MACHINE REFERENCE

TRS-80 Color Computer

Name: TRS-80 Color Computer
Brand: Tandy Corporation (Radio Shack); Motorola designed the core chips

The TRS-80 Color Computer went on sale in September 1980 for $399, with a Motorola 6809E processor and Microsoft’s Color BASIC in ROM.

Why it matters

The CoCo was one of the few home computers built around the 6809, an unusually capable 8-bit processor, and it could run OS-9, a multitasking operating system, which very few 8-bit home computers could. It sold through Radio Shack stores and, through the CoCo 2 and CoCo 3, stayed on sale until 1991. The Dragon 32 uses the same 6809 and SAM and VDG chip set, which is why the two machines are so close.

What to check before you buy

Power it up and look for clean text. Random characters often mean a loose RAM chip, and reseating can help.
Never swap a cartridge with the power on; the 6809E can be killed that way.
Check which CoCo it is. The CoCo 3 is the most capable and usually the most expensive.
Look for the TV modulator and cables; a missing RF lead is the commonest problem on boxed units.
Ask about cassette and disk interfaces if you want to load software.

Photo: Bilby, Wikimedia Commons (CC BY 3.0)

Released

1980

RAM

4 KB, 16 KB or 32 KB (CoCo 1); 16 KB or 64 KB (CoCo 2); 128 KB or 512 KB (CoCo 3)

CPU

Motorola 6809E, 0.895 MHz (CoCo 1 and 2); the CoCo 3 runs at 0.895 or 1.79 MHz

Launch price

$399 (US)

Manufacturer

Tandy Corporation (Radio Shack); Motorola designed the core chips

Form factor

Keyboard computer with cartridge port on the side

CPU

Motorola 6809E, 0.895 MHz (CoCo 1 and 2); the CoCo 3 runs at 0.895 or 1.79 MHz

Chipset

MC6883 Synchronous Address Multiplexer (SAM) and MC6847 Video Display Generator (VDG); the CoCo 3 uses the GIME chip

RAM

4 KB, 16 KB or 32 KB (CoCo 1); 16 KB or 64 KB (CoCo 2); 128 KB or 512 KB (CoCo 3)

ROM

8 KB Microsoft Color BASIC (extended versions available)

Graphics

256 x 192 with nine colours; the CoCo 3 adds 320 x 192 in 16 colours and 640 x 192 in four

Audio

6-bit DAC and one-bit sound; an expansion cartridge can add an AY-3-8913 sound generator

Storage

Cassette; 5.25-inch floppy disk (160 KB standard, 40-track on CoCo 2 and 3)

Ports

Cartridge slot, RS-232 serial, two joystick inputs, cassette, RF output

Color BASIC in ROM; OS-9 multitasking (third-party)

PSU

External power adapter

Units sold

Unknown

Successors

CoCo 2 (1983); CoCo 3 (1986)

Garbage screen on power-up

Random characters at start-up usually point to a loose RAM chip or a damaged CPU. Reseating the RAM chips cures some cases.
CPU damage from hot cartridge swaps

The 6809E can be damaged if a cartridge is inserted or removed while the power is on.
Socket and solder problems

Poor solder joints, bent pins under sockets and shorts across the board are common causes of a machine that won't start.

1980 Tandy launches the TRS-80 Color Computer in September at $399
1983 The CoCo 2 arrives with a smaller board and a smaller RF modulator
1986 The CoCo 3 adds the GIME chip and up to 512 KB of RAM
1991 CoCo 3 production ends