Tandy Color Computer 2 (CoCo 2)

Tandy Color Computer 2 (CoCo 2)

[Vin96]

The Tandy Color Computer 2 (“CoCo 2”), introduced in 1983, was renowned for its use of the powerful Motorola 6809E processor, a choice that set it apart from other home computers of its era and earned it a dedicated user base within hobbyist and educational communities. Its claim to fame included its highly compatible and upgradable design, reliable support for colour graphics and sound, and the ability to run the sophisticated OS-9 multitasking operating system, features which contributed to its unique place in home computing history.

• Manufacturer: Tandy Corporation (Radio Shack)
• Type: Home computer
• Released: 1983
• Cost at release: USD $199 (CAD ~$675 adjusted for inflation)
• Cost of a full deluxe system: USD $1,180 (CAD ~$4,000 adjusted for inflation)
• MIPS: 0.25 (250 KIPS)

Hardware Specifications

• CPU: Motorola 6809E, 8-bit, running at 0.89MHz
• RAM: Models with 16KB, 32KB, or 64KB RAM
• ROM: 8KB or 16KB (Color BASIC or Extended Color BASIC)
• Graphics:
  • Video Display Generator: MC6847
  • Resolution modes: up to 256×192 pixels (2 colors), 128×192 (2 or 4 colors), 128×96 (4 or 2 colors), text mode 32×16
  • 9 color palette
• Sound: 1 voice, 6-bit DAC
• Keyboard: 53-key, full-stroke QWERTY keyboard
• Storage: Cassette interface (1,500 baud); optional external floppy disk drive
• Expansion:
  • Cartridge/expansion port for ROM cartridges and hardware add-ons
  • Two analog joystick connectors
  • RS232 serial port
  • TV RF output

Operating System & Programming Languages 

• O/S:
  • Color BASIC: Built-in ROM operating system, an implementation of Microsoft BASIC, present on all Color Computer 2 units for essential system operation and BASIC programming.
  • Extended Color BASIC: An enhanced ROM version providing additional commands, especially for graphics and disk operations. Some models shipped with this, while others could be upgraded.
  • OS-9 Level 1: Optional disk-based multitasking, multi-user operating system by Microware; considered advanced for its time and enabled features like real multitasking with proper hardware (floppy drives, etc.).
  • NitrOS-9: A community-enhanced variant of OS-9 available later and retroactively compatible with the hardware

• Programming Languages:
  • Color BASIC / Extended Color BASIC: Interpretive BASIC supplied by default, making BASIC the primary language.
  • BASIC09: Structured BASIC compiler/interpreter used under OS-9 for more advanced software development.
  • 6809 Assembly Language: Machine code programs, often developed using assemblers and supported by direct ROM subroutines for I/O and graphics.
  • C: Available as a third-party compiler, particularly for OS-9.
  • Pascal: Pascal compilers were available from third parties, primarily targeting OS-9.
  • FORTH, LOGO, others: Various other language implementations were published on cartridge or disk by third-party vendors

Notables

• Affectionately called “CoCo” among enthusiasts and in hobbyist literature.
• Born from a Motorola and University of Kentucky project aiming to create an affordable agricultural videotex terminal for farmers—repurposed into a general home computer.
• Among the first affordable color home computers in North America.
• Early adopter of the Motorola 6809E, a highly advanced 8-bit CPU for its era.
• Supported multitasking with OS-9, quite rare in home computers at the time.
• “Melted” keyboard in early units was often criticized; later models received a better full-travel keyboard.
• Capable of displaying nine colors, but text mode was uppercase-only for most configurations, with lowercase support hidden in hardware for compatibility reasons.
• Highly stable hardware that rarely “crashed” compared to competitors.
• Sold directly in Radio Shack stores, making it highly accessible to families across North America

Donated by: Arlen Michaels