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

Commands

| Command | Code | | ------------ | ------ | | Recalibrate | 10h | | Read Sector | 20h | | Write Sector | 30h | | Seek | 70h |

Command Sequence

1. Wait BSY=0, RDY=1
2. Write parameters (322h-326h)
3. Write command (327h)
4. Wait for IRQ or poll DRQ
5. Transfer data
6. Read status

References

See references/ for detailed documentation.