Adaptec 1742A, 1744 Host Adapter, IBM PC-AT Compatible, Industry Standard Architecture, Initiator

EISA-to-Fast SCSI Host Adapter Glossary

Host Adapter

A hardware printed circuit board that installs in a standard microcomputer backplane and provides a SCSI bus connection so that SCSI devices can be connected to the microcomputer. A host adapter is intelligent if it has a simple high-level software inter- face to the microcomputer. A host adapter is dumb if the micro- computer must directly manage the SCSI protocol using the microcomputer processor.

IBM PC-AT Compatible

Any computer system that emulates exactly the IBM PC-AT and that uses an ISA backplane bus.

Industry Standard Architecture

The IBM PC-AT functions have been duplicated by a number of manufacturers. All the IBM PC-AT compatible machines use a backplane bus that very closely emulates the function of the back- plane bus of the PC-AT. Because of the broad usage of this bus structure, it has become known as the Industry Standard Archi- tecture bus, even though there is no presently accepted standard for the bus.

Initiator

A SCSI device that requests an operation to be performed by another SCSI device (the target). The initiator provides all the command information and parameters required to perform the operation, but the details of the operation are actually sequenced by the target.

ISA

See Industry Standard Architecture

Logical Unit

A physical or virtual device addressed through a target.

Logical Unit Number

An encoded three-bit identifier for a logical unit.

LU

See Logical Unit

LUN

See Logical Unit Number

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