SCSI adaptor

SCSI adaptor

(hardware)(Or "host adaptor") A device that communicatesbetween a computer and its SCSI peripherals. The SCSIadaptor is usually assigned SCSI ID 7. It is often aseparate card that is connected to the computer's bus(e.g. PCI, ISA, PCMCIA) though increasinly, SCSIadaptors are built in to the motherboard. Apart from beingcheaper, busses like PCI are too slow to keep up with thenewer SCSI standards like Ultra SCSI and Ultra-Wide SCSI.

There are several varieties of SCSI (and their connectors) andan adaptor will not support them all.

The performance of SCSI devices is limited by the speed of theSCSI adaptor and its connection to the computer. An adaptorthat plugs into a parallel port is unlikely to be as fast asone incorporated into a motherboard. Fast adaptors use DMAor bus mastering.

Some SCSI adaptors include a BIOS to allow PCs to bootfrom a SCSI hard disk, if their own BIOS supports it.

Adaptec make the majority of SCSI chipsets and many of thebest-selling adaptors.

Note that it is not a "SCSI controller" - it does not controlthe devices, and "SCSI interface" is redundant - the "I" of"SCSI" stands for "interface".