No µLaw here. The PCM feature of the YM2612 was just a raw 8-bit wide register that replaced the value of the FM accumulator for channel 6. So the YM2612 wasn't doing anything to your sound. It's just 8-bit, and that's audible. Frequency was often arbitrarily fixed (depending on the game needs and available ROM space). However, to update the DAC value of the PCM feature, coders had to manage the timing in software. No hardware facility (like interrupts or DMA) for this. Eventually, as the Sega Genesis had two microprocessors (68000 and Z80), the Z80 was very often programmed to manage the YM2612 (thus PCM playback).Boombastix wrote: ↑31 Jul 2019Can you please clarify if the PCM channel has uLaw compression (or similar bit compression) or not? And if you are able to pitch shift the sound in between uLaw coding and uLaw de-coding? (i.e. like real old hw, but streaming in this case).
If my question is heading in the wrong direction, then help me out by explaining if/how the PCM channel can do that Linn/Mirage (Sega too I guess), pitch shifted, bit compressed, sound. Thanks!
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