For most applications, the typical 805x is 100-1000x as fast as necessary in order to manage its tasks. For a CRT, however, it's very important that the timing generator, in this case, the 805x, produce horizontal sync, vertical sync, horizontal blanking, vertical blanking, with the required precise timing relationships that, in this case, VGA timing requires. It's also necessary that R, G, and B be produced, at analog levels, at a suitable rate. R, G, and B have to be produced at something on the order of ~28 MHz. That would be a challenge, particularly if one doesn't simply drive a DAC and use a fixed image table-lookup to produce R, G, and B.

I'd say that's a challenge, not an impossible one, perhaps, but a challenge nevertheless, even for the fastest of 805x's.

RE