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Serial and Parallel ATA Drive Guidelines and Features
4.4.2 PATA Power Cable
Pin
1
2
3
4
4.5 PATA Drive Installation Guidelines
The computer system boards for these products have one Parallel ATA (PATA) channel with a
single connector. The channel can have up to two devices attached to it. All drives are connected
to the channel using an industry-standard 80-conductor cable.
✎
The industry-standard 1.44 MB diskette drive has its own separate channel and is not included as
a part of the maximum four drives.
Each drive attached to a channel must have a drive designation. If a drive is attached to the
Device 0 cable position and its cable-select jumper is present, the drive is designated as Device 0.
Similarly, if a drive is attached to the Device 1 cable position and its cable-select jumper is
present, the drive is designated as Device 1.
For optimal performance of a computer system, all drives need to be attached to the PATA
channel(s) in a specified sequence. This sequence is determined by the device class of the drives
and by specific attach sequence rules.
4.5.1 PATA Device Classes
In order to determine the best drive attach sequence, ATA/ATAPI drives are segregated into four
different classes based upon the bandwidth demands they place on an ATA channel. The most
demanding devices are in Class 1 and the least demanding are in Class 4.
Class 1
Hard
Drives
Supported
only on USDT
chassis with
MultiBay
General Attach Guidelines
■
The lower the device class number, the faster the device and the more bandwidth required.
■
Drives installed in the Device 0 position receive the greatest possible bandwidth.
■
The bootable ATA hard drive should always be installed in the Device 0 position.
4–4
Usage
+12 V
Ground
Ground
+5 V
Class 2
High Speed
Optical Drives
DVD
DVD-CD R/W
390742-001
Class 3
Optical Storage
Drives
R/W CD-ROM
CD-ROM
Service Reference Guide, dc7600
Class 4
Magnetic
Storage Drives
Zip
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