For the latest information about the system software for ATA devices such as the hard 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 specification for Ultra DMA IDE interface used in the iMac family of computers is ANSI T13/1153D and is available from the Technical Committee T13 web site at