3 ms·
Yeah, Mode 5 is pretty different from any of the TMS9918A modes and it lacks those older modes (unlike the SMS VDP), but there are a number of funny details tha
by mikepavone 4y ago
Yeah, Mode 5 is pretty different from any of the TMS9918A modes and it lacks those older modes (unlike the SMS VDP), but there are a number of funny details that only really make sense if you understand its predecessors. The bits in the command word are arranged strangely and the two registers that control the starting address for the background planes are laid out differently from each other.
- djmips 4y agoAccolade used the TI documentation as part of their clean room reverse engineering of the Mega Drive.
- mikepavone 4y agoOh really, I hadn't heard that before. From doing some searching I see that elsewhere you mention that you worked at Accolade. Would be curious to hear more of the story of how that reverse engineering went down. I wouldn't think the TI manual would be all that useful given how much changed between the TMS9918A and the Mega Drive VDP. I guess knowing what a register write looks like is a lot better than starting from zero though.