Adaptec 1744, AHA-1740A Common Command Set, Configuration, Control Microprocessor, Device Driver

Models: AHA-1740A 1742A 1744

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Common Command Set

EISA-to-Fast SCSI Host Adapter

Glossary

Common Command Set

A de facto standard SCSI command set for communication with fixed disk drives. The Common Command Set (CCS) is the basis for the SCSI-2 command set for all types of peripheral devices.

Configuration

The operation of configuring a device on the EISA bus through access of registers in the device by the host. It replaces the method of using jumpers common on ISA bus devices.

Control Microprocessor

An integrated circuit computer used to execute the software that controls the host adapter’s operation.

Device Driver

A program that is linked with, or attached to, an operating sys- tem to map the software interface of the operating system to the requirements of attached peripheral devices and host adapters. Under ASPI, the main component associated with the board is known as a Manager.

DMA

See Direct Memory Access

Differential

A term referring to the electrical characteristics of the signals used on the SCSI bus interface. Differential signals occupy two conductors with a positive (+) and negative (-) polarity component of the signal. This minimizes the effect of common mode signal noise and allows the SCSI bus to operate reliably over greater dis- tances at a higher speed.

Direct Memory Access

A mechanism that allows hardware control of the transfer of streams of data to or from the main memory of a computing sys- tem. The mechanism may require setup by the host software. After initialization, it automatically sequences the required data transfer and provides the necessary address information.

Disconnect/Reconnect

Disconnect is the function that occurs when a target releases con- trol of the SCSI bus, allowing the bus to go to the Bus Free phase.

GL-3

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Adaptec 1744 Common Command Set, Configuration, Control Microprocessor, Device Driver, Differential, Direct Memory Access