KB10007: Tandy Color Computer (CoCo) Overview

Color Computer 1

The Color Computer, or CoCo, launched in 1980 through Radio Shack. Despite the TRS-80 name, it used a Motorola 6809E processor—not the Z80 of other TRS-80 models. The original had 4K or 16K RAM (expandable to 32K or 64K), 8K of Microsoft Color BASIC in ROM, and hooked to a TV for display. Graphics ran at 192×128 in a handful of colors. The machine grew out of an experimental videotex project; Tandy adapted it into a general-purpose computer.

Color Computer 2 and 3

The CoCo 2 arrived in 1983 with a smaller case and similar internals. The CoCo 3 (1986) added more RAM, improved graphics, and a text mode with 80 columns. All three maintained strong software and hardware compatibility. The line was discontinued in 1991.

Software and Expansion

Color BASIC stayed in ROM across the line. OS-9, a multitasking Unix-like system, was available from third parties. Expansion came through the cartridge port and optional peripherals. The CoCo had a dedicated user community and remains collectible.

Common Restoration Notes

Power supplies need recapping. The 6809E and supporting chips are generally robust. Keyboard contacts can wear. The RF modulator output may need adjustment for a clear picture on modern displays. Disk drives, if present, need the usual cleaning and belt replacement. The cartridge port can accumulate corrosion; clean contacts before testing. CoCo units are often found without their original power supply; verify voltage and polarity before connecting a substitute.