Virtual mode interrupt support:
- Gate array needs physical M1 bus cycles (fetchPhysicalMem in fetchOpcode)
for internal clocks (8253 timer, interrupt controller) to advance
- MZ2500 driver overrides cpu->_Z80.reti and cpu->_Z80.fetch with custom
handlers (MZ2500_retiHandler, MZ2500_fetchByte) — zero core changes
- Physical RETI bus sequence (ED 4D plant + M1 fetch) clears IC in_service
- One-shot INT suppression prevents premature interrupts during I=0x02 init
- Physical RETI cleanup at suppression boundary clears accumulated in_service
D88 native format handler (WD1773.c):
- Sparse/contiguous auto-detection for track mapping strategy
- Physical (C,H) → D88 index mapping built from sector headers (Balloon Fight)
- Index-based identity mapping for standard/H-swapped disks (Galaga, CP/M)
- d88PhysMap array with proper allocation/cleanup
Driver architecture cleanup:
- All MZ-2500 interrupt logic in MZ2500.c driver (not Z80CPU.c core)
- Custom RETI/fetchByte set directly on cpu->_Z80 function pointers
- Core Z80CPU.c unchanged from pre-MZ-2500 state for other machines
- Debug shell: psync command, intcount with /INT pin diagnostic
- MZ8BFI: MAX_DISK_DRIVES reduced to 2 for PSRAM heap
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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