HP D530 HP Compaq Business Desktop d500 Service Reference Guide, 5th Edition - Page 56
PATA Device Classes, General Attach Guidelines
UPC - 808736649308
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Serial and Parallel ATA Drive Guidelines and Features Any drive attached to a channel must have a drive designation. If only a single drive is connected to a channel and its jumper is in the cable-select position, it is designated as the primary drive (Drive/Device 0) by its attachment to the Drive/Device 0 cable position. If two cable-selected drives are connected to a single channel, one will be designated by its attachment to the cable as the primary (Drive/Device 0) and the other as secondary (Drive/Device 1). For optimal performance of a computer system, all drives need to be attached to the ATA channel 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. Class 1 Hard Drives ATA-100 ATA-66 ATA-33 Class 2 High Speed Optical Drives DVD DVD-CD R/W Class 3 Optical Storage Drives R/W CD-ROM CD-ROM Class 4 Magnetic Storage Drives LS-120 Tape Zip 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. 4-4 336492-005 Service Reference Guide, d500