For information about the system software for ATA devices such as the IDE drive, see ATA Device Software for Macintosh Computers. That book is available on the reference library issue of the developer CD (June, 1999) and on the World Wide Web at
http://developer.apple.com/documentation/Hardware/DeviceManagers/ata/ata_ref/frameset.html
The implementation of the ATA interface on this computer is a subset of the ATA/ATAPI-4 specification (ANSI NCITS 317-1998 AT Attachment - 4 with Packet Interface Extension). That specification is maintained by the National Committee on Information Technology Standards (NCITS) Technical Committee T13; more information is available on their website at