TRS-80 Computers: TRS-80 Model I

Introduction / History

Before The Birth

Remember the CB craze? From nothing in 1970 to over 20% of the corporate business in the early 70’s, CB radios not only contributed to Tandy’s profits, but brought an entire new group of customers into Radio Shack stores. Indeed, things were so good in electronics that Tandy Corp. sold off all its other subsidiaries including the original, Tandy Leather, in 1975. But the abrupt collapse of the CB craze in 1977 left the company in disarray.

Enter Don French and John Roach. French started at RS at 16 as a salesman in the Sandieogo in 1966. Youngest saleman ever, youngest store manager ever (he got a store at 18 years old), and moved to the corporate office at 23. In 1974 pupularte electronics did a article and on a 8008 processor as the first 8 bit microprocessor. Designed by Jonathan Titus(?). He read the article an dbought the boards and built it up. 128 bytes of RAM. It had a nice case, a lot of LED’s. He was so intrigued with it because he takled to Jonathan and asked how many boards were sold. Around 8000. That hit Don. Don thought this was interesting because when he was promoted to Corporate office 1973 one his first new product lines was project boards. It was a printer circuit board designed for various small electronics, with all the parts being able to be purchased from RS. It was a big win because it cause orders of manginutude demand for certain items. He could do whatever he wanted to do with the project board line – it was new, and wasn’t changing anything. He was talking with his semi conductor customers in 74, and in 75 Don bought an Altair. Don bought up a complete system. Took the full board and took it into the factory and put all S100 connectors and had it wave soldered. A lot of memory and bought a pertec icon floppy drive for it, a lear signler AM3 (blue modern looking), and had a decwriter. Started with a ASR33 which is how he got MS BASIC on it. He wrote some sofyware for him to help him manage the product line at rs. RS sold around 2400 stock keeping units, and there were 7 buyers. Buyers were product managers and were responsible for one of a kind gross margin every quearter. So to do that, you had to put the stock number, the wholeasle cost, and the retail price on a colmnar pad and add them up, and calculate the gross marcing. Well, 2400 items divided by 7 is 350, but Don had 1,200 of the 2,400 and the other 1,200 were split between the other 6 buys, and that’s ebcause he had every resistor, ever capacityr, every transistor, every CPUI and that was a pain, so he had a computer at home and wrote a program that would do his one of a kind automated. He taught his then wife, Beverly, how to use the system. He printed out the OOAC and gave it to the re-buy manager and she said what’s this. He said its my ooak. She handed a columnar pad and said ‘do it right’.’So he wrote it up, using the worst writing you have ever seen. Around this time, 1975, he had written John Shirley (president of Microsoft) who was in Europe as VP of marketing merchandising (same level as Don’s boss), and Don wrote a telex to John saying that he was wowking on computers, and that it would be the next big project. Don kept thinking about , but to get that level, he needed buy in from the whole company. He wrote back saying don’t waste my time, we can’t sell computers. He was absolutely coorect it turns out. RS could not sell a computer. People would buy them, but RS couldn’t sell them. RS knew nothing about it, only Don and Steve, and Don had hired a frmer store manager in California and one other person to open the first computer center, after it was introduced. RS didn’t plan on selling any. So, what happened, around 1976 early fall, they were required to work 5-1/2 day weeks. Because RS stores were open 6 or 7 days, so they needed to be there sat morningsd for the stores if needed. Don had hidden a computer behind his door that he written software for, but didn’t want people to see it. Word got around that he had it, and Charles Tandy was on his way in and was on the warpath. He got there, and called a meeting saying why can’t RS be innovative. Advent (speaker company) had come up with a brand new high tec speaker, and RS had nothing to compete with it. In the meeting they were talking and people were tossing out ideas and Don’s stuff was nothing to him. Even though it was a good percentage of the business, it took 1200 items to do it. Citizen band was 40% of the business in 1976 and that was just a few items. Don didn’t say anything during the meeting. Product managers were called buyers because they did the initial buy. One buyer said that Don has a computer in his office. Charles responded something alon the lines of “so what”. Now don had been taling about doing a computer to Roach and others, and since he had to go to Silicon Valley often. He was the product manager for parts nad pieces. RS always bought surplus, that didn’t meet mill spec, but were good enough for hobbyists. So don would go out there and buy the chips and products. he had to look for new things. As the west coast computer fair started, Don would schecule his buying trip at the same time. John Roach was out there as the same time as the faire in around 1975-1976(?) and Don invited him to go to the show. Roach knew that Don was working on it. Do Roach came along. And they got there and Don thought I just ruined any chance bec ause there is lines around the block. They waited on line anyway, and when John got back to forth worth he wrote a memo to charles wsaying there must be something about this computer. He went out for another buying trip (calculator and watch chips), as national semiconductor was the largest vendor for those and Don’s line. So he was out there doing that by himself and someone else (Don in Forth Worth) and Don had been working on the pace and scamp processor (National semiconductor). And Don was building a project using them. It was his product line. But the issue was to get an expensive chip into the product line. They were 100 and 150 each. That was too much. John was out there with national talking about calculator chips and one of the prsentors were leninger. After a meeting, John asked Steve what he knew about microprocessors in computers. Don was told by Roach and Steve that they talked about the scamp and to get more information they should go to a byte shop. So Roach planned to go tone that evening. Roach got to the byte shop and there was steve. And now they are getting more intruiged. Don has no idea what happened during this session. Roach gave steve’s information to Don to have steve come in and interview; as they had no idea how to interview someone like steve. So Don called in Steve and they hit it off. Susan and Beverly hit it off (wives), so they hired. Steve moved to forth worth and was given an office in the semi-engineering area (customer support) to do higher tech things. Steve was working on a PC board. Steve knew the only way to get a computer into RS was to get it through Don’s product line. Things changed on saturday when a heavy box came in from a customer and inside was a project board digital clock, and the instructions said soldder everythig to the bottom of the board. The owner did that! Everything was soldered. A pack of solder across the bottom, which blew the board. That changed the whole idea about a project. Steve was s involved in the desktop as was Don. It was steve’s physical design with Don’s concepts. They started working on it. Don was next door in his office and was over there working with steve, and normally nevre lies. He got a call from Bernie Appel’s secretary (don’s boss) asing where he was, and said “if you are working on that god damned computer, your fired”. Don lied and listed the other things he was working on over there. Bernie did not want a computer. But Roach was interested because Steve knew more about watches and calculators than anyone else, which is why Steve was brought in. Don and Steve built up in late 76 they built up a mock up of a working computer and had made the decision goinv with the Z80 and not the scamp, partially because the s100 was basically z80 based, and that don had a complete 8080 development system – he had his altair, his percom cp/m OS, and all the development tools. RS used those tools. They spent no mo0ney on development or software. They used Don’s personal stuff for free since Don wanted this so bad. They took a RCA monitor that they had, the keyboard was in a mock-up case, and underneath the table was the wire wrapped rack that had aeverthing. Don had written “H and R Shack”, a simple 1040 program – 4k in their basic, a modified tiny basic, integer aritmentic.Maximum was 32K. Charles comes in, still smelling of the cigar, and he sat down at the computer and they told him what to do. He put in 100k salary to start, and it dumped. Don said take a pay cut, maximum of 32,000 and we know we have to fixe it. So charles chose a lower number and it worked. They all sat aroudn the conference table and asked how many he could sell. Don and steve hadn’t discussed it, but somehow both said 50,000. They laughed After discussion they decided to make 1,000. Remember, the concept behind it, which was never stated, was that RS was not innovative. This was innovative. That’s the reason why he got the buying end to do it. To show that RS was innovative. They had no interest in the computer business. Only to show innovation. Charels kornfeld roach bernie and all the other people at the meeting decided to make 1,000. So they were yay, we were going to have a computer ad din’t care how many because h just wante da c omputer in the line. So they created the 26-0000 series and it was Don’s. They start working on it. Steve decided for a better basic. Don got a hold of bill gates and negotiated with him. Don was told to negotiate for … some time before that Roach came to himn to say 3,500. Since we have 3,400 stores, we talked to the data processing group, and felt that the stores could use them for inventory WHEN it fails. So at 3,500 they knew they neded a better basic. They were discussing what the price would be, and he was talking per-ubnit, but Donw asn’t going to buy per unit, so they based the negotiation on a 3,500 unit buy. Gates felt this was not enough for him,a nd wanted to base it on 10,000 systems. So a flat fee was paid was paid for basic, regartdles sof numthe bymbuyer of unites. They wrote the basic, which was to be level 2 basic. They needed manuals, and so Don called everyone he could, and ultimately called his collegel professor Dave Lien,a nd asked if he would do it. Dave jumped at it, and subsequently crteated a computer book publishing company. The product line was cvoming together. They put an expansion port on it similar to a S-100, but not a S-100 bus. Don feels this was the death knell, as the open nature of the box due to the bus, limited the ability stop the RFI. So they had a complete computer, RCA TV, li-chen wang basic (tiny basic), and was designed with only 4K because the design goal was to make a $99 computer (w/o monitor) as that was what was approved; so they missed it by half. That’s why it had only upper case (saved 97 cents), li chen(because it was free). But after the level 2 basic was secured, they knew they had to 16K because it wouldn’t work with 4K> Bill put in everythin gto make the basic work for the ters-80. That basic became his basic for all others, including IBM. Getting the RS contract and the numbers that were sold over the frist 4 years, where RS owned the market, really made microsoft because that BASIC became the standard – everyone wanted the same basic with the same commands. If they could have the same basic, then otyher hardware vendors would want to buy it. That’s why the S-100 and TRS-80 through IBM were a modified (or demodified r/s basic, with the proprietary r/s stuff removed). Announced 8/3/1977 but without much press coverage at the Warwick hotel on the same day as a bomb threat, as 100,000 people left their offices and shut down during the press conference. The computer was well acceptyed. The next weekend was the boston computer show. Don took the total production run to Boston (3 computers). He was swamped. Booth was swamped. 5-10 people deep. All 3 networks were there to talk about it. Don got back to Forth Worth on Monday and was supposed to then go to Japan the next day on a routine buying job. But the phones wouldn’t work. This was the day of trunk lines, and every phone had copper. And the tunk was all used from the calls. They moved Don from his office and ptu him in the coonference room and they hired him an admin to deal with the calls. Because RS did not have the computer made, and didn’t know how many they would need, they didn’t make all 3,500. There was no production so they could back out of it. Don had to take calls, and the commodore pet had just come out. Commodore was a desk manufacturer. And the concept was Don’s concept. Chuck Pedle was at commodore. Chick was a vendor of Don and RS didn’t want it. Don was aft4raid to talk to anyone at RS about it. But Don would talk to Chuck and describe it. How do we know? They keyboard in it was what was Don was recommending to use. A microwave type keyboard. It was DOn’s concept. And apple had just released the apple ii with the case in July. Apple was bankrupt, they had no money and were trying to create the industry. if it hadn’t been to RS doing it when it did, the computer industry wouldn’t have started then. Because it took a compan y the size of rs to do it. The S100 computers were not selling many. Apple only sold 7900 computers in the time frame that RS sold 100,000 (1 year from announce dates). It took RS or a company like RS (but there wasn’t any). Allied Electronics had been bought by RS. Lafayette Radio was still working and tried to hire Don to do it for them, but they weren’t big enough (1/10 size of RS). RS had 3,400 stores. So don, as a customer support, he gave the customers a choice and said RS won’t have them for at least 90 days and are being prioritized by orders. You can wait for them to come out. People would always say ‘how many in front of me’. DOn said OR you can buy the apple for 2,100 or go buy the pet for 899. Or wait for RS at 599. Leslie and his admin, did this day in day out, and Japan was cancelled and he never returned. Based on these orders RS decided to open tandy computers they took away all his other product lines, and was computers only. He was 100% computers on that monday. Charles started talking about. Tandy center was a big tower and had retail space. Charles decided he would open a tandy computers there. Putpose of tandy computers was market research. Don had all the S-100 product lines as well, and worked with another executive to open it. Only Don and Steve knew antying about computers. Don pushed for CP/M as the DOS, but in the design CP/M was out of the question because they took the low interrupts to keep the cost down, and CPM needed those. Normal CPM would not work. So they looked around and found Randy Cook to write TRSDOS. He wrote it based on Don and Steve’s concepts using what they knew about CPM what was needed in a DOS. Don had left before TRSDOS came out. Charles Tandy died in November 1978, and Don left right after that. He doesn’t know anything after that. Steve ran the R&D department, but RS panicked when the PC came out, and instead of following IBM. IBM wanted to own the market and RS did. So RS didn’t follow IBM’s lead and did not make it compatible, and that was the death knell for RS. Don had left shortly after Charles passed away. One satierday Don went to Charles’ office on the top floow without permission. Said ‘you know, i saved RS.’ he didn’t agree and said ‘you’re full of shit.’ Dn said ‘think of it, CB was 40% at the beginning and now its almost 0. In 1977 computers was 0% of our business and its now 40%. So RS business did not take a big hit when CB died, as computers offset the major sales decreasse and I want something for this.’ They talked. Don wanted a VP title over computers and wanted a large bonus (no numbers). Charles agreed as DOn knew the market and the technical. When he died, Don knew he was screwed because he went to Kornfeld and Kornfeld said no. Not one to get mad right away, Don thought about his response, and said we’ll talk about it later. Don cleaned out his office on the sly and got ready to leave. Don talked to bill gates about what he would do. Gates was willing to hire, and called Don ruthless. “Youre so ruthless”. I wasn’t ruthless, we had a win-win deal. I raised the quantity to 10,000 because I thoguht it was a fair deal for the both of us. No one knew how many we weould sell, and the only rule I had was no royalty. I raised it your number to get you to do the modifications. Ultimately Don decided not to join, and to start his opwn business making software for the TRS-80, as FMG. * – How can I get emails to you to avoid spam? * – When did L1 to L2? * – E/I? In late 77 and they knew it would be huge and after the level 2 was announced, but not available until march 78. Once they had MS basic, they knew they had to expand the computer more and got with seagate floppy disks. Don was doing the best he could do without making a lot of commitments in case they were right. The E/I was done right after the level ii. They knew they had to get the memory up and you knew a disk controller. Cbarles tandy’s nephew took over for Don. Go back to numbers: This was a publicity stunt. They were not ready for the hit. Ateve had been moved to the stockyards to get away from the office. Steve weas working to get floating point working. He was stressing about it. Trying for several days to solv the problem. Hwe qwas talking to Don one day and it was still a bug. He called and said “i got it solved” Don said what did you do He said, I did a core dump. Don said there is no core. Steve meant he weant to the bathroom. Roach had joined Tandy in 1967 as a data processing manager and, by 1976 had been promoted to vice president of manufacturing. Don French was on the West Coast in the heart of Silicon Valley and had been trying to get Radio Shack involved in computers, even though his boss, Bernie Appel (recently promoted to president) was opposed. In mid-76, Roach and French were traveling together on the West Coast and stopped in to see National Semiconductor’s new SC/MP microprocessor. While there, they met Steve Leininger who briefed them on the hardware and software. Roach and French were impressed with Leininger and wanted to hire him to do some consulting. However, the National Semi marketing people refused to part with Leininger’s address or phone. Next stop on the itinerary of Roach and French was Paul Terrell’s Byte Shop on El Camino Real. What a surprise when they found Leininger moonlighting there as the night sales clerk. They asked him about consulting, but four weeks later asked him to come down to Ft. Worth to see the facilities.

At the end of the day, Roach offered him a job on the spot. Leininger accepted but found that Tandy wasn’t really committed to a computer just yet. For six months he, in his words, “played around with a couple of things-an audio pre-amp, a computer kit, and some other minor projects.” But as CB turned more and more sour, there was a growing cry at Tandy for something new. They finally moved Leininger off into a room of his own with instructions to build a computer. Leininger remembers it well, “It was there that I wire-wrapped the predecessor of the Model 1. I even put Tiny Basic with the graphics extensions in a 2K ROM.” (Tiny Basic was written by Dr. Wang at Stanford and placed in the public domain. Leininger had helped implement it for People’s Computer Company.

The Birth

The first ‘Tandy’ computer was the Radio Shack (TRS – Tandy Radio Shack) TRS-80. Called just the TRS-80, it later became known as the “Model I” when the TRS-80 Model II was announced in the summer of 1979.

The Model I was invented by Don French (A buyer for Tandy) & Steve Leininger (The head of the Homebrew Computer Association) and first announced on Wednesday, August 3, 1977, in Radio Shack Press Release 7741-A, at a press conference at the Warwick Hotel in New York City.

Radio Shack said they anticipated deliveries to start in two weeks, but was quite unsure of the product, thinking that they might sell 600 to 1000 the first year. It was also the most expensive single item Radio Shack had ever carried to that date. They required a $100 deposit to place the computer on order. In actuality 10,000 units were sold in the first month! Radio Shack was swamped with orders, and delivery times quickly fell to months after order. By early November of 1977, Radio Shack was delivering 16K RAM units with 5 digit serial numbers that had been ordered in early September. At that time, there were separate serial number sequences for 4K and 16K machines.

The Model I began with a $599 Level I System with 4K RAM, monitor, and cassette, with all cables and adapters ready to go (except that it took 3 plugs, so you probably needed to purchase a power strip). The Level 1 was soon replaced by a 16K Level II System. The Level II (first model) was updated to include a numeric keypad.

The Evolution

Soon after Level II showed up the Expansion Interface was made available for $299. The Expansion Interface had room for an additional 2 banks of 16K RAM and an RS-232 card. In addition the Expansion Interface already contained a floppy disk controller and a control circuit to allow two cassettes to be hooked up at one time and controlled by the computer. The Expansion Interfeace was a change from the original announcement, which declared that there would be an expansion box with a 5 slot S-100 chassis for the unit. (No price was ever given for the S-100 box that I recall.) Mike Yetso has advised that there was also an 8K RAM for an additional $99, but only a few of those were ever made, and Mike does t believe ANY customers EVER got an 8K upgrade kit – with all 8K computers being upgraded to 16K.

Disk drives showed up the following year for $500. These were Shugart SA400 drives with about 80K of storage. The Centronics Line printer showed up as well.

The Death

The Model I was discontinued in January of 1981 due to its failure to meet the FCC’s Radio Frequency Interference rules. By the time it was discontinued, the Model I had sold over 250,000 units (which was 197,000 more units than Tandy’s CEO had intended to manufacture). A Model I (with Expansion Interface and Floppy Drives) is currently housed in the American History Museum at the Smithsonian Institute.

The Clones

There were a number of Model I clones, including:

• Dick Smith System-80 (in Australia)
• LNW-80 (in the United States)
• PMC-80 (in the United States)
• TRZ-80 (in South Africa)
• Video Genie (in Europe)

Radio Shack’s Description of the Model I

What is a Computer

Not too many years ago. the pocket calculator we take for granted today could have passed for a powerful computer, and one worth a great deal of money Today, however, there is much more to the definition of a computer.

The computer is in some respects like a super-power calculator, yet it is very different. Calculators work with numbers. They add. subtract, multiply and divide. Computers work not only with numbers, but with alphanumeric data -names, words, stock numbers. A computer can be programmed to repeat the same function over and over. It can compare a list of stock numbers with one you have asked it to find or alphabetize a list of names. It can logically evaluate information given to it, and act on its findings. It can store large volumes of data for future use or reference. It can converse with its operator, asking questions like “Your totals don’t balance. would you like to put the data in again?” or “Would you like the results printed out, or displayed on the video screen?’.

Obviously, a computer is much more than just a “number-cruncher.” It is literally an extension of the mind. It is to man’s mind what the lever is to his arm – a machine capable of increasing his effectiveness. It can free you from repetitive exercises which do not require human judgement. It can provide facts and figures with extreme speed, giving you the time to exercise your judgement thoughtfully.

Not many years ago, a computer with the power of the TRS-80 would have cost over a million dollars. The equipment would have filled large rooms. The advancing technology of integrated circuits led to the microprocessor – literally a “computer on a chip.” This, in turn, drastically reduced the size and cost. The TRS-80, a product of these advances. is manufactured and sold only by Radio Shack.

Perhaps the best way to really explain the computer is to ask the question …

What does a computer do?

Large computers are well known in the business world for their ability to do bookkeeping, billing, payroll, inventory control. and analysis and forecasting of business data. Laboratories, engineering firms and universities have used computers to analyze volumes of data and numbers in a wide variety of applications.

As we said, a computer works with alphanumeric information, not just numbers. It can alphabetically sort a mailing list, find subscribers who have not renewed, locate slow-moving inventory items, write purchase orders based on sales trends and current inventory levels, or simply catalog your butterfly collection. And it can become an automated teacher of math, spelling. American history or what have you. For entertainment you can spend hours playing really challenging computer games, from chess to space war.

The TRS-80 Microcomputer System is capable of performing all of these activities. In general. it differs from its larger cousins in speed and the amount of information which can be kept on line at any one time. Keep in mind the TRS-80 isn’t a panacea -it’s a computer. Study your needs carefully and buy the TRS-80 system that’s right for you – expansion could be the answer. For example, a simple Level-! 4K inventory system could handle 22 items (64 characters per item), while a disk system TRS-80 could store about 1300 items per data diskette. Remember, too, that you’ll need to write programs (our manual tells you how) or have them prepared to suit your specific needs. Visit a nearby Radio Shack for help in choosing your system.

Why a personal microcomputer? Because today’s complex lifestyles require a method of getting more things done in less time. The TRS-80 has made true computing a reality for the small business, laboratory, classroom and the home. Radio Shack’s TRS-80 is the personal computer for anyone and everyone!

The TRS-80 System

Radio Shack’s TRS-80 Microcomputer System is fully wired, tested and U.L. listed for electrical safety – you can put it to work immediately! It’s ideal for finances, education, accounting, lab use – even for home entertainment. And it’s the computer with a full line of accessories being delivered now with more to come in the future.

Basic TRS-80 systems include a 12″ video monitor, CTR-41 Realistic battery/AC cassette recorder, power supply, 232-page user’s manual and a 2-game cassette tape for playing Blackjack and Backgammon.

The TRS-80 comes to you ready to be programmed, either from pre-recorded cassette tape or from the keyboard. A “program” is simply a set of step-by-step instructions telling your TRS-80 what you want it to do. The TRS-80’s programs are written in easy-to-learn, plain-English BASIC programming language (BASIC stands for “Beginner’s All-Purpose Symbolic Instruction Code”). The user’s manual includes a beginner’s course in BASIC that’ll have you “talking” to your computer in no time. The TRS-80 talks back to you via its 12-inch video screen.

Inside the 53-key professional keyboard housing is the actual “brain” of the computer – a powerful Z-80 microprocessor that serves as the central processing unit (CPU). Programs and data are stored in internal “memory chips.” Our lowest-priced TRS-80 computer contains 4096 bytes (4K) of user memory, or RAM (a byte being roughly equivalent tp one typewritten character and made up of eight electrical signals called “bits”). It can be expanded to 16K within the keyboard unit and to 48K by using the Expansion Interface with additional memory options.

Note – the Z-80 is an 8-bit microprocessor and can address a total of 64K of memory. Both ROM and RAM are addressed in the TRS-80, along with some internal “overhead.” In a 48K RAM configuration, the last memory address is 65,535 -the usual ending address for a 64K computer.

The “Read-Only Memory” chips contain the “BASIC interpreter” software. The interpreter accepts plain-English commands and statements from the programmer and translates them into the numeric language ofthe Z-80. You can access the 2-80’s numeric “machine language” directly by using our “T-Bug” monitor program, available on cassette tape, or in “assembly language” by using our “Editor/Assembler” tape. (Both of these tapes are suggested only for advanced programmers with a knowledge of machine and assembly language.)

The Realistic cassette recorder lets you record and play your own programs or use one of Radio Shack’s prepared programs – simply run the cassette and begin computing. The recorder is included free of extra charge with each basic TRS-80 system. Other recorders may be used – with varying degrees of success – but only if they have automatic recording level capability

The video monitor looks like a standard television set without the channel selector. It features a wider bandwidth than most TV sets for a shatper display of printing and graphics. The monitor operates on ordinary 120-volt AC. 60 Hz house current. Foreign versions are available in other countries and are sold only overseas by Tandy Electronics outlets. The computer cannot be connected directly to a standard TV set.

For access to other hardware, the TRS-80 utilizes a unique 40-pin bus (connector system) that can attach the TRS-80 to our Expansion Interface, or other external devices. Housed in the finest ABS material, the TRS-80 is virtually unbreakable. It may be left “on” for extended periods of time with no adverse effects, as long as the cooling vents are not obstructed.

Who can use the TRS-80?

Thousands of people from all walks of life already own the TRS-80 Microcomputer. Why? Because they saw that it could serve to enrich their lives. At work and at home. the TRS-80 is exceptionally versatile. And that’s why so many people are using it.

Businessmen find the TRS-80 gives them the edge on the competition. So much of their time is spent on tedious, repetitious paperwork that they often find little time to devote to the more productive areas of their job. But with a TRS-80, tasks like inventory, general ledger posting, payroll and accounts receivable can be processed quickly and effectively. Accountants find it invaluable in tax preparation, cost accounting and in keeping clients’ records.

Engineering firms, manufacturers and large businesses use the TRS-80 for specific jobs too small or too costly to run on a large computer.

Programmed to catalog specimens, classify drugs and perform needed statistical and data manipulation, the TRS-80 microcomputer becomes an inexpensive and reliable clinical lab assistant.

The TRS-80 is an invaluable – yet affordable – educational tool. Computer-assisted instruction is ideal for students who require repetitive instruction and immediate evaluation of their progress.

And homeowners find more uses for the TRS-80 every day. Already they use it to manage the household budget and to keep purchase dates, serial numbers and repair history of home appliances and valuables.

How do owners like our TRS-80? A school system tells us that the TRS-80 has made computer-assisted instruction available to them for a fraction of their previous cost per student-hour. A Civil Engineer reports laborious structual concrete beam calculations requiring hours are now completed in less than ten minutes. A father writes to tell us “this investment is one of the most significant in value to our family and to the future education of our child that we have ever seen.”

The limits of what the TRS-80 can do depend upon the creativity of the user, and his or her needs and imagination. As an educator put it, the TRS-80 “makes possible the tapping of human innovation and creativity on an unprecedented scale.”

Why the TRS-80

Low Cost. Seldom has such a technologically advanced piece of electronic equipment been made affordable to the general public. But Radio Shack broke the price barrier, and made the personal computer a reality.

Value. Most people regard their TRS-80 as an investment, and often it yields a return that exceeds their fondest dreams. That’s because TRS-80 is what a personal computer should bea powerful system that’s easily expandable.

Availability. The TRS-80 and its accessories are supplied through Radio Shack outlets nationwide and we have over 5800 locations. You can stop in at one near you and actually see and try the TRS-80 before deciding on your purchase.

It’s easy to Use. Our Level-I TRS-80 system allows the user to learn programming with absolutely no previous knowledge of computers or programming. Our superb user’s manual is written in a light and humorous style that makes learning fun. And the TRS-80’s BASIC language is stored in permanent Read-Only-Memory (ROM), so it’s ready to use the second you turn on the power.

It’s expandable. Even the smallest TRS-80 system can be expanded into our largest business system – and you pay no “premium” for not having purchased the biggest system in the beginning. With the Expansion Interface you can add more memory for a system with up to 48K RAM, plus printers, disk drives and much more. And you can convert to one of the most powerful microcomputer languages available. our Level-II BASIC.

We build it ourselves. To insure highest quality at an afiordable price, Radio Shack designed the TRS-80, and we build it in our own factories. We have taken maximum advantage of state-ofthe- art engineering and our manufacturing expertise to produce the best value-to-cost ratio on the market.

Service. If repairs are ever needed, Radio Shack has a nationwide network of over 50 service centers to minimize “down time.” You simply return the component in need of service to your nearest Radio Shack store – we do the rest.

Reputation. Radio Shack, with 58 years’ experience to our name, is the nation’s leading electronics retailer. We’re backed by our NYSE-Listed parent, Tandy Corporation. You can depend on us in the years to come to stand behind our product and to offer an ever-growing line of both accessories and programs.

The Offerings

On display at over 7000 Radio Shack Locations, TRS-80 Model I is a microcomputer you can see and try before you buy. It’s a proven system, used by business people, professionals, and “just plain folks” everywhere for accounting, education, lab work, budget management, word processing – even games at home. Model I comes wired, tested, and ready to operate. It is supported by our growing line of software (programs for specific jobs) and accessories which are available either “off-the-shelf” or on a quick-delivery basis wherever you see the Radio Shack sign.

4K, Level I “Starter” System (26-1051): Our lowest-priced Model I TRS-80 computer contains 4K bytes (4096 characters) of RAM (Random Access Memory). RAM is internal memory space accessible to the user for program and data storage. This system is programmed in “Level I BASIC”, an easy-to-learn computer language that’s ideal for beginners. To get an idea of the system’s capabilities “right out of the box,” see the Level I software listed on page 9. The 4K, Level I system is modular and can be upgraded at any time to meet future requirements. Includes computer/keyboard unit, 12″ video monitor, cassette recorder, game cassette, and a superbly written user’s manual that teaches you to write your own programs. U.L. Listed.

16K, Level II System (26-1056): Level II is an advanced version of BASIC that offers vastly increased computing power and advanced programming features for greater versatility. The 16K, Level II system is the “standard” Model I ooniguration and ideally suited to many small business and professional jobs. It can be equipped with a printer and other accessories shown on the facing page. Includes all Level I hardware and Level II Reference Manual. Computer/Keyboard unit includes built-in 12-key numeric datapad. U.L. Listed.

Level I

Radio Shack’s Level I BASIC really packs a lot into 4K of ROM to produce a thorough but easy to understand computer language. It’s the ideal entry level programming language for the computer novice. In fact, BASIC is an acronym for “Beginner’s All-purpose Symbolic Instruction Code.” Level-I includes most standard BASIC commands, video graphics, cassette input/output, floating point arithmetic, numeric array, and limited string variables. If .you can read and write English, you can probably learn to program with Level-I BASIC!

The Radio Shack TRS-80 Level I language is the way to learn computer programming. It’s a simplied version of the BASIC (Beginner’s All-Purpose Symbolic Instruction Code) programming language, and allows you to “talk” to the computer using simple English commands and statements. Even if you have no prior knowledge of computer operation or the writing of programs, our easy-to-understand teaching manual lets you quickly learn how to program the TRS-80. Level I includes most standard BASIC commands and also several outstanding features, such as a screen display of 16 lines of 64 characters. 48×128 video graphics, 250-baud cassette input/output rate, floating point arithmetic, 6-digit numeric accuracy, single dimension array, limited string variables, command abbreviations, and error codes. Level I is stored in 4K of Read-Only Memory so it’s ready to use the instant you turn on your TRS-80 Computer.

Level II

If you’re experienced with Level I, be prepared for some pleasnat surpises with Level II. Level II is a far more advanced or “extended” version of of BASIC, and offers vastly increased computing power (its execution time is 30% faster than Level I’s) and additional features. You can choose a screen format of 16 lines of either 32 or 64 characters – both with automatic scrolling, and the 500-baud cassette input/output rate is twice as fast as Level I. In addition, Level II offers multi-dimension arrays, comprehensive string variable handling, automatic line numbering, tracing, PEEK and POKE, call-up of machine language routines, printer commands, and 23 specific error messages.

Versatile program editing with extensive editing commands allows easy modification of your programs. Level II offers increased numeric accuracy of up to 16 significant digits; intrinsic functions remain at 6-digit accuracy. Program lines, logical lines, and string variables may be up to 255 characters long (overflow moves to the next screenline). A compressed storage format allows some programs to be stored in fewer bytes of memory than in Level I. Level II is stored in 12K of Read-Only Memory, and comes with a comprehensive reference manual.

Disk BASIC

The TRSDOS operating system includes the software and input/output functions needed to operate the TRS-80 Disk System. TRSDOS allows vast file storage space, expanded file manipulations, and much quicker access time than you get with tape storage. Disk BASIC allows you to access files either randomly or sequentially, and programs may be stored in BASIC as ASCII or in compressed format files to save storage space.

Radio Shack’s Disk BASIC is a further extension of the Level II language. A few of Disk BASIC’s extension commands are DEF FN – allows userdefined functions. HEX CONSTANTS – allows you to enter hexadecimal and octal constants by preceding them with “&H” or “&”, and TIME$ – returns date and time as a text string.

File commands include CLOSE – closes a file which is currently open, LOAD-loads a BASIC program from disk into memory. MERGE – combines a BASIC program with another program currently in memory. OPEN – opens a file for use. This command specifies sequential/random input or output, the file number, and file name. SAVE-saves a BASIC program onto disk. (You can CLOAD a tape program, then easily put it on disk.)

Base System Hardware Specifications

Are there really 4 revisions to the expansion interface connection? (Answer by Mike Yetsko)

The problem:

In the original design, the Model I CPU generated all the timing signals to the memory. That’s the logical thing to do, right? I mean, it’s the CPU. Unfortunately this led to problems. Specifically with the way RAS*, MUX, and CAS* timing finally worked.

16K RAM chips need 14 address lines. Plus other control lines. How do they all jam onto that little chip? They do it by dividing the addresses into two batches. Think of the RAM as a ruler with 14 divisions on it. You go to the address and there it is. But that’s too many pins. So instead think of the address like a Bingo card, only 7×7 instead of 5×5. You have a row and a column. In the TRS-80 the signal RAS* means the row of the address is sent to the memory, and CAS* means the column is sent the the memory. That’s fine for the memory, but how do you tell the circuits in the computer to switch? That’s what the MUX signal is for. So to access memory the MUX get set in the first state to provide the first 7 bits and the signal RAS* tells the RAM chip to use those 7 bits. Then the MUX set to the second state to tell the circuitry to provide the next 7 bits and then the CAS* goes low to tell the RAM here’s the rest of the address.

You can imagine the timing for all that. Especially coming over cable from the CPU unit to the EI. (Not to mention there’s memory refresh going on that uses the RAS* signal)

Expansion Interface Connection Rev 1:

Expansion Interface Connection Rev 2:

Actually, there were two versions of the buffered EI cable. If a customer had a ‘bus master’ device that took control and did DMA, the device couldn’t ‘back channel’ through the buffered EI cable. So upon request Tandy provided a Buffered EI cable with a pre-buffer ‘tab’. Instead of connecting your device to the expansion port on the side of the EI, you connected it to the tab on the special buffered EI cable. These were available free upon request. The only device Tandy sold that needed this device was the Screen Printer (nick-named the ‘Scream Printer’ by techs).

Expansion interfaces with the buffered cable but without the Rev 3 modification are fairly rare; they lasted only a short time before Radio Shack moved to Rev 3.

Ian Mavric currently sells an updated buffered cable for those who might need one called NewBuff.

Expansion Interface Connection Rev 3:

Expansion Interface Connection Rev 4 (Expansion Interface v2):

Tandy eventually redesigned the EI so that it did NOT use the RAS*, MUX, and CAS* signals. It did this by generating them on the EI pcb itself with a DDU chip. (a digital delay line) This was VERY effective and negated the need for a buffered EI cable so Tandy went back to the sheilded stiff cable.

Unfortunately, expansion Interfaces which generated their own signals were, unfortunately, not comaptible with “as is” speedup kits.

But, EIs were out there in both versions, so the factory production of CPUs contained the DIN cable since you didn’t know in advance which version of the EI it would be attached to.

Parts:

Computer

It isn’t clear how many of these units were ever sold. They were basically 16K chips that were tested or ‘high’ or ‘low’ half (i.e., defective). It is rumored that Radio Shack gave anyone who got one a free upgrade to 16K. Mike Yetsko says he definitely had upgrade instructions for when they came in. It is also believed that the catalog number for the “system” (with Monitor and Cassette) was 26-1052.

It isn’t clear that any of these units were ever sold. Tandy figured out they were not the greatest when dealing with the Level I, and may never have built any Level II’s this way. It is also believed that the catalog number for the “system” (with Monitor and Cassette) was 26-1054.

This Model I Level II was produced by Tokyo Electric Co. The board layout is different. More information on this can be found on page 71 of This TRS8Bit Newsletter.

For more technical applications, the “Engineer” system combines powerful level II with 16K of RAM. The new Printer Interface cable allows direct connection of the Quick Printer to TRS-80’s bus connection, without using the Expansion Interface. Quick Printer provides 80-column hard copy and program listings. The Space-Save holds the entire system and provides the user with ample work space.

Mini-disk for expanded language, fast data handling, and approximately 49,900 bytes of user disk storage space. Quick Printer provides 80-column hard copy and prorgam listings. System Desk holds the entire system with plenty of work space left over.

Two mini-disk units give user approximately 135,600 bytes of disk storage. Virtually all TRS-80 disk-based business software requires this as a minimum system. Applications include general ledger, payroll, disk mail list, and more. Line Printer II adds real versatility and convenience to this system, without taking up a lot of work space.

Approximately 135,600 bytes of disk storage space from the two mini-disk systems. Tractor feed line printer uses fanfold paper with feed holes in the margins and will produce up to 5 carbon copies. The System Desk has recessed spaces for the Expansion Interface and keybaord with interconnecting wiring concealed. Line printer stand leaves more desk space.

Optional Hardware – Expansion

Increases TRS-80’s Internal Memory. The TRS-80 is designed for easy upgrading to a full 16K of RAM memory inside the keyboard unit. Your nearest Radio Shack store can arrange for the exchange of your 4K for 16K chips and add the keypad.

This mythical item was to upgrade a 8K TRS-80 to 16K. It was up to the tech to install it as either high or low. It could not be expanded to more memory.

Quality lower case for your Model I display and compatible printer. “Driver” tape included. NOTE: Some non-Radio Shack software will not work with this kit installed. Not intended for use with programs written in upper case format.

When you’ve mastered the Level I programming language, you can move up to higher computing power with Level II. Conversion is easy – we simply exchange the ROM chips in your TRS-80 for chips containing Level II. Your local Radio Shack store can arrange for the exchange. Incorporate Level II into your 4K or 16K RAM Level I TRS-80.

The Expansion Interface measures 4 1/2 x 16 1/2 x 8″ and is designed to sit directly under the video monitor acting as a base for it. The TRS-80’s power supply module, and an identical one for the interface, are housed inside the interface enclosure. Space is also provided for our optional RS-232-C Serial Interface Board.

A cable approximately 6″ long connects the interface to the TRS-80 bus connector. The interface provides output connectors for our TRS-80 printers, disk drives, dual cassette recorders, and an RS-232-C serial port, as well as an extension of the TRS-80 bus, the controller for the electronic circuit needed to install up to four TRS-80 Mini Disk drives, a printer and dual cassette recorders are an integral part of the Expansion Interface, as are the provisions for an extra 16K or 32K of optional RAM. The printer output port is a standard Centronics parallel circuit. This parallel port and our RS-232-C serial port allow connection of a variety of peripheral devices. Pin-out information is provided in the owner’s manual. Each requires 120VAC, 60Hz, 50 watts. U.L. listed.

With the all new Double-Density Disk Operating System, use advanced features and gain increased disk capacity with your current disk drives. With 35-track drives, disk capacity per diskette is increased from 84,000 to 152,000 characters after noemal normal system information. With a 40-track drive, formatted disk capacity is a full 184.000 characters, 737,000 characters with four 40-track drives. COPY moves flles from single-density to double-density format or from double-denslty to single-density. In addition to expanding TRSDOS to include new features, we have added most of Model III’s Disk BASIC enhancements as well. This includes full suppord for variable logical record lengths, and a series of CMD functions that sort strings, cross-reference string variables, delete spaces, and much more. Since our Double-Density TRSDOS contains manu new features, modification of some existing software may be required for use with double density. Even though most BASIC programs and many machine-language programs will run “as is” in Double-Density TRSDOS, Radio Shack applications software is not available or supported for double density operation. Kit includes operating system manual, adapter, and Double-Density TRSDOS operating system diskette. Price does not include required installation.

Optional Hardware – Storage

Each of the diskette’s 35 tracks consists of ten 256-byte sectors. Certain system information and a directory are required on each diskette, leaving 85,760 bytes of space available (each) on the second, third, and fourth drive.

A 13,000-byte program which takes 3 1/2 minutes to load from cassette tape (Level II) will load in less than 20 seconds from disk. And you may read information one file after the other (sequential), or go directly to any sector without reading the preceding files (random).

The system diskette containing TRSDOS and DISK BASIC must always be in your first drive unit. TRSDOS allows you to copy a diskette (BACKUP), even in a one drive system.

Specifications: Disk Format: 35 Tracks; 10 Sectors per Track; 256 Bytes per Sector; 89,600 Bytes per Diskette. Disk Size: 5 1/4″ floppy disk. Data Transfer Rate: 12,500 bytes-per-second. Disk Speed: 300 RPM. Latency: 100 mS (average). Track Access Time: 200 mS average, 600 mS to cross all 35 tracks. Average Backup Time: 1:10 minutes (including formatting). Memory Usage: TRSDOS, 4.2K RAM; DISK BASIC, 5.8K RAM. Power: 120VAC, 60 Hz, 35 watts, U.L Listed. Size: 6 1/2 x 3 1/2 x 13 1/4″

Store over 1000 different files per disk system or create files as large as the available space. The directory is alphabetized to make locating and accessing files quick. High-level communication is available through an advanced communication package that allows direct downloading to disk. A print spooler is included, too. The Job Control Language allows you to compile and later execute a predefined series of commands, including screen and audio alerts, conditionals, and user interaction to make many large scale operations virtually automatic. BACKUP, in addition to ordinary backup functions, permits backing up only those files that have been modified, or modified in certain date ranges, or even those that do or do not already exist on the destination disk. When backing up from hard disk to diskettes, the system will span a large file across multiple diskettes and allow easy identification of diskettes when recreating a file on the hard disk. Other features include keyboard typeahead for fast data entry, a versatile printer output formatting program, key redefinition, and more. Extensive user’s manual included. U.L. listed.

Optional Hardware – Misc

Computer voice recognition is a new field, and not fully developed, but here’s your chance to experiment with this exciting new technology. Level II required.

Place this unique instrument on a map, chart, or plan of any size. Works with an 11×17″ area. Swivel head allows operation in vertical plane. Input coordinates quickly, easily to your computer. Measure areas, lengths, distances and more. Point and continuous modes. Includes software for basic applications. U.L. Listed.

The system requires a Model I “host” computer equipped with at least one Mini-Disk drive. Student stations should have Level II BASIC. Network I Controllers can be cascaded to connect more stations. Includes cables. Maximum distance to student station is 30 feet. For Model I and Model III TRS-80’s at 500 baud. U.L. Listed.

RSC-12
Allows easy management of student programs. You can simultaneously load a program into all 16 student systems at either 500 or 1500 baud, depending on the TRS-80 computersused. With optional printer connected to host computer, student programs can be loaded into the host and printed out. Use with Model I/III/4 as host and student stations, or with Color Computers as host and student stations. The Network 2 can be used to transfer ASCII files with Model 100 student stations and either a Model 100 or a Model 4 host. Controllers can be cascaded to connect more stations.

Has a built-in real time clock and a switch permits normal cassette operation. Software included. 4K Level I, Level II or Model III BASIC required. U.L. listed.

Optional Hardware – Modem/RS-232

All you do is plug the power cord into a wall socket, the line cord into the phone jack and the connecting cable to our RS232C-equipped computer. It’s always in “Auto Answer,” so that if a host computer calls you (and your computer is properly configured), you can begin receiving information automatically. The modem automatically adjusts to the incoming baud rate. To originate, you just set the baud rate to match the host or service, run your communication software package, and place the call. And you can upgrade your DC-1200 for automatic origination.

Specifications: Data Rate: 0-300-baud asynchronous; 1200-baud asynchronous or synchronos. Operating Mode: Full or half-duplex, all speeds; automatic answer, manual originate. Line Signals: Low Speed – frequency shift keying; High Speed – differential phase-shift keying. Compatibility: Low Speed – Bell 103/113; High Speed – Bell 212A. Sensitivity: -45 dBm. Dimensions: 1-3/4 x 6-3/8 x 11-1/4″. Power: U.L. listed 120VAC, 60 Hz power module. FCC registered. Note: DC-1200 not for multi-line use without optional extra controller. Use only with Bell-compatible equipment.

To make your DC-1200 high-speed modem even more useful and versatile, add this handy accessory module. It allows the DC-1200 to automatically dial, as well as answer the phone (with proper computer configuration). This means your computer can operate unattended during low-rate night hours. Plug-in module is a printed circuit board. Installation required (not included).

The RS-232-C board mounts inside our Expanasion Interface. A cable is provided for connection to external equipment such as Radio Shack’s Telephone Interface or perhaps your own serial line printer. Included is a comprehensive user’s manual and a cassette tape program which allows the TRS-80 to act as an interactive terminal for communication with a remote timesharing computer.

Baud Rate: Switch selectible in 8 steps from 110 to 9600 baud. Software contrallable in 16 steps from 50 to 19,200 baud. Stop Bits: Selectable 1 or 2. Word Length: Selectable 5 to 8 bits. Data In/Data Out Ports: Switch reversible. Logic State Sensing: Clear to end, Data set ready, Carrier Detect, Ring Indicator. Software Controllable Outputs: Data Terminal Ready, Request To Send. Software control: All functions except Data In/Data Out reversing are fully software controllable.

This Radio Shack coupler converts a serial stream of data from the TRS-80 RS-232-C interface into selective audio tones which are then transmitted over standard telephone lines. It can also reverse the process, decoding selective audio tones and feeding them into the TRS-80 throughthe RS-232-C interface. (The RS-232-C allows the TRS-80 to communicate with the outside world via a 2-wire connection, but with electrical signals. Since electrical signals cannot be sent over a voice telephone line, the Telephone Interface converts those signals to audio tones so that the connection can be made over long distances via telephone.) The TRS-80 Telephone Interface I operates in the “originate only” mode, meaning that it can send information to other hardware. It is capable of “two-way communication” only with another computer system having ‘originate and answer” capabilities.

Specifications: Baud Rate: 300 baud. Mode: Originate only, half or full duplex. Carrier Detection Level: -40 dbm. Transmit Level: -17 dbm at 1070 Hz. Power Requirement: 120VAC, 60 Hz, 5 Watts. U.L. listed.

It’s very simple to operate. Just dial the phone number at the location of the TRS-80 you desire to communicate with; after the connection is made, each telephone handset is placed on its interface. Now you’re ready to receive and transmit data. Requires RS-232 Serial Interface Card, Expansion Interface, RS-232 Conununications Package and Level II. Adds versatility to your TRS-80.

Specifications: Baud Rate: Up to 300. Mode: Originate and Answer, full or half duplex. Receive Sensitivity: -45 dBm. Power Requirement: U.L. listed 120-volt AC power module. Size: 2-3/8 x 4-3/4 x 10-1/4″.

Specifications: Baud Rate: 300. Modes: Compatible Bell 103 Ans/Orig modes. Full duplex. Sensitivity: -43 dBm (orig), -48 dBm (ans). Connectors: DB25 and 4-pin DIN. Power Requirement: U.L. listed 120-volt AC power module. Size: 2 x 6-1/2 x 7-1/2″. Not for multi-line use.

Specifications: Baud Rate: 300. Mode: Originate and answer, full or half duplex. Receive Sensitivity: 45 dBm. Dial System: Rotary or tone. Power Requirement: U.L. listed 120-volt AC power module. Size: 2 x 6-1/2 x 7-1/2″. Not for multi-line use.

Allows direct-connect modems to be used with multi-line phones.

Optional Hardware – Furniture (Non-Printer)

Computer Reference Books

How to use print codes and other special features. Explains dot-addressable graphics. Includes BASIC programming examples.

January thru December, 1981 bound in one volume.

January thru December, 1982 bound in one volume.

Introduces the basics of computer literacy to junior and senior high school students using easy-to-understand approach. Includes teacher’s guide with lesson plans, student activity spirit masters, four wall charts and 80-frame filmstrip with audio cassette. Computer not required.

This informative booklet describes what microcomputers are and how they can be used in classrooms and for administrative purposes. Discusses costs, courseware and other related subjects that are of special concern to the educator.

Informative package to help secondary students explore computer-related careers. Covers major computer career areas and specific jobs within selected areas. Includes teacher’s guide, 30 student manuals, narrated film strip, eight spirit masters, and colorful wall chart.

A comprehensive, illustrated “owner’s manual” for Model II users. (Included with all Model II systems.)

Description of the basic means of electronic communications. 256 pages.

Self-study Level I BASIC for the TRS-80 Model I and III. Informative self-instruction course with lots of examples. 351 pages.

Exciting and challenging games for the Level 11 TRS-80. 152 pages.

Includes finance, automobile-related, kitchen helpmates, tutorial, recreation, more. 330 pages.

Software (Ordered by Catalog Number)

Finds facts on file that match “key-words” in your question. A “global search” even finds the “most similar” information when there’s not an exact match. (32K 1 -Disk).

Convert field measurements into final dimensions and coordinates (16K Level II or Model III BASIC req’d)

Provides trend change indications for shot, medium and long term periods based on formulas used by professionals. Maintains portfolio for stocks of your choice. Provides trend recognition aid, not investment counsel.

Selective printing from one of seven key fields. Approx. 600 names per data diskette, or 200 names on system diskette. 16K Disk.

Foundation and structural cost estimating for contractors. Calculates material requirements, labor component, productivity and waste.

Control over fixed asset depreciation. 32K Disk.

Attorneys, CPAs and Job Contractors. 750 clients 1250 charges per month. Up to 26 user-defined charge codes, up to 5 partners with different rates.

Enter and edit text on video screen, save text on disk, output formatted copy to printer. Buffered input for high speed typing without dropouts. Stop tabs, horizontal and vertical centering, formatted headers and footers, automatic page numbering, block manipulation and more.

Ellwood analysis, overall capitalization rate, graphic analysis, sensitivity analysis.

Programs for cash flow and depreciation.

Building development, Monte Carlo time trend, decision tree analysis.

Obtain 15 digit accuracy with sine, cosine, arctangent, natural logarithm, exponential and square root functions.

Analyze data and forecast trends. Includes random sample, histogram, frequency distribution, regression and much more.

Includes: Student Guide, Teacher Guide, Algebra I, Program World, Level II BASIC Course Part I.

Classroom management system designed to assist teachers with student personal information, grade processing and averaging. Up to 35 students.

Investigations in analyzing equations and plotting their respective graphs through demonstrations of plotting functions and plotting polar and parametric equations.

Poses graph-related questions or simulations relating to rectilinear motion including position, speed, displacement and acceleration concepts.

Plots and analyzes data pairs input by student.

Includes two games! Destroy wave alter wave of alien space ships in Cosmic Fighter. Avoid the space rocks and rescue the stranded astronauts on a distant planet in Meteor Mission 2. Optional sound effects.

Standard Zilog Mnemonics for assembly language combined with the convenience of a text editor. For advanced programmers. Cassette only.

Self-paced course teaches Level I BASIC for TRS-80. 4 tapes

Create beautiful graphics with easy-to-use BASIC commands. Requires graphics-mode printer.

Textbook with exercises.

INKEY$, ASCII set, graphics, cassette data files, more.

Library and utility commands, troubleshooting, error messages, more.

Macro-assembler, linking loader, editor, cross-reference.

Explores fundamentals through 14 investigations. Graphs and computes areas of functions.

Generates problems with emphasis on straight lines and conic sections.

Six laboratory experiment simulations on Kinetic Theory, Charles’ Law, Boyle’s Law, Titration, Conductivity and Solubility. Students control variables in experiments in order to see changing results. Each package includes an instructor’s manual and 25 student experiment books.

Definitions, examples, and exercises on constructive or computational aspects of number theory concepts.

Generates problems related tos imple matrix algebra.

Practice in coefficient and equation recognition, discriminant evaluation, type of roots, more.

For use with TRS-80 Chemistry Lab, Vol. I

Training course designed to help educators create their own lessons using TRS-80 AUTHOR I. Introduces AUTHOR I concepts. Educators are guided through actual lesson creation using text, graphics and special characters.

Presents lessons that have been created using TRS-80 AUTHOR I. Printed report includes scores and timings. Not required if you have TRS-80 Author I).

Package of 10