AT Attachment Packet Interface (ATAPI) is the interface between connected CD-ROM and tape backup drives in your computer. To address hard disk drives, most personal computers today use the Integrated Drive Electronics (IDE) interface. ATAPI gives further commands needed to control a CD-ROM drive or tape backup. This allows the computer to utilize the IDE interface and its controllers to manage these devices.

ATAPI is a portion of the Enhanced IDE (EIDE) interface also known as ATA-2. This interface arose from a series of incremental developments. ATAPI was an evolution of the AT Attachment Interface, which in turn evolved from the IDE format. This evolution resulted to various interfaces with close similarity to ATAPI (terms and definitions below), including erroneously interchanged abbreviations. The original ATA was retroactively termed PATA with the introduction of Serial ATA in 2003.

Definition of Terms:

  • ATA or PATA – Parallel ATA is the original parallel ATA interface employed by disk drives.
  • ATAPI or PATAPI – ATAPI with PATA is the interface used by CD, DVD, or tape devices.
  • SATA – Serial ATA, a Parallel ATA serial version, is the interface utilized mostly by disk drives.
  • SATAPI – Serial ATAPI, ATAPI plus SATA, is another interface used by CD, DVD, or tape devices.

The PATA standards limit cable lengths up to 18 inches (46 centimeters) only. This length allowance makes the interface seem to be an internal computer storage. ATA has offered the least expensive and most widespread interface for this application. As of 2007, the more prevalent Serial ATA (SATA) has displaced it in newer systems.