The TRS-80 Model I, or just TRS-80 Microcomputer System as shown on the computer itself, was introduced in August 1977. It was one of the first low cost microcomputers available to the general public in large numbers, listing for $600 for a 4K machine. Given the fact that it was distributed through Radio Shack stores, its distribution network was already in place and quite large. The initial production run sold out in less than a month, and it took almost a year for Radio Shack to catch up with the demand. Radio Shack sold 100,000 TRS‑80 computers in 1978, over four times its nearest competitor. According to Tandy's website, more than 200,000 TRS-80 computers were sold from 1977 to 1981.

The machine initially came with 4K of RAM and included Level I BASIC and later was upgraded to 16K of RAM with the addition of a numeric keypad to the keyboard and Level II BASIC. There were four versions available; Level I with 4K RAM (26-1001), Level I with 16K RAM (26-1003), Level II with 4K RAM (26-1004), and Level II with 16K RAM (26-1006). Each came with a 12-inch video monitor, a battery/AC cassette recorder, a power supply and a two-game cassette.

The computer ran a Zilog Z80 at 1.77 MHz. The only means of storage was a cassette recorder. Unfortunately, its image soon started to be tarnished by problems caused by issues such as quirky connections between the computer and its external expansion chassis, quickly earning it the nickname 'Trash-80'. One major drawback of the original system was the massive RF interference it caused in surrounding electronics. Stricter FCC regulations on interference led to the Model I's replacement by the Model III. Despite these problems, the machine gained quite a following and was to be the first in a long line of computers sold through Radio Shack stores. It was followed by the TRS-80 Model II which was essentially the Model I and its display placed together in a single desktop enclosure.

The Expansion Interface, Tandy catalogue number 26-1140, -41, & -42, allowed the addition of up to 32K of RAM, up to 4 disk drives, serial and parallel devices.

Our model is the 26-1003 Model 1 with Level I Basic, 4K ROM, 16K RAM with Keypad CPU/KB, which together with associated manuals, Expansion Interface and Disk Drives was kindly donated by Helen Williams.

Manufacturer: Radio Shack - Tandy
Date: 1977

This exhibit has a reference ID of CH16821. Please quote this reference ID in any communication with the Centre for Computing History.