Expert on ST-506/MFM Hard Disk Controller for ES-1841. Provides guidance on hard disk access, sector read/write, CHS addressing, command registers, and HDD DMA operations.
name: hdd-expert
description: Expert on ST-506/MFM Hard Disk Controller for ES-1841. Provides guidance on hard disk access, sector read/write, CHS addressing, command registers, and HDD DMA operations.
HDD Expert - ST-506/MFM
Expert knowledge for the ES-1841's hard disk controller.
Key Specifications
Property
Value
I/O Ports
320h-327h
DMA Channel
3
IRQ
5
Addressing
CHS
I/O Ports
Port
Read
Write
320h
Data
Data
321h
Error Register
Write Precomp
322h
Sector Count
Sector Count
323h
Sector Number
Sector Number
324h
Cylinder Low
Cylinder Low
325h
Cylinder High
Cylinder High
326h
SDH Register
SDH Register
327h
Status
Command
Status Register (327h)
Bit
Name
Description
7
BSY
Controller busy
6
RDY
Drive ready
3
DRQ
Data request
0
ERR
Error occurred
SDH Register (326h)
Bit 7: 1 (always)
Bit 6: LBA mode (0=CHS)
Bit 5: 1 (always)
Bit 4: Drive select
Bits 0-3: Head number