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T > TANDY RADIO SHACK  > Color Computer 3   

Tandy Radio Shack
Color Computer 3

The "TANDY Color Computer 3" followed the Color Computer 2.

The CoCo3 came with 128K RAM, an analog RGB video port, enhanced 640x192 graphics capability, a 64-color palette and much more. (All ports contained on the CoCo 1 and 2 models were also available on the CoCo3, e.g. RS-232 serial, cassette, right and left joystick and a 40-pin expansion slot.)

The built-in Language, named Disk Extended Color Basic 2.1, was a Microsoft BASIC with enhancements by Microware. It was similar to that of the CoCo2, but Microware added the commands/functions to take advantage of the higher resolution graphics and text.

The CoCo3 was upgradeable to 512 KB RAM. (After-market RAM upgrades have gone as high as 8MB, with rumors that 16MB and 32MB RAM upgrades may also be possible). A Multi-Pak (a 4-port bus expander) plugged into the Expansion Slot allowed use of controllers for floppy disk drives, hard drives (MFM, RLL, SCSI and now even IDE), multi-port true RS-232 devices, MIDI units and much much more.

As its microprocessor was still an 8 bit (strange choice when Atari and Commodore were using a 68000), it couldn't access simultaneously to the 128k (or 512k), and thus used several RAM banks which could be switched (as the Thomson TO8, or MSX 2 computers).
Unlike the CoCo and CoCo II the 3 had an interrupt controller. This did away with a lot of the timing loops used in its predecessors, and actually took some of the fun out of programming in Machine Language.

Tandy made several prototypes of a Color Computer model IV but it was never released.


Contributors: D. Francis


Michael Devenney, I am definitely interested. please E-mail me at

Monday 19th August 2019
Corey Lynch (United States)

I have a Tandy computer color 3 new in the box, never used. The outer box is in terrible condition , but the computer is unwrapped and has been never used. Anyone interested?

Saturday 12th May 2018
Michael Devenney (USA)

This was also my first computer since I owned a 2600 Atari and NES game system back in 1987. Learning basic was fun on this system with the built in color graphics. I remember bagging my parents for the floppy drive unit shortly afterwords and was able to save the basic programs and run games like Kings Quest. This was truly a revolution for the time and even had a special color monitor that could be purchased. What I was especially impressed about this system is all the expansion options that were available. When I was younger growing up I could all the options at once but being able to upgrade the system was an advantage along with having the composite video connection to get started.

One of my biggest regrets was selling my entire system for $50 USD and purchasing a 286 computer at the time. This system and the first IBM computer tough me a lot. The new generation of youth has a lot to be learned as we grew up in our generation.

Sunday 30th April 2017
Derrick Green (United States)


NAME  Color Computer 3
MANUFACTURER  Tandy Radio Shack
TYPE  Home Computer
YEAR  1986
BUILT IN LANGUAGE  Disk Extended Color Basic 2.1 (Microsoft BASIC, with enhancements by Microware)
KEYBOARD  Full-stroke keyboard
CPU  Motorola 68b09e (uses an external clock generator)
SPEED  1.79 MHz (0.89mhz under RS-DOS for compatability with FD expansion unit)
RAM  128 KB (up to 512 KB. There were 1MB and 2MB upgrade boards as well)
ROM  32 KB
TEXT MODES  32x16, 40x25, 80x25
GRAPHIC MODES  Several graphic modes, the most interesting were: 320x200 (16 col.), 640x200 (4 col.), 640x400 (4 col. if 512 KB RAM)
SOUND  See comment below
SIZE / WEIGHT  Unknown
I/O PORTS  Tape, Composite Video, analog RGB connector for use with Tandy CM-8 monitor, 2 joystick ports, cartridge slot, RS232
OS  with optional disk drive : RS-DOS, OS-9 Level 2 was also popular
PRICE  $219.95 (USA, 1986)

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