PC Hardware in a Nutshell, 3rd Edition

IDE/ATA Standards and Implementations

Although IDE was originally proprietary, the cost and performance advantages of IDE quickly made it the standard hard disk interface. By 1990, most computer systems came with IDE hard disks. A slew of acronyms and standards has arisen as IDE proliferates, some meaningful and many that are just marketing hype. The formal ATA standards are maintained by Technical Committee T13 of the National Committee on Information Technology Standards (NCITS), and may be viewed at http://www.t13.org. These standards include:

ATA-1

The original IDE specification, ATA defines a standard 40-pin interface that supports two hard disk devices on one cable. ATA-1, adopted as T13 0791M and ANSI X3.221-1994, was withdrawn as a standard in 1999.

ATAPI (ATA Packet Interface)

The first ATA standard supported only hard disks. Manufacturers soon realized that the ubiquity, high performance, and low cost of the IDE interface also made it ideal for nondisk devices such as CD-ROM and tape drives. The ATAPI standard was developed to allow these nondisk devices to be connected to a standard ATA port. ATAPI hardware connects to and works with any standard IDE or EIDE port (explained later in this section). Note that, although ATAPI devices connect to ATA ports, they are not ATA devices, and differ significantly from an ATA hard drive. This is not a problem with most motherboard IDE ports and IDE interface cards, but caching controllers and other intelligent interfaces must be ...