Tandy Color Computer 16K

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