Chapter 6. The ATAIDE Interface

Chapter 6. The ATA/IDE Interface

The interface used to connect hard disk and optical drives to a modern PC is typically called IDE (Integrated Drive Electronics); however, the true name of this interface is ATA (AT Attachment). The ATA designation refers to the fact that this interface was originally designed to connect a combined drive and controller directly to the 16-bit bus found in the 1984 vintage IBM AT (Advanced Technology) and compatible computers. The AT bus is otherwise known as the ISA (Industry Standard Architecture) bus. Although ATA is the official name of the interface, IDE is a marketing term originated by some of the drive manufacturers to describe the drive/controller combination used in drives with the ATA interface. IDE refers to the fact that the interface electronics or controller is built in to the drive and is not a separate board, as with earlier drive interfaces. Although the correct name for the particular IDE interface we most commonly use is technically ATA, many persist in using the IDE designation today. If you are being picky, you could say that IDE refers generically to any drive interface in which the controller is built in to the drive, whereas ATA refers to the specific implementation of IDE that is used in most PCs.

ATA is used to connect not only hard disks, but also optical (CD-ROM and DVD-ROM) drives, high-capacity SuperDisk or Zip drives, and tape drives. Even so, ATA is still thought of primarily as a hard disk interface, and it evolved directly from the separate controller and hard drive interfaces that were used prior to ATA. This chapter covers the standard parallel version of ATA as well as the newer Serial ATA (SATA) interfaces; it also briefly mentions the original interfaces from which ATA evolved.

Although virtually every server contains one or more ATA interfaces, the parallel ATA (PATA) interface is used primarily for CD-ROM and DVD-ROM optical drives on midrange and high-end servers. These servers typically use the SCSI interface for hard disks. However, the newer SATA interface is being used by all levels of servers for hard disk interfacing.