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(Advanced SCSI Programming Interface) An interface specification developed by Adaptec, Inc., Milpitas, CA, that provides a common language between drivers and SCSI host adapters. Drivers written to the ASPI interface can access peripherals that reside on different versions of SCSI host adapter hardware. See SCSI.

The ASPI Interface
The ASPI Manager is the software that supports the ASPI interface. ASPI drivers call ASPI functions to access SCSI peripherals. The ASPI Manager for the SCSI host adapter processes these function calls and generates the appropriate SCSI commands to the SCSI peripherals.


(Small Computer System Interface) Pronounced "scuzzy," SCSI is a hardware interface for up to 15 peripherals connected to one PCI or PCI Express card ("SCSI host adapter") on the motherboard. Introduced in 1986 by Shugart Associates (see SASI), this original parallel architecture was largely replaced by a serial version (see serial attached SCSI).

SCSI hard drives were used in mainframes, servers and storage arrays in the late-1980s and 1990s because they were very robust, and they were initially the only ones used in RAID configurations (see RAID). Eventually, less-costly IDE drives became highly reliable (see IDE and SATA).

SCSI Is a Mini-LAN
The SCSI bus is like a mini-LAN connecting 15 devices; actually 16 but the host counts as one. Any two can communicate at one time: host-to-peripheral and peripheral-to-peripheral. For more details, see SCSI Architecture Model, SCSI signaling, SCSI connectors and SCSI switch.

A "Scuzzy" Daisy Chain
SCSI enabled multiple peripherals to connect to one host adapter and take up only one slot in the computer. Devices included two ports to form a daisy chain.

SCSI Ports
SCSI devices have in and out ports as well as a dial to set the number of the device. These parallel port sockets are on the back of a 1990s vintage disk drive.

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