TRS Color Computers  Color Computer 2
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TRS80 Color Computer 2

The TRS 80 Color Computer 2, or popularly the CoCo 2, was introduced in 1983 as a replacement for the first CoCo, which was now known as the CoCo 1. The CoCo 2 has the same characteristics as the CoCo 1 but is equipped with a better keyboard and more integrated circuitry.

Several models of the CoCo 2 were produced, with increasing RAM capacities. The original version came with 8K RAM, but later the machine was provided with 16, 32 and finally 64K of RAM.

The CoCo 2 runs on the Motorola 6809E processor clocked at 0.89MHz. By programming the clock generator, speeds of 1.8MHz could be achieved.

Expansion Ports:

  • Expansion/Cartridge port
  • Two analog joystick connectors
  • Cassette Interface, 1500 baud
  • RS232 Serial port
  • RF TV connector

Motorola 6809 CPU

The Motorola 6809 is an 8-bit microprocessor with some 16-bit features. It was designed by Motorola's Terry Ritter and Joel Boney and introduced in 1978. Although source compatible with the earlier Motorola 6800, the 6809 offered significant improvements over it and 8-bit contemporaries like the MOS Technology 6502, including a hardware multiplication instruction, 16-bit arithmetic, system and user stack registers allowing re-entrant code, improved interrupts, position-independent code and an orthogonal instruction set architecture with a comprehensive set of addressing modes.

Motorola MC6847 Video Display Generator

The MC6847 is a video display generator (VDG) first introduced by Motorola and used in the following machines (this is not a full list):

  • TRS-80 Color Computer
  • Dragon 32/64
  • Laser 200
  • TRS-80 MC-10/Matra Alice
  • NEC PC-6000 series
  • Acorn Atom
  • APF Imagination Machine

The VDG is a relatively simple display generator compared to other display chips of the time. It is capable of displaying alphanumeric text, semigraphics and raster graphics contained within a roughly square display matrix 256 pixels wide by 192 lines high.

The ROM includes a 5 x 7 pixel font, compatible with 6-bit ASCII. Effects such as inverse video or colored text (green on dark green; orange on dark orange) are possible.

The MC6847 is capable of displaying nine colors:

  • black
  • green
  • yellow
  • blue
  • red
  • buff (almost-but-not-quite white)
  • cyan
  • magenta
  • and orange
Two extra colors, dark green and dark orange, are only possible as backgrounds for alphanumeric text modes.

Technical Details
Released 1983 Brand Tandy Radio Shack Type TRS Color Computers RadioShack Name Color Computer 2 CPU Class 6809 CPU Motorola MC6809 @0.89MHz Memory RAM: 16kB
RAM max: 64kB
Sound Chip none Sound 6 Bit D/A, or single bit sound. Display Chip MC6847 Video Display Generator Display Text & Bitmapped graphics with 9 colors
max 256x192 2 color mode
Best Color Bitmapped 9 color mode Best Graphics 256x192 in 2 colors Sprites none System OS BASIC or OS9 level 1 (with disk drive)
Related Systems
 
TRS Color Computers RadioShack
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Color Computer  2 (1983)
Related Media
 
Micro
The 6502/6809 Journal
World Wide Web Links
 
Wikipedia: Motorola 6809 CPU
Wikipage about the Motorola 6809 CPU and compatibles
 
WikiPedia: Motorola MC6847 Display Chip

The MC6847 is a Video Display Generator (VDG) first introduced by Motorola in 1978