Owner`s manual
Page A-8 Appendix A
AMOS computers using the 50-pin SASI bus, which includes non-SCSI-2
enhanced AM-1000, AM-1200, AM-1400, AM-1600, AM-2000, AM-2000M,
AM-3000, and AM-3000M computers, require that one of the internally
mounted peripherals be configured to supply termination power to the
SCSI bus.
A.3.1SCSI-2 Bus Termination Power Guidelines
Use these guidelines for supplying termination power to AM-4000 computers,
Roadrunner enhanced computers, AM-540 enhanced AM-3000M computers, etc:
1.AMOS based computers with SCSI-2 implementation will be configured
with the host controller supplying termination power to the SCSI bus.
2.When the SCSI host controller is supplying termination power, you want
your internally mounted SCSI peripherals to be configured so they do not
supply termination power.
3.If a computer with one or more SCSI peripherals is cabled to a subsystem
with additional SCSI devices, the SCSI devices in the subsystem should
be configured so they do not supply termination power. Ideally, you want
the SCSI host controller in the main system to be the sole source of
termination power.
The termination power guidelines described above are valid even when you are using
SCSI peripherals that do not support SCSI-2 protocol.
The SCSI host controller on AM-190 and AM-540 boards is permanently configured to
supply termination power to the SCSI bus. On Roadrunner boards, the termination
power feature can be enabled or disabled by setting a jumper. As of 07/26/94, Alpha
Micro began configuring all Roadrunner boards with termination power enabled. See the
Roadrunner installation instructions for information on how to configure the termination
power jumper.
A.3.2SASI Bus Termination Power Guidelines
Use the following guidelines to determine which peripheral will be used to supply
termination power for the 50-pin SASI bus:
1.Whenever possible, only one SCSI peripheral will be configured to supply
termination power to the SASI bus.
2.If a computer has more than one SCSI peripheral and at least one of those
peripherals is a disk drive, one disk drive will be configured to supply
termination power to the bus. The other disk or tape SCSI devices will be
configured so they do not supply termination power.
PDI-03500-50, Rev. B00