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I find it interesting that the Sega Genesis (Mega Drive) also was backwards compatible with the Sega Master System. Inside the Genesis they had the hardware fo

by djmips 2y ago

I find it interesting that the Sega Genesis (Mega Drive) also was backwards compatible with the Sega Master System. Inside the Genesis they had the hardware for the Master System, which included the original Z80, the original sound chip. The Genesis graphics chip was evolved from the Master System and could work in Master System mode. You needed a cartridge adapater. The other surprising thing is that you could actually run the Z80 in parallel with your 68000 when running a Genesis game. We used the Z80 as a sound co-processor running MIDI and playing sampled drums without bothering the 68000. On the PS2 system's PS1 backwards compatibility this pattern is quite similar, not mentioned in the blog posts is that the IOP which acts as the PS2's sound co-processor contains an R3000 like the PS1 and it's underclocked to directly run the PS1 titles. Apparently on later editions of the PS2 Slim they removed the R3000 based IOP and replaced it with a PowerPC microcontroller! It had to fully emulate the R3000 and the SPU as far as I know to fufill the IOP duties including the PS1 emulation.

memorydial 2y ago
[flagged]
poke646 2y ago
> The other surprising thing is that you could actually run the Z80 in parallel with your 68000 when running a Genesis game. We used the Z80 as a sound co-processor running MIDI and playing sampled drums without bothering the 68000. I always thought that was a key reason to include a Z80. A dedicated sound processor (often Z80) was a mainstay of arcade games from the mid-80s and onward and SEGA's engineers would surely have been familiar with such a design. It might even have helped when porting arcade games.
- skywal_l 2y ago
  They were because sega was, at the time, an arcade manufacturer first. The Megadrive is the console version of the system 16 after all.
MonaroVXR 2y ago
Do you happen to have a source of this? (Copetti?)

by djmips 2y ago

memorydial 2y ago

[flagged]

poke646 2y ago

> The other surprising thing is that you could actually run the Z80 in parallel with your 68000 when running a Genesis game. We used the Z80 as a sound co-processor running MIDI and playing sampled drums without bothering the 68000. I always thought that was a key reason to include a Z80. A dedicated sound processor (often Z80) was a mainstay of arcade games from the mid-80s and onward and SEGA's engineers would surely have been familiar with such a design. It might even have helped when porting arcade games.

skywal_l 2y ago
They were because sega was, at the time, an arcade manufacturer first. The Megadrive is the console version of the system 16 after all.

MonaroVXR 2y ago

Do you happen to have a source of this? (Copetti?)