Tandy Color Computer 3 (CoCo 3)

The Color Computer 3 was announced on July 30, 1986 by Tandy. It came with 128 kB of RAM, which could be upgraded to 512 kB. The keyboard surround and cartridge door plastic were changed from black to grey. The keyboard layout was revised, putting the arrow keys in a diamond configuration and adding CTRL, ALT, F1 and F2 keys. It sold in Radio Shack stores and Tandy Computer Centers for $219.95.

The CoCo 3 was compatible with most older software and CoCo 2 peripherals. Taking the place of the graphics and memory hardware in the CoCo 1 and 2 was an application-specific integrated circuit called the "GIME" (Graphics Interrupt Memory Enhancement) chip. The GIME also provided additional features:

  • Output to a composite video monitor or analog RGB monitor, in addition to the CoCo 1 and 2's TV output. This did much to improve the clarity of its output.
  • A paged memory management unit broke up the 6809's 64 kB address space into 8 × 8 kB chunks. Although these chunks were considered to be too large by many programmers, the scheme would later allow third party RAM upgrades of up to 2 MB (256 × 8 kB).
  • Text display with real lowercase at 32, 40, 64, or 80 characters per line and between 16 and 24 lines per screen.
  • Text character attributes, including 8 foreground and 8 background colors, underline, and blink.
  • New graphics resolutions of 160, 256, 320 or 640 pixels wide by 192 to 225 lines.
  • Up to 16 simultaneous colors from a palette of 64.

Previous versions of the CoCo ROM had been licensed from Microsoft, but by this time Microsoft was not interested in extending the code further. Instead, Microware provided extensions to Extended Color BASIC to support the new display modes. In order to not violate the spirit of the licensing agreement between Microsoft and Tandy, Microsoft's unmodified BASIC software was loaded in the CoCo 3's ROM. Upon startup, the ROM is copied to RAM and then patched by Microware's code. Although this was a clever way of adding features to BASIC, it was not without some flaws: the patched code had several bugs, and support for many of the new hardware features was incomplete.

Manufacturer: Tandy
Date: 30th July 1986

Other Systems Related To Tandy Color Computer 3 (CoCo 3):

Item Manufacturer Date
Tandy TV Scoreboard Tandy 1976
TRS-80 Microcomputer System Model 1 Level 1 Radio Shack - Tandy 1977
TRS-80 Color Computer Tandy 1980
TRS-80 Model 100 Portable Computer Tandy Radio Shack 1983
Tandy 102 Portable Computer Tandy Radio Shack 1983
TRS-80 Colour Computer 2 Radio Shack Tandy 1983
Tandy TRS-80 Model IV Tandy 1983
TRS-80 Model 102 Portable Computer Tandy Radio Shack 1983
Tandy 1000 EX Personal Computer Tandy December 1986
Tandy 1400 Professional Computer LT Tandy 1987
Tandy 1000 HX Personal Computer Tandy 1987
Tandy 1100FD Laptop Computer Tandy Radio Shack November 1989

This exhibit has a reference ID of CH46843. Please quote this reference ID in any communication with the Centre for Computing History.

 

Tandy Color Computer 3 (CoCo 3)


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