The Symbiface 2 operates the IDE device in 16-bit data transfer mode. The 16-bit bits of data is buffered in at a time within the Symbiface 2 and read via the Data port below 8 bits at a time. The I/O ports operate in a "pass-through" like mode where the registers directly reflect those of the connected ATA device.
This is the documentation about the '''IDE registers''' of the [[SYMBiFACE II]] expansion card.