Compaq Deskpro 2000 Maintenance & Service Manual page 231

Termination
1. Every SCSI chain must be terminated at both ends regardless of whether it is an internal SCSI
chain, an external SCSI chain, or a combination internal-external SCSI chain.
2. The PD-CD drive must be terminated by using a SCSI interconnect cable that has a terminating
plug on one of its ends. This drive does not ship with terminating resistors.
3. Compaq SCSI-2 controllers have an automatic terminating device which turns OFF the terminator
when both the external and internal SCSI signal ports connect to SCSI devices.
4. A terminating resistor plug is molded into one end of some internal flat SCSI signal cables. It
may also be a separate electronic device that installs into the SCSI signal port of an external
device, installs into an internal flat SCSI signal cable connector, or installs into the SCSI signal
port of some non-Compaq SCSI-2 controllers.
5. Terminators are generally designated as being active or passive by the voltage limiting method
used. Both types of terminators come in the forms described in 2, 3, and 4 above. The product
documentation usually describes the terminator type.
6. All Compaq SCSI-2 controllers have active terminators. Active terminators more effectively filter
out electronic noise (voltage surges) on the SCSI chain than passive terminators.
7. To ensure the integrity of data transferred faster than 5 megabytes per second, use active
terminators to terminate the SCSI chain.
D-2 SCSI Guidelines