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The MC6847 is a video display generator (VDG) first introduced by Motorola and used in the TRS-80 Color Computer, Dragon 32/64, Laser 200, TRS-80 MC-10, NEC PC-6000 series, Acorn Atom, and the APF Imagination Machine, among others. It is a relatively simple display generator compared to other display chips of the time. It is capable of displaying text and graphics contained within a roughly square display matrix 256 pixels wide by 192 lines high. It is capable of displaying nine colors: black, green, yellow, blue, red, buff (almost-but-not-quite white), cyan, magenta, and orange. The low display resolution is a necessity of using television sets as display monitors. Making the display wider risked cutting off characters due to overscan. Compressing more dots into the display window would easily exceed the resolution of the television and be useless.[2][3]
Video modes
| Video Mode | Resolution | Colours | Bytes |
|---|---|---|---|
| Alphanumeric Internal | 32 × 16 | 2 | 512 |
| Alphanumeric External | 32 × 16 | 2 | 512 |
| Semigraphics 4 | 64 × 32 | 8 | 512 |
| Semigraphics 6 | 64 × 48 | 4 | 512 |
| Color Graphics 1 | 64 × 64 | 4 | 1024 |
| Resolution Graphics 1 | 128 × 64 | 1 + Black | 1024 |
| Color Graphics 2 | 128 × 64 | 4 | 2048 |
| Resolution Graphics 2 | 128 × 96 | 1 + Black | 1536 |
| Color Graphics 3 | 128 × 96 | 4 | 3072 |
| Resolution Graphics 3 | 128 × 192 | 1 + Black | 3072 |
| Color Graphics 6 | 128 × 192 | 4 | 6144 |
| Resolution Graphics 6 | 256 × 192 | 1 + Black | 6144 |
See also
- Motorola 6845, video address generator
- List of home computers by video hardware
References
- ^ Chip datasheet in PDF
- ^ Benchoff, Brian (29 January 2016). "VGA In Memoriam". Hackaday.
- ^ Posey, Bruce Charles (1982). Graphics Using the Motorola 6847 Integrated Circuit. W.S.U. Printing Service.