50-Pin And 68-Pin Internal Connectors, And 68-Pin External Connector; Scsi Id Setting - Adaptec AHA-2740W User Manual

50-pin and 68-pin Internal Connectors, and 68-pin External Connector

This is an invalid setup; only two of the three SCSI connectors can
have SCSI devices connected at any one time.
Note:
Any configuration utilizing all three SCSI connectors
will result in an improperly terminated SCSI bus.

SCSI ID Setting

Each SCSI device (including the host adapter) located on the SCSI
bus must be set to a unique SCSI ID. The SCSI ID serves two pur-
poses: it uniquely defines each SCSI device's address on the bus, and
it determines the device's priority on the bus during the Arbitration
phase. The Arbitration phase determines which device will own the
bus when two or more devices simultaneously request to use it.
Note:
If any SCSI device is connected to the 50-pin internal
SCSI connector, the host adapter must be assigned a SCSI ID
that ranges from 0 to 7; SCSI ID 7 is recommended.
When selecting the SCSI ID, consider the following:
The default value for your host adapter is SCSI ID 7. Normally,
the host adapter should always be set to SCSI ID 7, which is the
ID that has the highest priority on the SCSI bus.
Standard 8-bit SCSI devices can be assigned IDs that range
from 0 to 7; SCSI ID 7 has the highest priority, and SCSI ID 0
has the lowest.
16-bit Wide SCSI devices and the host adapter can be assigned
IDs that range from 0 to 15. SCSI IDs 0-7 have higher priority
over SCSI IDs 8-15. SCSI ID 7 has the highest priority, and SCSI
ID 8 has the lowest.
You only need to change a device's SCSI ID if it conflicts with
the SCSI ID of another device or another host adapter (assum-
ing they are on the same SCSI bus).
SCSI ID 0 is best reserved for the SCSI hard disk drive that will
be used as your computer's boot device.
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AHA-2740W/2742W/2744W User's Guide
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Current Date: 8/3/94
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ECN Date: 8/9/94
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Getting Started
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