Color Computer 3

Released in July 1986, the Tandy Color Computer 3 was the final and most powerful model in the CoCo series. It retained the Motorola 6809E CPU, but added up to 512KB RAM, RGB video output, enhanced graphics modes, and compatibility with OS-9 Level II, a powerful multitasking operating system. It also introduced a new memory management unit (MMU) and faster ROM access, while preserving near-perfect compatibility with most CoCo 1 and 2 software. Though overshadowed by the rise of the IBM PC and Commodore Amiga, the CoCo 3 gained a devoted user base that kept developing for it well into the 1990s.

Notable Features

• First and only CoCo with RGB video output
• Added a Memory Management Unit (MMU) for paged memory access
• Compatible with OS-9 Level II, enabling multitasking and a graphical OS shell
• Fully backward compatible with most CoCo 1 and 2 software and hardware
• Optional high-resolution modes gave it a competitive edge for productivity

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Historical Significance

• Released just after Sinclair was acquired by Amstrad and the Amiga 1000 debuted — 1986 was a pivotal year
• One of the few 8-bit machines to support a true multitasking UNIX-like OS
• Helped keep the CoCo community alive into the 1990s with BBSes, shareware, and games
• Last Radio Shack-branded home computer not based on IBM PC-compatible hardware

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Collector's Notes

• Rarity: Moderate – still common in the wild, but boxed and upgraded 512KB units are desirable
• Desirability: Very high among retro computing fans due to OS-9 and RGB output
• Common Issues:
  • Video output (especially composite) may degrade
  • RF shielding heat buildup
  • Expansion connectors and keyboard membranes can wear out
• Display Tips: Run OS-9 Level II with a graphical shell, or games like Pac-Dude or Thexder in full color on RGB

Specifications

Technical Information
Name	Color Computer 3
Manufacturer	Tandy
Launched	Tuesday, July 1, 1986
Discontinued	1990
Launch Price	$219 USD (128KB model)
Country	United States
CPU	Motorola 6809E @ 1.79 MHz
Units Sold	~300,000–400,000
Power	Internal PSU (120V AC), improved voltage regulation over CoCo 2
Operating System	Enhanced Color BASIC, Disk BASIC, OS-9 Level IIee
Expansion	Cartridge slot, RS-232, printer, joystick, Multi-Pak Interface
Storage	Cassette interface, optional floppy disk controller
Keyboard	63-key full-travel keyboard with RESET key
Sound	1-bit internal speaker (bit-banged), compatible with earlier CoCos
Graphics	Text: 32×16 or 80×25; Graphics: up to 640×225 in monochrome or 320×225 in 4-color
Display	Composite and RGB output; up to 640×225 resolutione
ROM	32KB with Enhanced Color BASIC and Disk BASIC
RAM	128KB standard, expandable to 512KB