The underdog of 1977 Trinity

The Story of the Tandy RadioShack
TRS-80 Model 1

In 1977, three computers came onto the market in the U.S.: the Apple II, the Commodore PET and the Tandy TRS-80. While Apple and Commodore were also noticed in Europe, Tandy remained largely unknown – unjustly, as this article proves. Author’s note: This article tells the story from the perspective of Germany.

My own Tandy TRS-80 Model 1 Level II from 1981, with Expansion Interface, Tape Recorder and externel Floppy Disk Drives.

The year 1977 is generally regarded as the “big bang” in the history of microcomputers — and certainly rightly so. Until then, computers were mainly something for companies, universities or government institutions. In 1977, many people began to realize that microcomputers could also find their way into many private households in the future. The clunky giant boxes of the past or the do-it-yourself kits for a handful of nerds now became affordable, compact and, for the first time, easy-to-use systems for the desktop.

Seemingly by chance and completely independently, three different manufacturers came onto the market in the USA in 1977 with computers that initiated this revolution: Apple, Commodore and Tandy RadioShack. This prompted Byte Magazine in its now legendary 1995 review to portray these three as the “1977 Trinity” (Link 1). In collector circles in this country, mainly the former are popular and have long since achieved cult status. Tandy RadioShack on the other hand has always remained an “underdog”. Especially in Germany, these computers are nowadays often completely unknown to many younger retrocomputer fans due to their low distribution. That’s why this article reports more about the third of the “Trinity”, the Tandy RadioShack TRS-80 Model 1 and its part in the computer revolution.

The most important product in company history

By the mid-1970s, Tandy Corporation – originally a leather goods retailer based in Fort Worth, Texas – was already a successful company in the US. Through its merger with RadioShack, Tandy took over 3,000 electronics stores and their range of electronic components and electronic equipment. RadioShack, which in Germany was comparable to Conrad or Völkner, profited greatly from the CB radio boom and the drop in prices for radio, hi-fi and television equipment. Since the advent of transistors, the business with electronic devices and components experienced a boom. Don French, a buyer at Tandy at the time, was very inspired by the MITS Altair (Link 2). Based on it, he began to develop his own computer and demonstrated it to his boss John V. Roach, the head of the production department. Roach was less impressed with the draft, but even more impressed with the idea that Tandy could also sell his own computer kit. Then, on a visit to National Semiconductors in 1976, the two met Steve Leininger, a member of the Homebrew Computer Club (Link 3). He inspired them with his expertise on the SC/MP microprocessor (Link 4). In a roundabout way, they were able to get Steve Leininger to help Tandy move forward with the idea of building their own computer. However, Leininger convinced them to develop a finished microcomputer right away instead of a kit. That way, he said, Tandy could reach customers who had no soldering experience.
Unfortunately, their project was initially rejected by the Tandy management because the planned computer was far above the average price of the rest of the RadioShack product range. In December 1976, however, the project was finally approved, with the proviso that great attention be paid to cost reduction. Not least because of this, the decision was made to use the less expensive Z80 8-bit CPU from Zilog (Link 5). The developers further reduced costs by not including sound, color and graphics capabilities. Furthermore, they relied on the stripped down version of Li-Chen Wang’s public domain version of Tiny BASIC. They also did not use lowercase characters in the character set and managed to fit everything into a 4 kByte ROM. At runtime, just 2 kByte of the total 4 kByte RAM were available for own programs. Don French said in an interview: “We made many decisions in the design related to keeping the cost down. We left out having upper and lower case to save $1.97 per computer. [Charles] Tandy would never have accepted a product we lost money on.” (Link 6).


According to an anecdote, during the first internal presentation of the computer at boss Charles Tandy, Tiny BASIC caused an embarrassing crash when he entered his salary of 150,000 US dollars into a small financial program. This was because Tiny BASIC could only handle signed 2-byte integers with a maximum value of 32,767. For the production version, therefore, support for floating point numbers was hastily added. This even gave an advantage over the Apple II, which did not support floating point numbers with its built-in integer BASIC. For this, the existing 16-bit integer code was replaced with a version that used 32-bit single-precision floating-point numbers. Leininger also extended the language to include input and output routines for keyboard, monitor, and cassette reading and writing. In a presentation announcing the TRS-80, Leininger said, “What we did was we went through Wang Basic again and removed about 60 percent of it completely, the integer overhead and all those things.” (Link 7). Still, Level I BASIC, as it was eventually called for the TRS-80, was extremely limited. For example, it offered only exactly two string variables, A$ and B$, and a very limited instruction set. However, Tandy considered the BASIC to be sufficient for entry-level computer novices. Tandy therefore supplied a correspondingly detailed manual, which was aimed exactly at this target group.
The motherboard contained the Z80 CPU with 1.77 MHz, 4 kByte ROM with Level I BASIC and 4 kByte RAM. There were connectors for monitor, cassette recorder and an external power supply and a connector for interface boards, for example to add a printer port. The very compact board found place in a simple, unshielded plastic case in silver “space age optics”. The case also contained a typewriter-like keyboard without a numeric keypad. In total, the development of the calculator cost just $150,000. Incidentally, the case design with the elevated shape was found again a few years later in the Commodore VIC-20 and C-64, which earned these machines the affectionate nickname “breadbox”.

German version of the Level I BASIC handbook.

Sales launch for the Christmas season

Since Tandy RadioShack could not estimate the sales potential of its own computer at all at the beginning, the company decided to produce only 3,500 units in stock for the sales launch. This was enough to supply all RadioShack stores in the country with a unit for display. If sales went wrong, the computers could at least still be used for the company’s own inventory management. A converted, portable black-and-white RCA television set, with the tuner simply omitted, served as an inexpensive monitor. A connection to a standard TV set was not intended due to the lack of an RF modulator. By the way, the TRS-80 actually owes its color scheme to the monitor. Because of the uniform design, Tandy simply took over the silver case color of the monitor. The storage medium was a portable, inexpensive cassette recorder, which RadioShack had in its own range anyway.
As early as August 3, 1977, Tandy RadioShack presented the computer in New York at a press conference and two days later at the Boston University Personal Computer Fair. The sales price at introduction was 399 US dollars for the computer in the basic configuration with 4 kByte RAM. With a 12″ monitor and cassette recorder, the system cost $599. This made it significantly cheaper than its two competitors, Apple II ($1,298) and Commodore PET ($795). Tandy’s announcement of a low-cost computer on the market generated a lot of attention. The company had not dreamed of the response from customers that followed: A total of 250,000 reservations with a down payment of 100 US dollars were received by Tandy in the following weeks. Consequently, Tandy’s 1977 annual report also called the computer “probably the most important product we have ever built in our company factory.”
Tandy’s own production capacity in Forth Worth Texas and its own distribution network through RadioShack stores did enable it to increase production and sales figures in the short term. But this did not come close to serving the long waiting lists, and it initially led to long delivery times. Nevertheless, it resulted in a lead over the competition from Commodore, who announced their PET several months before the TRS-80, but then had severe delays until delivery. By the way, the TRS-80 was the best selling of the three computers until it was discontinued in 1981 (Link 8).


Shortly after the first computers were delivered, support requests began to increase: TVs and radios were disturbed when the computer stood near them. The interaction with the cassette drive was very clumsy and prone to crashes. The monitor image was not particularly stable and tended to flicker slightly. The connection to the expansion interface was also a nuisance and a frequent cause of crashes. With Level II BASIC, the famous “key bounce” problem was encountered: When a key was pressed, several characters were displayed on the screen if the contacts became dirty (Link 9).
Such and similar stability problems gave the TRS-80 the inglorious name “TRASH-80” and the reputation of not being suitable for professional work. Its fans later affectionately called it “Trashy” for this reason.
At least for the very limited Level I BASIC, Tandy was already planning an improvement for the market launch. The young company Microsoft could be won to develop an extended BASIC version. This Level II BASIC as ROM extension could be retrofitted by the RadioShack store around the corner as a small add-on board. Level II BASIC was the urgently needed extension to make the TRS-80 also fit for more professional business applications. Only with this, for example, the support for the Expansion Interface and – together with Disk BASIC – the access to floppy drives became possible.

Source of inspiration

In fact, due to the wide distribution of the TRS-80 in North America, a large market for expansions quickly developed, which was served by Tandy itself, but also by third-party manufacturers. One of the most important expansions was certainly the Expansion Interface. Because the keyboard unit had only a single board connector, this additional connector box was absolutely needed. In addition to a parallel and serial port, it offered a controller and connection for up to four 5.25″ floppy disk drives of the type Shugart SA-400s 35 (35 tracks, single density with a formatted capacity of 85 kByte) and a memory expansion of 32 kByte. Thus, the TRS-80 could be expanded to a total of 48 kByte RAM and thus to a quite powerful system. With the time some disk operating systems like TRSDOS, LDOS, or NewDOS/80 established themselves for it, which did not have to fear the comparison to CP/M regarding the achievement range. CP/M, the operating system standard until the middle of the 1980s, ran on the Model I unfortunately only with a hardware modification like the so-called Omikron Mapper. CP/M expected the RAM start address at 0000h, but there was already the ROM of the TRS. Only with the Model IV there was finally an unrestricted CP/M support (Link 10).
Nevertheless, a wide range of professional application software like VisiCalc for TRSDOS, word processors like Zorlof and programming languages like Fortran, Cobol or Pascal were available. But small startups also developed quite popular software for the TRS-80, most notably Lazywriter (Link 11) by David and Theresa Welsh. The software was born out of the idea to create an inexpensive yet powerful word processor for home and small business use, which was at the same time more comfortable than e.g. the very rudimentary Scripsit (Link 12) that RadioShack included for the TRS. If you are interested, you can browse through the RadioShack computer catalogs (link 13) published since 1977. These catalogs show the development history of the model range and the many peripherals such as acoustic couplers, modems, printers, voice synthesizers and so on.

Let the show begin

Despite its limited graphics and sound capabilities, there were also many games for the “Trashy”. Thus, the often lovingly programmed games with their crude block graphics exude a charm all their own from today’s perspective. Creative game programmers even elicited sound effects from the TRS-80, which could be output as a loudspeaker replacement using a cassette recorder. A cult game especially for the TRS-80 is “Dancing Demon” by Leo Christopherson. The game shows a tap-dancing devil on a stage, who jumps and dances according to a choreography, making clicking noises. The choreography can be freely “programmed” by the player. In addition, many arcade classics were ported, including Frogger, Galaxy Invasion and Cosmic Fighter (Space Invaders clones), Donkey Kong, Scarfman (PacMan clone), Sea Dragon or StarTrek. But there were also some special titles that were first available on the TRS-80, like Scott Adams’ Text Adventure series and Leo Christopherson’s games Bee Wary or Android Nim with their sometimes very particular game principles.

The almost abrupt end

Despite continued customer demand, RadioShack ceased production on January 1, 1981 – just three and a half years after its introduction. The culprit was not falling customer demand, but new radio interference regulations from the United States Federal Communications Commission (FCC) that went into effect that day. Since its introduction, the Model I had been known and notorious for its interference with radio and television equipment. This had a lot to do with its modular design, but also with the complete lack of shielding on the housings. Thus, starting in 1981, the Model I was no longer allowed to be sold in the USA. For the Expansion Interface, Tandy still got a delay until the end of 1981, which meant that 30,000 units could still be sold (link 14).
However, this did not automatically mean the end for other countries. Which leads us to the next small and not completely verifiable anecdote: Tandy planned to move production of the Model I to TEC (Tokyo Electric Company) in Japan as early as 1979 to make room for the successor, the Model III, at its own Texas plant. The original plan was to sell Model I and Model III in parallel. However, the FCC put a stop to this. Because the retrofitting of a shielding for the Model I did not appear to be profitable, it was finally decided to stop production completely. However, Tandy forgot to inform the contract manufacturer TEC in Japan, where production was still going on. When the mistake was discovered, 25,000 devices had already been produced on stock (link 15). Tandy therefore decided without further ado to sell the computers outside the USA. As a result, these TEC-produced models also appeared on the market more often in Germany.

Inside of the Expansion Interface. To the right, you can see the external power supplies housed within the case.

From trash to treasure

The TRS-80 Model I Level II from the author’s collection is also from TEC from the production year 1981 and has a completely revised board design (Catalog No. 26-1006A). With already 16 kByte RAM and a much improved green monitor including antireflection coating, it is already well equipped in the base. For many of its fans, this is the best version of the TRS-80 Model I ever built: Better keyboard with numeric keypad without keybounce problem and factory lowercase letter generator. Furthermore, the video synchronization was improved, so the image output is now more stable. Some chips have been replaced by newer, improved variants or their position on the board has been changed, so that the small daughterboard for the Level II ROM is no longer needed. Almost all chips come from quality manufacturers in Japan, such as the Z80 CPU, which is now produced by NEC (D780C) and is considered to be extremely robust. Unfortunately, the Japanese-produced version of the TRS-80 is very rare today, and thus highly sought after by collectors.

The community today

Due to the degree of distribution, the fan community is of course still most strongly represented in the USA today. There, for example, the annual “Tandy Assembly” (link 16) takes place in Springfield (Ohio), where everything revolves around TRS-80 computers. The first place to go on the Internet is Ira Goldklang’s website (link 17), where you can find a lot of information about hardware and software, emulators, service manuals and so on. Popular is also the TRS-80 Trash Talk (Link 18), which is streamed on YouTube every now and then. There, the veterans meet, who sometimes worked for Tandy in the past and have been taking care of their old boxes for many years. The fans also discuss new hardware expansions there. As far as modern expansions are concerned: The Talker/80 voice synthesizer board by Michael Wessel (link 19), registered in the VzEkC forum as MicrotronicHamburg, received a lot of attention in Trash Talk. It implements the original voice synthesizer from 1979 in an improved and extended form with modern hardware. Not to forget also the SepTandy series on YouTube, where many tinkering and repair videos, but also extensions like the modern hard disk replacement FreHD and graphic extensions were presented.
Also worth mentioning and recommending is the TRS8-Bit Newsletter (Link 20) in PDF format by Dusty M. It keeps the TRS-80 fans up to date about all relevant news. In the German-speaking area unfortunately no own Tandy forum could be found any more. The last forum was discontinued several years ago. That’s why the first and best German-speaking contact point for the exchange around the Trashy is our VzEkC forum (Link 21). There are quite a few TRS-80 or VideoGenie fans and Z80 knowhow can be found there anyway.

TRS-80 to try out

There is still enough information and software for download (link 22/23) on the Internet with a little search. If you just want to try out programs or games, you can use a variety of freely available emulators for Windows, Linux and Mac to dive into the world of the TRS-80. Most of them also emulate the successor models from the Z80 series. My personal favorite under Linux is the emulator trs80gp (link 24) by the Canadian George Philips, because it comes with the ROMs for many TRS-80 models and their equipment variants, offers a wide range of functions and is actively developed further. The software is also available for Windows, Mac and even the RasPi.

Distribution in Germany

The first TRS-80s were sold in Germany by the company Trommeschläger Computer GmbH (TCS) through imports from the USA. But in the early 80s, Tandy also ventured into Europe with its own computer stores, and thus into Germany as well. However, the computer stores were only opened in a few major cities and closed again as early as the mid-1980s. This did not really ensure a large distribution of Tandy computers in Germany. Nevertheless, even in some university computer rooms TRS-80 Model I could be found. Trommeschläger, however, distributed very successfully for some years the TRS-80 replicas Video Genie I/II/III of the company EACA from Hong Kong, which were software compatible to the TRS-80. Due to the bankruptcy of EACA, Trommeschläger was unfortunately also drawn into the turbulence and had to file for bankruptcy in 1985.

How it continued

On the one hand, Tandy further expanded the model range of TRS-80 and CP/M compatible systems in the 80s by also increasingly developing systems for the professional sector. However, due to the ever-increasing spread of inexpensive home computers from Commodore, Atari or Sinclair from the beginning of the 80s, Tandy also wanted to meet this market more strongly. So the manufacturer decided to launch its own home computer series. What followed was the TRS-80 Color Computer or CoCo for short. This computer series was the result of a cooperation with the chip manufacturer Motorola. The computers had a 6809E 8-bit CPU with built-in Microsoft Extended BASIC V1.1. They were already equipped with 32 or 64 kByte RAM and were not software compatible to the TRS-80. Also with the CoCo an active collector and fan community keeps up to this day. When the IBM compatible computers replaced the CP/M systems more and more, this also forced Tandy to switch to MS-DOS and Windows based systems. As late as the mid-1980s, the company was still viewed extremely positively by market analysts. Tandy had already sold 40,000 units with Xenix and Motorola 68000 processor, especially in the Unix area with the Tandy Model 16. In the meantime, “RadioShack” had long since been dropped from the name because of the “cheap image”. Until 1990/1991, Tandy was still the world’s largest contract manufacturer of personal computers. Its OEM manufacturing capabilities produced hardware for Digital Equipment Corporation, GRiD, Olivetti, AST Computer, Panasonic and others. However, due to an improper model policy, the exclusion of third-party manufacturers, and frequent incompatibilities, Tandy subsequently lost more and more market share to competitors such as DELL. In the subsequent restructuring measures, Tandy closed many of its computer stores worldwide starting in 1991 and finally sold the computer production completely to AST Computer in 1993.

From left: Color Computer 1, CoCo 2 16 kB and CoCo 2 32 kB


The Model I of the TRS-80 from 1977 is a piece of living microcomputer history from their early days and can definitely be mentioned in the same breath as its two competitors at the time, Commodore and Apple. The computer clearly deserves a place of honor in the ancestral gallery of 8-bit microcomputers. At that time, it was the cheapest entry into the world of computers for many people. Its rather small distribution in Germany does not reduce its attractiveness today. On the contrary: Since it is rather exotic at exhibitions nowadays, it often attracts attention. Its modularity allows it to be expanded into a powerful overall system by the standards of the late 1970s. The modern extensions help in the exchange with today’s PC world. Due to a still very lively community worldwide, there is therefore certainly no lack of support in the future.


My article was also published in the Retro Computer Magazine LOAD issue 9 / 2023 of the Verein zum Erhalt klassischer Computer (VzEkC) in June 2023.
It is thus subject to the Creative Commons Licence (CC-BY-NC-SA).


  1. /questions/12343/whats-the-first-use-of-the-term-1977-trinity
  3. Computer_Club
  4. Semiconductor_SC/MP
  6. wordpress/interviews/interview-with-don-french/
  7. wordpress/interviews/interview-with-steven-w-leininger/
  10. threads/trs-80-model-1-level-1-cpm.79301/
  11. trash80.htm
  15. trs8bit_year10.pdf
  22. system-80/software_archive.htm

2 thoughts on “The underdog of 1977 Trinity”

  1. Sales figures showed the Model I was the top seller of the 1977 Trinity till about 1979 when the Apple II+ overtook it. If you were in Europe, you would have thought the PET was the top seller, but the US was over 90% of the computer market at that time according to infoworld.

    1. Hi James,
      Thanks for pointing that out. My figures are based on Matthew Reed’s website, which I linked to in the article. He himself has the figures from “Personal Computer Market Share”. But there they only look at sales of the Apple II and not the Apple II+/e. Where did you get your information? Apparently it is quite hard to get valid sales figures from that time.
      In Europe and especially in Germany the situation was completely different. Here, the Commodore PET dominated far before the Apple II and even more so before the Model I. This was probably also due to the fact that Commodore managed to build up a strong distribution in Germany very soon and to produce here as well.

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