Installing the A5150A Adapter
SCSI Bus Termination
SCSI Bus Termination
The devices that make up the SCSI bus are connected serially (chained together) with SCSI cables. The first and last physical SCSI devices connected on the ends of the SCSI bus must have a set of resistors called terminators. All other SCSI devices on the bus must have their terminators removed or disabled.
The A5150A host bus adapter is also on the SCSI bus. Termination of the host bus adapter is automatically enabled when it is connected to the end of the bus.
Low-voltage differential peripheral devices are usually terminated with external terminators; however, they are sometimes terminated with jumpers or with a switch on the peripheral. Refer to the peripheral device manual to identify the termination setting of each device and how to change it.
Auto Termination Information
Two versions of the A5150A SCSI PCI Host Bus Adapter (HBA) will be in the field beginning approximately January 2001, with the release of a new version of the HBA. The older HBA has part number A5150-60001 and the new HBA has part number A5150-60101. The new HBA (also known as the jumperless A5150A) does not contain pins and jumpers used for manually configuring auto termination. On the jumperless A5150A, the default power-on setting has auto termination enabled. If you have the older adapter (A5150-60001), do not change the position of the jumpers; leave them as they were when you received the HBA from Hewlett-Packard (open - not jumpered). Auto termination in both A5150A HBAs—the A5150-60001 and the A5150-60101—is now controlled through commands at the Boot Console Handler (BCH) prompt. To use the auto termination feature of both A5150A HBAs, you must have the correct version of the Processor Dependent Code (PDC) on your system. The correct PDC versions are shown in Table 2-3.
