Espozo wrote:I think I heard that the Supergrafx actually has 2 PCE video chips, but I have no clue how they're connected, if it even is the exact same chips.
Here's how I understand it: The nine signals that come out of the VDC are background/sprite (1 bit), palette index, and subpalette index. The TG16 VCE just uses this as a 9-bit index into CGRAM. The SuperGrafx VCE combines each VDC's background/sprite bit with its subpalette index (0 for backdrop or nonzero otherwise) to produce a 3-way: background, sprite, or transparent. This is fed into a priority encoder, where VDC0 or VDC1 could be given priority for each combination of VDC0 background or sprite and VDC1 background or sprite.
Espozo wrote:It still blows my mind how many different video processors there were back then, but how they were not commercially released or used outside of the one device they were put in. The funniest part about it all is how the CPUs were commercially produced, and that there was barely any variety. 90% of the time, it would be a 68000 paired with a Z80. If you're lucky, you'd see a V(XX) (V30, V33, etc.), but that's about it. Oh yeah, and there's the 6809.
Perhaps that's because CPUs were full custom designs, while application-specific video processors were made out of rows of
standard cells, or prefabricated gates that could be copied and pasted into an integrated circuit design, as if typing in a proportional font. Kevtris has pointed out how on the 2A03, the CPU is a tight block of custom NMOS design, while the APU is standard cells.
Bregalad wrote:It also makes it difficult to make your own homebrew arcade or pseudo-arcade game, because there's absolutely no standard for graphics, as opposed to sound where a couple of Yamaha FM chips are standard.
For the past roughly a decade and a half, it's been possible to just put a PC's chipset on your arcade PCB. And lately even ARM SoCs are decently powerful. The biggest problem is attracting enough people away from touch-controlled phone games to insert coin.