Improve PCM Quality Playback (In Sonic 1)
From Sonic Retro
According to the Overdrive II docs, the reason the Z80 is halted is to mitigate a hardware bug:
- "If the Z80 tries to access the bus while the VDP is doing a DMA from RAM/ROM or the 68k is halted because it tried to read from the VDP while its FIFO is empty or write to the VDP while its FIFO is full it has to wait for that to complete first.
- IIRC If the Z80 tries to access ROM while the VDP is doing a DMA from 68k RAM this can lead to corruption of RAM contents due to glitchy signals on the address bus (similar to the C64’s VSP bug)."