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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



the Tandy was my very first computer. I spent hours of fun on it. back when you had to turn the little switch from TV to computer on channel 3 back then. I wish Ii held onto it now, it''sd be fun to mess around again on it. thanks for the fun., Jack

Thursday 1st October 2015
Jack (USA)

I have uploaded scans of the system manuals, in PDF on skydrive, the Public address is$c1a7e9824022ad17$resid$C1A7E9824022AD17!732

I have some of the most common hardware manuals there too, if you are looking for another manual, most likely I have it.

The manuals are for all 3 Color Computers ( 1, 2, and 3) Schematics and repair manual included.

Please archive these manuals, I don''t know how long I will keep them there, or add them to as a direct download.

Wednesday 6th July 2011
Jorge (NY, USA)

Does anyone know if the COCO 3 FPGA project has been put into a low cost ASIC chip... i.e. a single ASIC chip Coco 3... I''m wanting to use one instead of a PIC or embedded processor ... It would be great if I could get a single chip coco 3 with the functions of the coco 3 ( Enhanced ) and the functionality of a PIC... I''d love to buy one ...

Monday 27th June 2011
Lez Anderson (England)


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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