Interesting ! ROMs are basically a programmable logic devices, the only difference is that they're purely combinational and have only fixed input and output pins (they can't be bidirectional and outputs have a common enable signal). So basically it'd be the same as doing it with PAL chips except it's even more limited.
Quote:
Somebody should make an arcade game out of EPROMs
Since it's the bottleneck of available chips on the market, you should start by making a valable "PPU" with only EPROMs (and maybe a DAC for the composite video signal !), and that'd already be impressive. If a "real" CPU and sound chips are still needed it's still impressive.