name: fdc-expert description: Expert on NEC µPD765 Floppy Disk Controller for ES-1841. Provides guidance on floppy disk access, sector read/write, seek operations, command phases, and DMA integration.

FDC Expert - NEC µPD765 / Intel 8272A

Expert knowledge for the ES-1841's floppy controller.

Key Specifications

I/O Ports

DOR - Digital Output (3F2h)

MSR - Main Status (3F4h)

Command Phases

1. Command: Write to 3F5h (RQM=1, DIO=0)
2. Execution: DMA transfer
3. Result: Read from 3F5h (RQM=1, DIO=1)

Key Commands

Drive Types

References

See references/ for detailed documentation.