MAY/JUNE ’85 - $3.00





2068 is COMING BACK!





Above shows fully PoPulated BUFFERED BUSS EXPAHSIONM BORED and Rx-S1 PARALLEL I-0 BORRED Plugged into TS1@68 with 16K RAM. 3 volt 3 amP regulator CtoP rights, bufferdecoder Ile Cacross toro. six exPansion cannector Points across bottoms with Fe-ol I“ board Plugged into exPansion Point second from left.

BUFFERED BUSS EXPAHSIOH BORED - & 3°86" « 8 14" double sided Plated thru holes-Parts list“documentation-9S8 desree connector. For 2RSG, 2HB1, T1680 & TS1i50G. Versions available: "EXP-1? Bare board version 465 “EXP -1A’ Fully FoPulated kit ; te "ERP-1B’ Economy kit $62 Cadd EXP-1F and EXP-1C later for a fully PoPulated boards “EMP-1R° S volt-3 ame regulator kitcuse with EXP-1B or EXP-1> $7

gs ES mies 3 Oe Extra cannectore use with EXP-1B or EXPL 2 $11

RHM-81 Parallel IO board - 2 3¢8" « 3" double sided-Plated thru holes“Parts list‘documentation. For 2886, 2Xe1. TS14@8. TSis0@ & TSs28e8, Versions available: . : "RH-81° Bare board 1 "RX-G1A’ Fully PoPulated kit. $25 CPluas into comPuter’s rear exPansion slot > *RH-SIE’ Fully PoPulated kit, miftus connector . $21 (Plugs into BUFFERED BUSS EXPAMSIOM BORRD » = *Rie-S1iC’ Demo“test kit | $f (LED array and DIP switch for outPut and inPut deémo-t Order ty alpha-numeric abbreviation (i.e. “EXP-1B°’o, Posta handling to U.S. and Canada included. Overseas add 18%. Sen check om money arder (U.S. dollares? allow check clearanc


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ICR Designs

pant RAN | BEN MR! MAY/JUNE ’85

VOL.1 NO.4 Publ ished by:


i 29722 Hult Rd.

4 Colton, Oregon 97017 (503) 824-2658


Editor: Tim Woods 7 Assistant Editor: Stephanie Woods Photography and Production: Tom Judd Consultant: M.J. Marsh Contributors In this issue: Bruce C. Taylor John McMichael Edwin S. Salter i Dick F. Wagner Bill Gunter Dennis Jurries William D. Erickson Paul T. Erickson Tim Woods Tom Judd Printed by: Toad'L Litho Printing and Composition, Oregon City, OR

NOP) SMR ti saree,

Bate Reem)

2 Time Designs Magazine is published bi- monthly and is copyrighted © 1985 by the Time Designs Magazine Company. Reproduction of this magazine In whole or in part by any means without written permission is prohibited by law. Subscriptions: $15 for one year (six issues) in U.S. funds only. 3rd class

j bulk rate postage is paid for by T.D.M.C.

j , , permit no. 51, Colton, Oregon.


Baitor Ss. COTne?s. « oaseoas Letters To The Editor.. Bits And Pieces ¢ «2-40 +e at eee

SPECIAL REPORT: 2068 Is Returning To The U.S

Introduction To Computer Control.. Machine Code Joystick Routine..... Z0GS .COLST - Gs 5 tse Ce & 6s 30-2

A Graphics Problem For The T/S 2068. 2068 Program: Slot Machine. «sass ss VAMP TV To Monitor Kit...

Tasword: TWO> Ti DB w<. dees 4 60S se Hes PRO/FILE 2068....

Coupon Magic....

Tie. Dealer “4 Deis oxi « eee st ess Damco/Rotronics Wafadrive Reviewed. TS: 2068/Spectrum-Wares., « «0544 ss» 2

The Shopping Mart...... eee rT

The intel !igent computer- controlled droid on this issue's cover was designed

on the Cover: and drawn by Debbie Woods, an artist from San Jose, California.

I recently returned from a trip to California. Sinclair con- puting is alive and well in that large west coast state, and I was able to visit with some interesting T/S enthusiasts (in-person and a few on the phone). Jerry Chamkif, president of Aerco im Austin, Texas was also in California on business (and vacation) at the same time as I was, but unfortunately our paths never crossed. Jerry demonstrated his new 2068 Disc System at the San Francisco Users Group meeting. There were some problems with the disk software and the system crashed a few times. This has been corrected with some help from Jack Dohany of Menlo Park, CA. Aerco started shipping Disc Systems and Interfaces: on- Apri 72.

My first stop was Sunset Elec- tronics down by the waterfront in San Francisco, to meet with owner and proprietor John Warburton. This 1s one of the few.adctual stores in the U.S. that deal in Timex Computer Equipment and Accessories. I even found Time Designs Magazine on the book rack there. Sunset Electronics also does a large mail order business (32 page catalog available upon re- quest. Writs to: -2254 Tereyal Sires San Francisco, CA, 94116). John end some other T/S users in the Bay Area were preparing for the annual West Coast Computer Faire on March 30- April 2. Arrangements had been made with Sinclair to show a QL there.

Down the Peninsula a few miles, in the Silicon Valley I found the manufacturing and operating facility of A & J Micro Drive. Jim Howell is the ''man-in-charge" here, and they have recently introduced a stringy- floppy system for the -stock T/S 2068. Along with Jim, there are 10 other employees who assemble and test the drives and wafers. A & J's biggest business is drives and interfaces for various models of electronic

—\ Editors Corner

typewriters on the market. While I was. there, Jim told me that he had purchased the rights and equipment of the wafer technology used in the T/S 1000 Micro Drive from Entrepo (the inventors). A § J will now incorporate the model 1000 Style wafers (version 0) and drives into the model 2000 for the T/S 2068. The original model 2000 used a different wafer (version 2) and are not compatible with the new units being shipped. On the outside the model 2000 Micro Drive will remain the same.

Before heading south, I chatted on the phone with Bob Orrfelt of Redwood City, CA and also Rita Cary . who is the chairperson of the Silicon Valley T/S Users Group. Bob Orrfelt has his own cottage industry and offers a 64 Col. Word Processor for the 2068, and some nifty new EPROM Cartridge Boards. Among some other things he has been working on is fixing up the "bugs" in the 2068's ROM. Bob may be contributing some information for Time Designs readers in an upcoming issue.

Down in Los Angeles, home of congested freeways, smog and Mickey Mouse...I met with Sinclair computer expert. Dave Clifford. Dave:wrote a review in our last issue on the Z- Link interface card. He is also very knowledgeable on telecommunications using the Westridge 2050 Modem and MTERM II Software. Dave demonsrated his Sinclair Microdrives on the 2068 for me. They are very compact little units, but also very fast!

Well here we are back "home". And before closing, I want to say thank you to all of you who have mentioned or shown your copy of Time Designs to other T/S users. It is appreciated and benefits us all. Not only does it increase our circulation, but it will also enable us to add more pages and articles to the mag- azine for you.

See you next issue! Tim Woods/Editor

An unidentified employee assembles Model 2000 Microdrive units for the Timex 2068. Circuit boards and ribbon cables are shown on the left.

Jim Howell in his office at A & J Microdrive in Sunnyvale, California.

Send your corre- spondence to: Time Designs Magazine, C/O The Editor, 29722 Hult Rd., Colton, OR 97017.

letters to the editor

Dear Tim,

Yesterday, as one of the guest speakers at the bi-monthly meeting of the West Los Angeles ZX81 Users Group, I received a complimentary copy of the March/April '85 issue of Time Designs through the co- operation of Ed Gray.

What a nice job you're doing! I found your magazine contained lots of useful material, was clearly printed, and reasonably free of typos. The reproduction of LISTings, photos and graphics was particularly good compared to most other Timex/ Sinclair publications (mostly news- letters).

My personal involvement in the Sinclair/Timex world has been min- imal since I completed my Howard W. Sams book on the 2068 almost two years ago ("'TIMEX SINCLAIR 2068 BEGINNER/INTERMEDIATE GUIDE"). I've Since written three other books- the "awful" ADAM, the "spectacular" Sanyo MBC 550 Series, and the "rot- ten" Apple //c. (Those quotes rep- resent my one-word reaction to the computer.

However, your readers might be interested that last December I got the loan of an English Sin- clair QL for a month, and did an over-7000 word detailed review for MODERN ELECTRONICS (76 North Broad- way, Hicksville, NY 11801, $12.97 for 12 monthly issues). This slick new magazine (8 issues so far) is

about 100 pages per issue, and

covers the whole field of electronics for hobbyists and experimenters, with considerable computer coverage. They have scheduled the QL as the cover story of the June issue, which comes out in May, pending FCC approval of the U.S. QL (which is expected anv

Sincerely, Fred Blechman Canoga Park, CA

(EDITOR- Thank you very much Fred for the nice compliments about TIME DESIGNS. We keep trying. Our readers, T am sure were interested in hearing what you were up to Lately. Many of them have your Howard W. Sams book on the T/S 2668. Also, I would Like to mention to our readers that you have agreed to contribute some info on the QL ina future issue of TINE DESIGNS, )


Thanks for your copy of VOL 1, NO 3. Very well Executed! Being a ZX81 owner, I do hope you will not forget us,


L. Chavarie Ottawa, Ontario Canada

(EDITOR- We certainly won't forget you. ZX8J] users have received a Lot Of crrticsm in the past, but Bruce C. Taylor's anticke on computer contrack in this issue, affinams what avery powerful Little computer «t 45. We wih give you more programs and anticles in the future.)



Sinclair of the U.K. has just recently returned from a couple of electronics in- dustry trade shows in the Soviet Union.

The Kremlin is trying to upgrade their culture and education system with micro- computers similar to what one might see in

a typical American elementary school class- room. The iron curtain hi-tech industry is years behind other parts of the world as far as mass production. Existing microcomputers in the Soviet Union consist of poor copies of the Apple II. Sinclair demonstrated their Spectrum Plus and QL to the eager Soviets.

I wonder what they thought of “one stroke keyword commands?"

Sinclair has ceased production of the original ZX Spectrum (16k and 48k versions), and is marketing exclusively the Spectrum Plus. This computer is styled after their top-of-the-line QL. Has an improved keyboard and 48k RAM.

Speaking of the QL, Mary Reinman of Sinclair (U.S.) could not give us word of it's release as we went to press. The comment was made that FCC approval was just "a couple of weeks" away. Some experts here and abroad, claim that FCC has already approved the com- puter, and that Sinclair is waiting for units to ship before they announce avail- ability.

One U.S. vendor that is patiently waiting for the release of the QL, is Curry Computer (5344 W. Banff, Glendale, AZ 85306). They have stocked a large quantity of QL software and books. They also publish a news- letter called "The QL Report". In the April '85 issue that we received, there was a sample of a QL screen display from a program called "GRAPHIQL". Very impressive.

The English computer press has not always been very kind towards the QL, and on more than one occasion remarked about it's rather "slow" operating system. How- ever, the few individuals here in the U.S. that are fortunate to own the British QL, are very pleased with the computer and speak very favorably of it. We have yet to see what changes Sinclair made on the machine to bring it to America.



The Weymil Corp. (Box 5904, Bellingham, WA 98227-5904) has a software package called MINI XMOD 1.5 for the ZX81/TS 1000/1500 and the Westridge and Byte Back modems. It has the ability to access the CPM files section of any XMODEM protocol BBS to up or download Timex programs. Features include memory storage of screen displays and an indicator that reports when memory is full. Document- ation and step by step instructions is in- cluded. There are both 16/64k versions. The 64k version stores easily in the Hunter Board for instant recall. Price is $20.


Add these Timex/Sinclair Users Groups to your list. The March/April '85 issue of Time Designs carried a large directory of Groups in the U.S. and Canada. If you are a member of an active group that did not appear on this list, and would like to be mentioned; please send us the information.

Timex/Sinclair Users Group

Hughes Aircraft Company

Att: Liabrary (personal computer club) 8433 Fallbrook Ave.

Canoga Park, CA 91304

contact: Tony Gomez

N.W. Florida 2068 T/S User Group 402 Pine Terrace Circle

Milton, Florida 32570

contact: Edwin S. Salter


TS Connection (3832 Watterson, Cinci- natti, OH 45227) has taken over the Timex computer factory repair service previously offered by Timex in Little Rock, Arkansas. They will repair a TS 1000 for $20 maximun, and a 2068 for $40 max. The 2068 Tech Manual is also carried by TS Connection.

If your computer is on the fritz, write to them at the address mentioned above, or call (513) 27¥-5575;


In a joint venture between John Oliger and Ray Kingsley (of Sinware), a new in- expensive disc drive controller for the 2068 will be available sometime in mid June. The hardware for the disc operating system is being designed by John Oliger, while the software to boot up the controller is being programmed by Ray Kingsley. The main disc interface board is already com- pleted. It will support up to four single or double sided, single, double or quad density 3 to 5% inch drives. The data transfer rate of this board (5;-double density) is 32k bytes per second...the actual rate will be determined by the soft- ware efficiency. Software support is only planned for the 2068, and possibly the Spectrum (in the future).

Further hardware for the controller include a firmware/bank logic/memory board and/or the 64k memory/CPM board. These two boards are furthest away from production, but should be coming along soon. It is hoped that the system will respond like the Sinclair Interface One with Microdrives, and use all the BASIC supported keywords (including SAVE and LOAD). Prices on the boards are still to be determined. It should also be pointed out that the controller is designed for use with the Oliger 2068 Expansion Board.

Specific comments/suggestions con- cerning hardware for the system should be addressed to: The John Oliger Co., 11601 Whidbey Dr., Cumberland, IN 46229. Comments, suggestions, ect. regarding software should be addressed to: Ray Kingsley, C/O Sinware Software, P.O. Box 8032, Santa Fe, NM 87504. If you would like to be put on the system's “inform when ready" list, drop John a post- card.

Mr. Oliger also announced availability of his new 2068 Parallel Printer Port. It is a Centronics type and comes complete with software on cassette. It is also Aerco compatible as far as commercial software is concerned. It is perhaps the lowest priced printer interface of it's kind, with the fully assembled and tested version (with cable) going for $47.90. The kit with parts is $24.95 (add $16.95 for cable), and a bare board is available for $16.95 and includes the cassette. A 15 page user manual is supplied with every version.

et ? te We Te i ee i



E. Arthur Brown has always put out a very professional and slick brochure. The most recent one continues the tradition.

It probably has something to do with Eben Brown's (the owner) experience in the pub- lishing business. The EB7 catalog is on newsprint paper and features a host of hard- ware and software for Timex computers. For your copy, write to: 3404 Pawnee Dr., Alex- andria, MN 56308.

The printer interface cable and soft- ware for the A & J Model 2000 Micro Drive is now available. For information and price write to: A & J Micro Drive, Suite I, 1050 E. Duane Ave., Sunnyvale, CA 94086.

The address for the D. Lipinski Soft- ware Buyers Guide To Sinclair-Timex Products And Services, that we mentioned in the March/ April '85 issue is: 2737 Susquehanna Rd., Roslyn, PA 19001. Price is $20 ppd.

Kirt Olsen, Publisher/Editor of Syntax, told Time Designs that he intends to con- tinue publishing the newsletter. He also mentioned that Syntax (and SQ Magazine) is up for sale. The last newsletter that Kirt put out was the November '84 issue. He told us that the December '84 issue of Syntax should be out in another month or so.

Time Designs Magazine would like to welcome all our Canadian readers "on-board" who have recently subscribed. The number of our friends up north grows each day. It just goes to show you that Canadians know a good computer when they see one. Happy Sinclair computing to you all!


A large number of ZX81/TS 1000 users have “discovered” perhaps the best keyboard add-on that has ever been offered for the price. It is the computer keyboard that was used with the Texas Instruments 994/a. They are being sold at surplus electronic outlets and some Radio Shack stores for the extremely low price of $2.95 to $5.95 (de- pending where you obtain one). The challenge is the installation. We have seen some nice ideas. Hopefully, we will be able to print them in an upcoming issue. If you have a suggestion, send it in and we may print yours.

Te i? ee ee 8



When Bob Dyl of the English Micro Connection contacted Timex of Portugal to see if he could obtain supplys of their new floppy disk system and 2068 “silver avenger" computer (as so nick-named by the British computer press), both of which had been sold in England for several months, he learned of some very suprising news. Antonio Gomez, the Managing Director of Timex Portugal told Bob that they were in the process of bringing the 2068 and the disk system to the United States themselves. In fact samples of each were currently in the hands of the FCC for approval. At this writing a Mr. Olivera who is the assistant to Gomez, is in Waterbury, Conn. at the Timex Corp. headquarters (which Timex Portugal is using for their temporary base) to finish up last minute paperwork, including sign- ing the FCC certification release papers.

This certainly is a strange situation.

A Timex paradox of sorts. Just a little over a year ago the Timex Corp. killed the 2068 in spite of strong support

by both consumers and the computer press. And now, here is their Portugal counter- part bringing back almost the same computer to the American market. It isn't quite known exactly what Timex (U.S.) role in Portugal is and what are the controlling interests. It is known however, that both Portugal and the U.S. owned Sinclair technology rights, and when Timex U.S. dropped out, Portugal continued to use and produce that technology.

Antonio Gomez told Bob Dyl_ that if everything goes as planned, _ they should start shipping units by the end of May. As far as what marketing strategies are going to be used, and who will sell the computers and drives...the de- tails are sketchy. Most of the Sinclair vendors that still exist here, have expressed interest.

The old Timex/Sinclair 2068 that we are familiar with has maintained its silver case and keyboard, but has been retitled simply the "Timex 2068".


It's main circuit board has been a complete redesign, but has maintained the two ROM system, the sound chip, and the joystick ports. It now operates on nine volts instead of fifteen in the original model. In the cartridge port is a plug- in type Spectrum emulator board, and the rear connector has been reconfigured to be the same as that of a Spectrum. So basically, what you have is a Spectrum in 2068 clothes, with some of the subtle advantages of the 2068 remaining intact.

A nice addition to the Timex 2068 is it's accompanying disk drive system called the “Timex FDD." It is a four piece package with a power supply, interface, controller board, and a 3" Hitachi drive. The disk operating system is called (TOS). A CP/M board may be _ released a little later. Portugal is also planning to market the disk system for the U.S. T/S 2068 also, with a suitable interface for that computer.

Retail pricing for the 2068 and FDD has not been set as of yet, and Gomez told Bob Dyl that they were going increase the prices from which they first estimated.

Reaction has been mixed to this major announcement by Timex. Criticism and skepticsm has been voiced by those who still bear the scars from when Timex left the computer market a short while ago. Some disappointment has been expressed as to the incompatibility with existing hardware that has been developed over the past year for the old 2068. But the excite- ment is spreading for the most part, as Sinclair users in general here in the U.S. can expect to see much on it's way as far as support for the 2068/Spectrum is concerned. Quite a bit of software and hardware will no doubt be heading this way from major English companies.

Time Designs Magazine would like to express thanks and appreciation to Bob Dyl of the English Micro Connection, for releasing this information to the American Timex and Sinclair users.



by Bruce C. Taylor Tucson, Arizona

OK all you T/S 2068 buffs, dust off that. 2X81 -or T/S:-1008 (excuse me for a moment ZX81 and T/S 1000 users) and let's do some serious things with your computer. No, I'm not talking about doing your income taxes, balancing your checkbook or writing your first novel, When I say serious, I mean controlling something with your computer. Although you can use your L/S 2068... y0ur -Zk8PF ox 7/8--12000 will do the job very nicely too.

Control what, with your com- puter? Control anything you think Right be: nace to controd. Your lights, your garage door, your coffee pot or even your personal robot. PERSONAL ROBOT? Yes, your lowly T/S 1000 (excuse me again ‘ZX81 and T/S 1000 users) is very capable of nearly anything you want to control with a computer. Remember those personal computer experts who brushed off the Sinclair and Timex computers as mere "toys" good only for learning about the basics of computing, but not for "serious" computing? Those "experts" now say you shouldn't tie up a personal conm-

puter with mundane home control tasks.

Well,-the. experts can be correct half the time.

Even’ in the: face of- current Io bit and soon to come 32 bit home con- puters; don't-tet-anyone sell .the:s bit Z80 CPU computers short. The Z80 based computers are an excellent choice for control applications. If you don't believe me, look to Japan where an assult on the small com- puter market has been launched with their MSX (MICROSOFT EXTENDED) con- puters. One of the prime reasons they selected the Z80A CPU was be- cause of it’s potential for control applications,

In your ZX81 or T/S 1000 con- puters (include the T/S 1500, T/S 2068 and SPECTRUM too) you have the

makings of a very capable computer control system. ALl you. need to get started "interfacing with the world" is to add an input/output (I/0) board to your computer.

But wait a minute, before I launch into the details, you may have the following question. Why build a control project from scratch when I can buy a robot or home con- trol/security system out of a box? First of all, it will probably be cheaper to build it yourself. Also, if you are inclined to tinker and build, you can continually expand and upgrade your system as you de- Sire. This allows you to take ad- vantage of new equipment/component advances, not to mention software upgrades.

Foy ¢€xample, if you: buiit a personal robot as I have done, you may have designed the controlling software to use the input avoidance technique of navigating around the house. With the addition of a range measuring device, like the Polaroid Ultrasonic Ranging Device, you can advance the navigation capabilities to a goal seeking ability... Ties can be done by modifying the software so that the robot seeks open areas to navigate through, much like you seek a doorway as opposed to avoid- ing walls in a roon.

Back to the problem of building an I/O interface for your computer. Several options are available. One was described in a series of articles in RADIO-ELECTRONICS MAGAZINE last year. Another is an inexpensive I/0 board offered by BUDGET ROBOTICS §& COMPUTING of Tucson, Arizona. Both offer eight parallel lines of input and output, and use simple machine code subroutines to give a very fast I/O capability. How fast? The Budget Robotics board includes documentation for a simple optical encoder that can measure inputs up to several hundred pulses a second, and all for only a

few dollars. Is that fast enough and cheap enough to entice you to get on with this computer control area of interest ?

Budget Robotics in fact offers an expanding line of peripherals in- cluding a buffered buss expansion board (currently for Zx81, T/S 1000 and T/S 1500) to allow you to add an almost limitless number of items in your computer control project.

In fact, I have written a book de- scribing these and other projects, to be published by early 1986 by TAB BOOKS... The centerpiece of. the book is "H.EON.R.~Ys" am ent eras ly computer controlled personal robot. He won a Golden Droid Award for Most Entertaining at the First In- ternational Personal Robot Congress & Exposition in Albuquerque, New Mexico last spring. What computer is inside H.E.N.R.Y.7 You guessed it, a Sinclair ZX81. Hardware and software forall control projects is fully explained in the book. A home control interface is also de- scribed.

The expansion board used is the one originally built by COMPUTER CONTINUUM, but has been improved. This board can also De Meged to. build a memory bank switching capability as described in Paul Hunter's series

of articles in T-S HORIZONS Magazine.

Using Paul's non-volitale memory board, control routines can be cre- ated and saved for instant loading into computer memory and easily changed as upgrades to your control project are needed. This method is cheaper and easier than burning Programmable Read Only Memory (PROM) chips, or trying to buy Electrically Eraseable PROM (E2PROM) chips.

Other expansion boards and I/0 circuits can be used which will also do a good job. John Oliger described an expansion board in a Winter 1982 SYNTAX QUARTERLY article. An I/0 circuit using the. 8255 Ppl tere grammable Peripherial Interface) integrated circuit chip is not as fast (no machine code) as the RX-81


I/O circuit, but works fine in many applications. Wiring of the 8255 circuit is included in Budget Robotics expansion board documentation and is described in my book.

To give you an idea of the range of control applications I am proposing, refer to Figure 1 as you ? read the rest of this article, Start- ing with the computer expansion port at the rear of your computer, you will want to add an expansion board if you expect to add more than two peripherials . Next. you wild need at least one input/output (I/0) board. The number? and type of I/0 boards will depend on what and how much you want to control. For example, you could easily add up to four RX-81 1/0 boards: tand. ah 8255. PPI giving you up: to either 56° input: ‘and: 32 output lines or 32 input and 56 out- put lines... Each peripheral, ‘as de- scribed<in- Figure 1,: may require anywhere from one input line (optical encoder) to four input and seven out- put lines (realtime clock).

The following are examples using the RX-81 I/O bord: A realtime clock/ calendar using seven output plus four inputs lines: to read-the=time...A mechanical switch can be read by connecting an input line to ground.

A transistor to transistor logic (TTL) state of low can be read directly by am input line. A logic high state can be read if inverted first, using a 74LS04 IC chip. The Polaroid (TM) Ultrasonic Ranging CiTrecuit-regui res. one out put -lireto initiate a pulse transmit and one input Tine to read the return: pulse; One input line is all that is re- quired-t© read tie status of.a phototransistor in the optical en- coder.

The following are examples > uSingithe: 8255° PPisei reat] Tre outpute lines are-used- to. control a stepper motor driver with one r line dsignating the direction of the motor rotation, and the other producing the step pulse. Ten out- put danes are useédito: control the










Digitalker (TM) Digital Voice Circuit with two ROM (Read Only Memory) word sets with eight lines used to select the word; one to select the ROM word set and one to activate the processor to produce the word.

The following are examples of control easily accomplished using either of the I/O circuits mentioned: Two output lines are required to con- trol a direct current (DC) motor and select either direction where one output line is used for forward and one reverse. Each drives its own transistor switch which in turn activates a double pole, double throw (DPDT) relay coil. The coils are cross wired to the normally closed terminal of the opposite relay so that power to the motor cannot accidentally be applied in















both polarities at the same time, causing a direct short circuit. For appliance or home wireless control Switching, one output line is re- quired for each on/off switch. Here each output line controls a transistor switch which in turn controls a relay. A light emitting diode (LED) can be activated in conjunction with any output line activity.

These examples are provided as food for thought. You can control virtually anything with your computer. Just use discretion. I would not recommend trying to control Aunt Mary's respirator. One last point, all the examples in Figure 1, plus more, can be controlled together by a single computer (ZX81, T/S 1000, ect.). Happy controlling.



FOR THE T/S 2068

by John McMichael The following is a compact machine Bozeman, Montana code routine that provides a 2068 user with digital joystick position information and button status at machine code _ speeds. It was originally designed to be of use in upgrading game programs from key- board control to joystick control.

Basically, the two joysticks are FIG. 2 - JOYSTICK DATA LOCATIONS controlled via Register 14 of the Pro- ADDRESS DATA grammable Sound Generator Chip. Addresses il ge a as sat st 4h are transfered by port #245 and data 26715 STICK RIGHT by port #246. To read a joystick, 14 ; 26716 STICK LEFT is written to port #245, the B_ register is loaded with stick no., and the data 26717 STICK DOWN is read from port #246 as a_ single 26718 STICK UP byte with direction/button status bits ecto as shown in fig. l. 26719 "FIRE" BUTTON

FIG. 1 - JOYSTICK DATA BYTE Bit - 6 5 4 3 2 1 @ | not used | \ i. =e button stick stick stick stick depressed right left down up The program in fig. 3 is a _ machine

The routine, as presented in this code loader which puts the machine code article, resides ina 1 REM statement, into the 1 REM statement. although it can easily be relocated. As the resulting 1 REM machine

Providing the second display file code lint is partially unlistable, any is not used, the first available address Subsequent program lines will be unlistable , in acd. "REM “statement 92> 26715. This unless...the[>]cursor is set to a line and the next four addresses are where no. equal to.or larger than the next the results of reading a joystick will line no. after the 1 REM and the following » be stored (see fig. 2). After the routine two direct commands are entered: POKE is. called, a >1 421. bei sfoumd° “in’ the 23660, (your next program line above addresses corresponding to positive switch the 1 REM line): POKE 23661,0. This closures and O's in those addresses cor- will cause the automatic listing to start responding to negative or "open" switch at your first program line. conditions. Enter and RUN the following machine

code loader:

ee AO ee ee eee

Fig. 5 is the OP CODE listing for the 1 REM routine.



Lines 10-40 of the loader can be DELETED and the remaining 1 REM machine code line can be SAVED to be later MERGED with any program that is’ being up-graded to joystick control.

At the point in a program where joystick information is needed, address #26736 is POKED with the desired joystick's no. (1-LEFT; 2-RIGHT) and the routine is called at 26720.

By PEEKING addresses 26715-26719, the sticks' position and button status are obtained.

The following program is a_ typical example of how the routine may be used to move a single character around the screen with a joystick. The program will stop when the "fire" button is’ pressed.

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by Dick F.


Canby, Oregon

One of my pet beefs with many computer programmers is their lack of con- cern for identifying the basis for their

programs. The display of the formulas/ equations used, would help the user decide if the program is indeed the one needed for his -{or her) calculations. It is often not easy to pick this information out of the program because of the way the programmer had to chop up the formula/ equation. Also there should not be the need to spend a lot of time trying to identify the information needed.

The following program is substantiated as to formulas. This makes it easy to sub- stitue as you wish. However the problem is complex in that several sytems are involved in developing a problem display. The formal graph with x and y axis, notations and scales provide an example for similar displays. The derivations for generating an equilateral triangle as well as drawing an inner and outer circle touching the tri- angle shows the steps. The chart coordinates have suitable divisions marked off, as well as enhancing every 5th division. The end product, instead of just displaying a tri- angle and 2 circles, shows the result of calculating a problem with interpretive results.

The first step is to draw the x and y axis, scales, divisions and headings. The radius of the outer circle is to be 40 inches. Use a scale of one pixel as one inch. Therefore, we need to provide for a figure 80 by 80. For a nice balance, place the circle center at 95 (x axis) and 80 (y axis). To allow space for x and y axis data place the x axis 20 and the, y axis at 25. Position markers every 10'pixels . (inches) and enhance every 5th mark. Remember that all positions are with respect to 0,0 for PLOT (bottom left corner) and 0,0 for PRINT (top left corner).

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Lines 10-190 generate the axis, markers, axis numbers and axis names. Many lines include a printer correction

factor of 1.24 (Timex 2040 Printer). This is necessary to produce a symetrical image. After all, who wants to excuse his (or her) equipment for making egg- shaped circles and non-equilateral tri- angles?

. To review the derivation of the correction factor, just DRAW a _ square of good size, and make a printer copy. Measure the height and width (use a dec-— imal or metric scale). The ratio of these dimensions is the correction factor. Now re-draw the square, using this mul- tiplyer. For example, assume the square was drawn with PLOT 30,30:DRAW 80,0: DRAW 0,80: DRAW -80,0: DRAW O,-80. For the 2040 Printer, you would change the lst and 3rd DRAW to 1.24*80,0 and -80* 1.24,0. Check your printer to see if it is the same.

Lines 45-110 put in the markers on the x axis, and lines 120-190 put in the y axis markers. RUN the _ program from 10-190 and confirm proper display. CLS and the "graph paper" is now ready to plot the 3 figures. It is now time to calculate the dimensions for the figures and decide where to place them. Remember that we are going to have a display with measuring capability of the finished


1 9 figures.


Calculations start with determining the sides of the equilateral triangle from one dimension, the radius of the outer circle. That has been given as 40 inches (3rd paragraph). Key in lines 395- 470. DELETE later if desired. This part will draw a right triangle (any scale) and from the hypotenuse (the radius of the outer circle), we can determine % the base and the radius of the inner circle.

These formulas will be used: