SCSI Standards
Here is a brief overview of the various SCSI standards: SCSI (SCSI-1) This standard is obsolete. It supported up to 16 devices
on a single SCSI chain and required each chain (internal and external) to
be terminated.
SCSI-2 This is also called Fast SCSI. SCSI-2 improved the speed of the original
standard to 20MBps. It allowed for either active or passive termination and used
a high-voltage differential (HVD) bus.Chapter 19: Ports and Connectors^505
Figure 19-18. External SCSI connectors