Tandy Color Computer 16K

[Vin98]

The Tandy Color Computer 16K, popularly known as the “CoCo,” was a notable early 1980s home computer recognized for its use of the powerful Motorola 6809E CPU and its ability to display color graphics when connected to a standard television. It stood out for its affordability, flexible cartridge-based expansion, and the inclusion of Microsoft’s Color BASIC in ROM, making it accessible for both gaming and educational programming applications.

  • Manufacturer: Tandy Corporation (Radio Shack)
  • Type: Home computer
  • Released: 1980
  • Cost at release: USD $599 (CAD ~$2,575 adjusted for inflation)
  • MIPS: 0.35 (350 KIPS)

Hardware Specifications

  • CPU: Motorola 6809E, 8-bit, running at 0.895MHz
  • Memory: 16KB RAM (expandable internally up to 32KB or 64KB on later models)
  • ROM: 8KB Microsoft Color BASIC, with optional 8KB Extended Color BASIC
  • Keyboard: 53-key “chiclet” keyboard (QWERTY layout with function and arrow keys)
  • Video Output: RF modulated for standard TV; resolutions up to 256×192 pixels; 8 colors maximum
  • Sound: 6-bit digital-to-analog converter for one-voice sound
  • Graphics Modes: 32×16 text, and multiple low/high-res graphics modes, with color and semigraphics capability
  • I/O Ports:
    • Cassette tape interface (1500 baud)
    • Two analog joystick ports
    • Cartridge slot for software/program expansion
    • RS-232 serial interface (modem/printer connection)
    • Operating System: Microsoft Color BASIC (with optional Extended BASIC); supported OS-9 from third parties
  • Weight: Approximately 4.75lbs (2.15kg)

Operating System & Programming Languages 

  • O/S:
    • Standard ROM-based OS:
      • All models of the Tandy Color Computer ran Microsoft Color BASIC (provided in ROM), which boots directly at power-up.
      • Many units were also upgraded with Extended Color BASIC, offering enhanced graphics and program features.
    • Optional Disk and Advanced Operating Systems:
      • Disk Extended Color BASIC (DECB): Added disk support for floppy drives.
      • OS-9: A multitasking, multiuser operating system sold by third parties, notable for its Unix-like features and support for more advanced programming environments. Required upgraded RAM (typically 64K or more).
      • Other operating systems such as FLEX were also ported to the system by the community

  • Programming Languages:
  • BASIC:
    • Microsoft Color BASIC (in ROM)
    • Extended Color BASIC (in ROM, larger models)
    • Disk Extended Color BASIC (with floppy disk support)
  • Assembly Language:
    • Motorola 6809 assembly language
    • Programs could be created using tools like EDTASM+ (Editor/Assembler/Debugger) cartridges and various machine language monitors
  • Other High-Level Languages (usually via cartridge or disk):
    • BASIC09: Advanced structured BASIC, included with the OS-9 operating system
    • Pascal: Available from third parties for OS-9
    • C: Available for OS-9
    • FORTH: Community and commercial cartridges
    • COBOL, LOGO: Less common, but available through user groups or third-party vendors
  • Machine Code/Hex:
    • Directly loaded or assembled machine code programs

Notables

  • Firsts: Among the earliest affordable home computers with true color graphics and sound, supporting up to eight colors while connected to a regular TV.
  • Advanced CPU: Featured the Motorola 6809E, one of the most sophisticated 8-bit CPUs of its era, offering advanced addressing and instruction capabilities for home use.
  • Cartridge Slot: Popularized “Program Pak” ROM cartridges, making commercial games and educational software easy to load and run.
  • Multitasking OS: Supported OS-9 a Unix-like, multitasking operating system, which was rare for home computers at the time.
  • A competitor of the Commodore VIC-20 and Atari 400/800 in the consumer market.
  • Unique “chiclet” keyboard and silvery, futuristic styling made it stand out in the showroom.
  • Although labeled a TRS-80, it was completely incompatible with other TRS-80 computers, an early source of consumer confusion.
  • Longevity: Its architecture was so flexible that the line survived for more than a decade and inspired a strong software ecosystem.

Donated by: Arlen Michaels

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