from
The Free On-line Dictionary of Computing (8 July 2008)
SCSI-2
<hardware> A version of the {SCSI} command
specification.
SCSI-2 shares the original SCSI's {asynchronous} and
{synchronous} modes and adds a "{Fast SCSI}" mode (<10MB/s)
and "{Wide SCSI}" (16 bit, <20MB/s or rarely 32 bit).
Another major enhancement was the definition of command sets
for different device classes. SCSI-1 was rather minimalistic
in this respect which led to various incompatibilities
especially for devices other than {hard-disks}. SCSI-2
addresses that problem. allowing {scanners}, {hard disk
drives}, {CD-ROM} drives, tapes and many other devices to be
connected.
Normal SCSI-2 equipment (not wide or {differential}) can be
connected to a SCSI-1 bus and vice versa.
(1995-04-19)