TRS-80
From Retrocomputing Wiki
| TRS-80 Model I | |
|---|---|
| Manufacturer | Tandy Corporation / Radio Shack |
| Type | Home computer |
| Released | August 1977 |
| Introductory price | US$599.95 with monitor and cassette recorder |
| Discontinued | January 1981 |
| CPU | Zilog Z80 at 1.77 MHz |
| Memory | 4 KB, expandable to 48 KB |
| Storage | Cassette, 5.25-inch floppy disk via the Expansion Interface |
| Display | 64 × 16 text, 128 × 48 block graphics, monochrome |
| Sound | None (cassette port often used for sound) |
| Operating system | Level I or Level II BASIC in ROM; TRSDOS |
The TRS-80 (from Tandy/Radio Shack, Z-80 processor) is a line of computers sold by Tandy Corporation through its Radio Shack stores. This article is about the first model, later called the TRS-80 Model I, which was announced in August 1977. Because Radio Shack had thousands of stores across the United States, the TRS-80 was the easiest of the early computers to buy, and for a few years it outsold the Apple II and the Commodore PET.
[edit] History
The TRS-80 was designed by Don French, a Radio Shack buyer who had built his own computer from a kit, and Steve Leininger, an engineer hired from National Semiconductor. Tandy management was not convinced there was a market and ordered a first production run of only 3,500 machines, so that if they did not sell they could at least be used in the company's own stores. Around 10,000 orders arrived within the first month.
The computer was sold as a complete system with a monochrome monitor (a modified RCA black-and-white television) and a Radio Shack cassette recorder, for $599.95.
[edit] Hardware
The main unit contains the keyboard, the Zilog Z80 processor and 4 KB of RAM. The original ROM held Level I BASIC, a small BASIC based on Li-Chen Wang's Tiny BASIC. It was replaced in 1978 by Level II BASIC, a 12 KB Microsoft BASIC.
The video display shows 16 lines of 64 characters. There are no lower-case letters without a modification, and graphics are made from 2 × 3 blocks within each character cell, for a resolution of 128 × 48.
The Expansion Interface, which sat under the monitor, added more memory, a floppy disk controller, a printer port and a second cassette port. It was connected by a short ribbon cable and had a reputation for unreliable connections and random reboots.
[edit] Reception
The Model I was popular but had a number of problems. Keys often "bounced", producing double letters, until a software fix was released. Its cases leaked a great deal of radio interference, and when the US Federal Communications Commission introduced new rules on interference from home computers, Tandy decided to stop making the Model I rather than redesign it. It was replaced by the TRS-80 Model III in 1980.
Critics and owners sometimes called it the "Trash-80", although this was usually said with some affection.
