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Hard Drives
SCSI Drives
IDE Drives
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Basics
Hard Drive
Basics IDE Drives - 1


IDE Drives
Intelligent drive electronics, IDE, incorporates controller
hardware into the drive. IDE is offered in 8- and 16-bit
interface types. Eight-bit drives are sometimes referred to
as XT interface drives, and 16-bit drives are sometimes
referred to as AT interface drives.

IDE drives do not use a SCSI bus. Apple computers continue
to use an external SCSI chain, which is supported by a SCSI
chip on the logic board.

Also, Apple's HD SC Setup works with IDE drives.
Basics WIDE and FAST SCSI Protocols - 2


WIDE and FAST SCSI Protocols
SCSI chains that use SCSI-2 protocols are faster than SCSI
chains using the original SCSI protocols. Two terms used in
the SCSI-2 protocol are "WIDE" and "FAST."

The term "WIDE" defines the 2-byte or 4-byte wide data
interface where each data byte uses its corresponding parity
bit. The traditional SCSI-1 interface protocol is 1 byte
wide. "FAST" SCSI is defined as data transfer rates between
5 MHz and 10 MHz.

Check these protocols against individual drives for
comparative data.

Devices using the SCSI-2 WIDE and FAST protocols are
compatible with existing SCSI-1 devices.
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Troubleshooting
Hard Drive
Troubleshooting General/ - 1


General
The Symptom Charts included in this chapter will help you
diagnose specific symptoms related to your product. Because cures
are listed on the charts in the order of most likely solution, try
the first cure first. Verify whether or not the product continues to
exhibit the symptom. If the symptom persists, try the next cure.
(Note: If you have replaced a module, reinstall the original module
before you proceed to the next cure.)

If you are not sure what the problem is, or if the Symptom Charts
do not resolve the problem, refer to the Flowchart for the product
family.

For additional assistance, contact Apple Technical Support.
Troubleshooting HD SC Setup/ - 2


HD SC Setup
Before you replace any drive hardware, run HD SC Setup to
update the driver on the drive.

HD SC Setup works with SCSI and IDE drives.
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Upgrades
Hard Drives
Upgrades Drives in Quadra 900/950 - 1


Drives in Quadra
Hard Drive Carrier
Hard Drive Mechanism 900/950
SCSI Select There are three general
Cable
procedures for preparing
Termination
Resistors hard drives for Quadra 900/
950 computers: