Service Reference Guide, dc5100 376220-001 4–5
Serial and Parallel ATA Drive Guidelines and Features
4.3 PATA Drive Installation Guidelines
Most computer system boards have two or fewer Parallel ATA (PATA) channels with a dedicated
connector for each channel. When two channels are present, one is designated as the Primary and
the other as the Secondary Channel.
Each of the two channels can have up to two devices attached to it. All drives are connected to a
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.
HP does not support the use of PATA (IDE) hard drives when SATA hard drives are installed on
the computer.
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.
4.3.1 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.
General Attach Guidelines
■ The lower the device class number, the faster the device and the more bandwidth required.
■ Drives installed in the Device 0 positions on both the primary and secondary channels
receive the greatest possible bandwidth.
■ The bootable ATA hard drive should always be installed on the primary channel in the
Device 0 position.
Class 1
Hard
Drives
Class 2
High Speed
Optical Drives
Class 3
Optical Storage
Drives
Class 4
Magnetic
Storage Drives
ATA-100
ATA-66
ATA-33
DVD
DVD-CD R/W
R/W CD-ROM
CD-ROM
LS-120
Tape
Zip
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