On Wed, Dec 4, 2024 at 5:58 PM Mike Katz <[email protected]> wrote: > > You are correct. The 6845 was monochrome and the 6847 was the color chip.
The 6845 was called the 'CRT Controller'. It was basically a set of programmable counters that would address the video RAM, generate sync signals, latch the address if a lightpen detected a 'hit' and so on. It did not do anything with the data from the video RAM, that was handled by other circuitry. It could certainly be used in colour systems, the BBC micro, IBM CGA card and so on. The 6847 was the the video display generator. It could generate the video addresses and timing (e.g. the Acorn Atom) but didn't have to. It did handle the data from the video RAM, it had an internal upper-case only character generator, block graphics, etc. It did generate colour video. -tony
