Continuing the discussion from Yet another TMS9900 computer:
As I mentioned in @bdk6’s thread, Quinn Dunki has made a number of comments on 8-bit machine video production in her series on her Veronica 6502-based homebrew computer. The original Veronica used an Atmel microcontroller as a “GPU” (with additional updates after that article) to tackle this problem. In recent months she’s been updating it to use a TMS9918A replacement, the F18A, which is currently not in production.
What I failed to appreciate is that any given 1980s computer was not a CPU and some RAM hanging off a bus. It was a crazy mad scientist method of generating video based on the fever dream of a hardware engineer who had spent a little too much time watching The Last Starfighter, and maybe not quite enough time reading reference circuits for the parts in her drawers. Every 1980s computer was an experiment in a new way to generate graphics, and everything else (CPU, RAM, etc) was an accessory to that effort. This is crucial to understand, and it’s something that nobody in the home-brew computer world ever seems to talk about.
(Emphasis in the original.)