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#sega-genesis

2 posts

RetrogamingDeep Dive October 4, 2026 7 min read

Sega Genesis YM2612 Channel 3 Special Mode: Four Frequencies, One FM Channel

Decode YM2612 register 27h special mode, map channel 3 operator frequencies, preserve timer controls, and test key-on and frequency-latch behavior.

#sega-genesis#megadrive#ym2612

RetrogamingDeep Dive October 4, 2026 7 min read

Mega Drive Z80 Bus Handoff: BUSREQ, Reset, and Shared Sound RAM

Coordinate 68000 access to Mega Drive Z80 memory with BUSREQ polling, reset separation, byte-lane care, safe release, and reproducible audio-subsystem diagnostics.

#sega-genesis#z80#bus-arbitration