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

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

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