Compaq 270680-003 Compaq Reference Guide Deskpro 4000 and Deskpro 6000 Series - Page 106

Installing Additional Drives Desktop computers support up to four drives. They may be installed in various configurations, as shown and described in Chapter 1, "Your Computer at a Glance." When installing additional drives, follow these guidelines: s For optimal performance, connect hard drives to the primary controller. Connect expansion devices, such as CD-ROM, IDE tape, and diskette drives to the secondary controller. s You may install either a third-height or a half-height drive into a half-height bay. s You must install one guide screw to ensure the drive will line up correctly in the drive cage. Compaq has provided extra guide screws, installed in the front of the computer chassis, under the front bezel. Some options use M3 metric thread hardware. The Compaq-supplied metric screws are black. Using the Cable-Select Feature with Ultra ATA Devices Optional drives are available from Compaq in kits that include a special drive cable. The configuration of the drives employs a cable-select feature that identifies the drives as device 0 (primary drive) or device 1 (secondary drive). The system board determines which drive is device 0 or device 1, based on the way the drives are connected to the special drive cable. The device 0 drive is the drive connected to the short segment of the drive cable (or that connector closest to the system board); the device 1 drive is the drive connected to the long segment of the drive cable. The device 0 and device 1 identities are used by the system to distinguish between the two drives. The installation requires no jumper setting changes on the existing or optional drives. All Compaq drives have the jumpers preset for cable-select installation.  If installing a second device on the primary controller, you must use an 80-conductor Ultra ATA cable for optimal performance. This cable is available as a Compaq option. 6-24 Upgrading the Desktop Computer