TERMINATION
A physical requirement of the SCSI bus. The first and last devices on the SCSI bus must have terminating resistors installed, and the devices in the middle of the bus must have terminating resistors removed. The Single Ended electrical class depends on very tight termination tolerances, but the passive 132 ohm termination defined in 1986 is mismatched with the cable impedance (typically below 100 ohms). Although not a problem at low speeds when only a few devices are connected, reflections can cause errors when transfer rates increase and/or more devices are added. In
U
UltraSCSI
A method that enables very fast data transfer rate on the SCSI bus. The maximum UltraSCSI data transfer rates are 20 MBytes/ second (40 MBytes/second for Wide SCSI host adapters).
V
W
Wide SCSI
Provides for performance and compatibility enhancements to
Appendix C Glossary of Terms 53
