About

About CoCoVGA

CoCoVGA is a hardware upgrade that produces VGA output from the TRS-80 Color Computer 2.

The current version snoops the digitial signals of the Motorola 6847 Video Display Generator (VDG) chip and imitates its functionality, producing a 640x480 60Hz VGA video output. CoCoVGA supports the standard text, semigraphics, and graphics modes (even those not supported by BASIC). It adds lowercase, multiple artifact modes, scanline emulation, and a customizable palette, in addition to other features.

To do this requires that the installer remove the 6847 from the system's main board and place the CoCoVGA board in the 6847 socket. Then the 6847 must be placed in the CoCoVGA board.

We are considering alternate board form factors to support more TRS-80 Color Computer 1 and 2 systems, as well as the MC-10 and Tano Dragon.

We have future plans to support the 6847T1, which was used on some later Color Computer 2 systems.

Project Contributors

Hardware

  • Early inspiration (video chip replacement on TI-99/4a: the F18A project - here and here to produce VGA output) and guidance on FPGA to TTL level shifting: Matthew Hagarty
  • 6847 reverse-engineering: Brendan Donahe and Steve Spiller
  • Initial hardware prototyping: Brendan Donahe and Steve Spiller
  • FPGA design: Brendan Donahe
  • Prototype board design: Ed Snider
  • Production board designs: Ed Snider
  • Board and cable assembly: Ed Snider

Software

  • Blanking region combo-lock concept and 6809 assembly language routine: Brendan Donahe and Steve Spiller
  • Demos, tests, and utilities: Brendan Donahe and Steve Spiller
  • Infocom game ports to use 64-column mode: Ed Snider

Web Site

  • CoCoVGA logos and color scheme: Robin Donahe
  • Content management software: ProcessWire atop Apache, MySQL, and PHP
  • Color Computer true-type fonts: Rebecca G. Bettencourt

Special Thanks...

  • to Simon Jonassen for:
    • pointing out the ability of the 6847 to display 11 simultaneous colors on the text/SG4 display
    • numerous challenging demos to run against CoCoVGA
  • to Ed Snider for:
    • application of rock-star hardware skills to board design and production
    • application and game software to take advantage of enhanced modes including VG6 (16-color 128x96) and W64 (64-column text mode)
    • general guidance, tips, and intelligent questions
  • to Boisy Pitre for:
    • application of his amazing NitrOS-9 knowledge and awesome programming skills to enable 64-column text mode in NitrOS-9 Level 1
  • to David Linsley for:
    • his donation of a PAL Dragon 32 to confirm and, in the future, ensure CoCoVGA compatibility