The PONG and other micro video projects (from what i've read) set the bar at not requiring external support other than resistors to build the greyscale DAC. The '51 equiv can be found in a book by Mike Predko (? sp). While really neat projects, i wouldn't use one as the basis of a computer display, as is.

The pixel rate of all of these projects could be increased by using parallel to serial chips. Which is typical of most of the old TTY designs you'll find.

You'll find 2MHz Z80's were common in CRT and TTY display circuits with the hi-transaction rate stuff done in external hardware. Any one remember MICROANGELO (4MHz Z80).

Were i to generate video natively with an '51, i would want some resolution and want the ability to truly bit-map, so i would probably do something similar to what Steve Taylor mentions a few threads down.

I would go to my junk box to get some 32k Dual ports (1 if mono 3 for color) and use these as the frame store for a 640x350 line display. External counters would just continuously cycled thru the memory at a rate approp. for the display (probably a VGA monitor). The 8051 would just write to the one port patterns which would be the video and sync levels. IF external logic generated the sync levels then 640x400 mono could be achieved with 1 32k DP.

regards,
p