host adaptor

SCSI adaptor
host adaptor
SCSI controller
SCSI interface

   <hardware> (Or "host adaptor") A device that communicates
   between a computer and its {SCSI} {peripherals}.  The SCSI
   adaptor is usually assigned {SCSI ID} 7.  It is often a
   separate card that is connected to the computer's {bus}
   (e.g. {PCI}, {ISA}, {PCMCIA}) though increasinly, SCSI
   adaptors are built in to the {motherboard}.  Apart from being
   cheaper, busses like PCI are too slow to keep up with the
   newer SCSI standards like {Ultra SCSI} and {Ultra-Wide SCSI}.

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

   The performance of SCSI devices is limited by the speed of the
   SCSI adaptor and its connection to the computer.  An adaptor
   that plugs into a parallel port is unlikely to be as fast as
   one incorporated into a motherboard.  Fast adaptors use {DMA}
   or {bus mastering}.

   Some SCSI adaptors include a {BIOS} to allow PCs to {boot}
   from a SCSI hard disk, if their own BIOS supports it.

   {Adaptec} make the majority of SCSI {chipsets} and many of the
   best-selling adaptors.

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

   (1999-11-24)