SYMBiFACE II:IDE registers
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The Symbiface 2 operates the ATA/IDE device in 16-bit data transfer mode. 16-bits of data is buffered at a time within the Symbiface 2 and read/written via the Data port I/O address 8 bits at a time. The device was designed when devices didn't support ATA CFA command set and 8-bit PIO data transfer so this is why it buffers 16-bit of data. (16-bits is the "native" data transfer of an ATA device).
The I/O ports operate in a "pass-through" like mode where the registers directly reflect those of the connected ATA device.
The X-Mass is a more modern ATA/IDE device which is compatible with the Symbiface 2 IDE registers and uses the same I/O ports.
This is the documentation about the IDE registers of the SYMBiFACE II expansion card.
| Port | Read | Write |
| #FD06 | Alternate Status | Digital Output |
| #FD07 | Drive Address | (Not Used) |
| #FD08 | Data Register | Data Register |
| #FD09 | Error Register | Features Register/(Write Precomp Reg.) |
| #FD0A | Sector Count | Sector Count |
| #FD0B | Sector Number (LBA bits 0-7) | Sector Number (LBA bits 0-7) |
| #FD0C | Cylinder Low (LBA bits 8-15) | Cylinder Low (LBA bits 8-15) |
| #FD0D | Cylinder High (LBA bits 16-23) | Cylinder High (LBA bits 16-23) |
| #FD0E | Device/Head Register (LBA bits 24-27) | Device/Head Register (LBA bits 24-27) |
| #FD0F | Status Register | Command Register |
