ATA Packet Interface (ATAPI) is a protocol that has been added to

Parallel ATA Parallel ATA (PATA), originally , also known as IDE, is a standard interface designed for IBM PC-compatible computers. It was first developed by Western Digital and Compaq in 1986 for compatible hard drives and CD or DVD drives. The connection ...

and

Serial ATA SATA (Serial AT Attachment) is a computer bus interface that connects host bus adapters to mass storage devices such as hard disk drives, optical drives, and solid-state drives. Serial ATA succeeded the earlier Parallel ATA (PATA) standard t ...

so that a greater variety of devices can be connected to a computer than with the ATA command set alone. It carries

SCSI Small Computer System Interface (SCSI, ) is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, electrical, optical and logical interface ...

commands and responses through the ATA interface. ATAPI devices include CD-ROM and DVD-ROM drives, tape drives, magneto-optical drives, and large-capacity floppy drives such as the Zip drive and SuperDisk drive.

Background

ATA was originally designed for, and worked only with hard disks and devices that could emulate them. A group called the Small Form Factor committee (SFF) introduced ATAPI (ATA Packet Interface) ATA to be used for a variety of other devices that require functions beyond those necessary for hard disks. For example, any removable media device needs a "media eject" command, and a way for the host to determine whether the media is present, and these were not provided in the ATA protocol. The Small Form Factor committee approached this problem by defining ATAPI, the "ATA Packet Interface," as part of the fourth generation of ATA. ATAPI carries SCSI commands through ATA, so ATAPI devices are "speaking SCSI" other than at the electrical interface. In fact, some early ATAPI devices were simply SCSI devices with an ATA/ATAPI to SCSI protocol converter added on. The SCSI commands and responses are embedded in "packets" (hence "ATA Packet Interface") for transmission on the ATA cable. This interfaces ATA with any device class for which a SCSI command set has been defined. ATAPI devices are also "speaking ATA" because the ATA physical interface and protocol are still being used to send the packets. The Direct Memory Access feature for the ATA interface was introduced along with ATAPI.

Definition

The SCSI commands and responses used by each class of ATAPI device (CD-ROM, tape, etc.) are described in other documents or specifications specific to those device classes and are not within ATA/ATAPI or the T13 committee's purview. One commonly used set is defined in the

MMC MMC may stand for: Business *Mail.com Media Corp., a former name of the US digital media company PMC * Marsh & McLennan Companies, an American-based global professional services firm *Master Municipal Clerk, a certification in the US for a munic ...

SCSI command set. ATAPI was adopted as part of ATA in INCITS 317-1998, ''AT Attachment with Packet Interface Extension (ATA/ATAPI-4)''.

References

External links

* {{cite web , last1=Necasek , first1=Michal , title=The Secret History of ATAPI , url=https://www.os2museum.com/wp/the-secret-history-of-atapi/ , website=OS/2 Museum , access-date=25 November 2021 , date=24 November 2021 Communications protocols AT Attachment SCSI

Background

Definition

See also

References

External links