keyboard for MicroAce Fully wired — $85.00 Kit — $65.00
Leonard Holmberg
P.O. Box 6273
Orange. CA 92667
RF shielding kit for MicroAce — $3.00 Outbound Engineering Р.О. Box 218 Сһап ет. ТХ 75758
Users Groups
Publishes club newsletter. Send self- addressed. stamped envelope for free copy.
National ZX80 Users Club
Unit 3
33 Woodthorpe Road
Ashford
Middlesex TW15 2RP
England
SYNC Magazine
David Ahl, Founder and Publisher of Creative Computing
You might think the term "creative com- puting” is a contradiction. How can some- thing as precise and logical as electronic computing possibly be creative? We think it can be. Consider the way computers are being used to create special effects in movies—image generation, coloring and computer-driven cameras and props. Oran electronic ‘“sketchpad” for your home computer that adds animation, coloring and shading at