computer science

List of TRS-80 and Tandy-branded computers

List of TRS-80 and Tandy-branded computers is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand List of TRS-80 and Tandy-branded computers rather than just read about it. In short: Tandy Corporation released several computer product lines starting in 1977, under both TRS-80 and Tandy branding. TRS-80 was a brand associated with several desktop microcomputer lines sold by Tandy Corporation through their Radio Shack and Tandy stores.

Key takeaways

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Reference excerpt

Tandy Corporation released several computer product lines starting in 1977, under both TRS-80 and Tandy branding. TRS-80 was a brand associated with several desktop microcomputer lines sold by Tandy Corporation through their Radio Shack and Tandy stores. It was first used on the original TRS-80 (later known as the Model I), one of the earliest mass-produced personal computers. However, Tandy later used the TRS-80 name on a number of different computer lines, many of which were technically unrelated to (and incompatible with) the original Model I and its replacements. In addition to these, Tandy released a number of computers using the Tandy name itself.

Original TRS-80 ("Model I") and its successors

Model I

The original TRS-80 Micro Computer System (later known as the Model I to distinguish it from successors) was launched in 1977 and- alongside the Apple II and Commodore PET- was one of the earliest mass-produced personal computers. The line won popularity with hobbyists, home users, and small-businesses. The Model I included a full-stroke QWERTY keyboard, floating-point BASIC, a monitor, and a starting price of US$600. By 1979, the TRS-80 had the largest selection of software in the microcomputer market. In July 1980 the mostly-compatible TRS-80 Model III was launched, and the original Model I was discontinued.

Model III

In July 1980 Tandy released the Model III, a mostly-compatible replacement for the Model I. Its improvements over the Model I included built-in lower case, a better keyboard, elimination of the cable spaghetti, 1500-baud cassette interface, and a faster (2.03 MHz) Z80 processor. With the introduction of the Model III, Model I production was discontinued as it did not comply with new FCC regulations as of January 1, 1981 regarding electromagnetic interference. The Model III could run about 80% of Model I software, but used an incompatible disk format. It also came with the option of integrated disk drives.

Model 4

The successor to the Model III was the Model 4. Its microprocessor was a faster Z80A 4 MHz CPU. Disk-based Model 4's had 64 KB of RAM standard; an optional bank of additional 64 KB was accessible to applications software using bank switching technology. The Model 4's new hardware features included a larger display screen with 80 columns by 24 rows, inverse video, and an internal audio speaker. Its keyboard had three function keys and a control key. It used an all-new operating system derived from the advanced Model III LDOS 5, licensed from Logical Systems, now christened TRSDOS Version 6. A more modern version of Microsoft's BASIC interpreter more closely resembled the MS-DOS GW-BASIC, featuring PC-like functionality. The Model 4 could run the industry-standard CP/M operating system without hardware modification (as was needed for the Model III). This afforded the user access to popular application software such as MicroPro's WordStar, Ashton-Tate's dBase II, and Sorcim's SuperCalc. Furthermore, the Model 4 could be booted with any Model III operating system and emulated the Model III with 100 percent compatibility. Prices started from $999 for the diskless version. Early versions of the Model 4 mainboard were designed to accept a Zilog Z800 16-bit CPU upgrade board to replace the Z80 8-bit CPU but this option was never released, as Zilog failed to bring the new CPU to market.

Business systems

Tandy 10

Tandy's first design for the business market was a desk-based computer known as the Tandy 10 Business Computer System, which was released in 1978 but quickly discontinued.

TRS-80 Model II and successors

Model II

In October 1979 Tandy began shipping the TRS-80 Model II, which was targeted to the small-business market. It was not an upgrade of the Model I, but an entirely different system with state-of-the-art hardware and numerous features not found in the primitive Model I. The Model II was not compatible with the Model I and never had the same breadth of available software. This was somewhat mitigated by the availability of the CP/M from third parties.

Model 12 The Model II was replaced in 1982 by the TRS-80 Model 12. This was essentially a Model 16B (described below) without the Motorola processor, and could be upgraded to a Model 16B.

Model 16, Model 16B, and Tandy 6000

In February 1982, Tandy released the TRS-80 Model 16, as the follow-on to the Model II; an upgrade kit was available for Model II systems. The Model 16 adds a 6 MHz, 16-bit Motorola 68000 processor and memory card. The Model 16 sold poorly at first and was reliant on existing Model II software early on. In early 1983, Tandy switched from TRSDOS-16 to Xenix. The Model 16 evolved into the Model 16B with 256 KB in July 1983, and later the Tandy 6000, gaining an internal hard drive along the way and switching to an 8 MHz 68000. The 16B was the most popular Unix computer in 1984, with almost 40,000 units sold.

Other systems

Color Computers

Tandy also produced the TRS-80 Color Computer, based on the Motorola 6809 processor. This machine was clearly aimed at the home market, where the Model II and above were sold as business machines. It competed directly with the Commodore 64, Apple II, and Atari 8-bit computers. OS-9, a multitasking, multi-user operating system was supplied for this machine.

Model 100 line

In addition to the above, Tandy produced the TRS-80 Model 100 series of laptop computers. This series comprised the TRS-80 Model 100, Tandy 102, Tandy 200 and Tandy 600. The Model 100 was designed by the Japanese company Kyocera with software written by Microsoft. (The Model 100 firmware was the last Microsoft product to which Bill Gates was a major code contributor.) It was also marketed as the Micro Executive Workstation (MEWS). The Model 100 had an internal 300 baud modem, built-in BASIC, and a limited text editor. It was possible to use the Model 100 with most phones in the world with the use of an optional acoustic coupler that fit over a standard telephone handset. The combination of the acoustic coupler, the machine's outstanding battery life (it could be used for days on a set of 4 AA cells), and its simple text editor made the Model 100/102 popular with journalists in the early 1980s. The Model 100 line also had an optional bar code reader, serial/RS-232 floppy drive and a Cassette interface. Also available as an option to the Model 100 was an external expansion unit supporting video and a 51⁄4" disk drive, connected via the 40-pin expansion port in the bottom of the unit.

Tandy 200

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Illustrations

Worked examples

Example 1 — a first encounter with List of TRS-80 and Tandy-branded computers

Start with the simplest possible case. Write down what List of TRS-80 and Tandy-branded computers claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to List of TRS-80 and Tandy-branded computers before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about List of TRS-80 and Tandy-branded computers ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of List of TRS-80 and Tandy-branded computers

In research: List of TRS-80 and Tandy-branded computers appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses List of TRS-80 and Tandy-branded computers in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: List of TRS-80 and Tandy-branded computers is common in secondary-school and first-year university syllabi. It links to neighbouring topics Lists of computer hardware, Microcomputers, RadioShack, so understanding it makes those chapters shorter.
In everyday life: Look for List of TRS-80 and Tandy-branded computers outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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Frequently asked questions

What is List of TRS-80 and Tandy-branded computers in simple terms?

Why does List of TRS-80 and Tandy-branded computers matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study List of TRS-80 and Tandy-branded computers?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on List of TRS-80 and Tandy-branded computers.