Power Computing PowerCenter PRO User Manual page 50

Connecting Peripheral Devices
approximately 110-ohm impedance. Most SCSI problems are the result of low-
grade cables. Of the SCSI cables our engineers have tested, Apple and APS
cables are recommended for consistent reliability.
Note: External SCSI devices which are connected to the computer have
independent power systems and must be turned on and off at the device;
internal SCSI devices are powered by the computer and turn on and off when
the computer does. Devices on the SCSI bus which are turned off can cause
system errors.
To connect an external SCSI device:
1. Shut down the computer and the SCSI device.
2. Make sure that the device has a unique SCSI ID from 0 to 6.
For details, see Setting the SCSI ID on page 17.
3. Connect the device to the computer's SCSI port or to the last device
in the chain, using the appropriate cable.
4. Make sure that the last device in the chain is terminated.
Some devices require an external terminator, while others are internally
terminated. Active termination is recommended for external SCSI chains,
as it reduces noise and increases reliability.
When you are ready to start up, turn on your SCSI devices before you turn on
the computer. If you do not, your computer will not recognize the devices.
Connecting an internal SCSI device
You install internal SCSI devices in one of the computer's internal storage bays.
See Chapter 7, Installing Internal Drives, on page 85 for instructions on
installing internal SCSI devices.
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PowerCenter Pro User's Guide
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