Dell 4100/200 manual Installing Scsi Devices in the External Bays, Scsi Configuration Information

The power connectors are keyed to avoid incorrect inser- tion; do not force two connectors together if they do not fit properly.

A ribbon cable (see Figure 9-4) functions as the interface cable for most types of drives.

pull tab	key	colored strip on
	(blocked hole)	ribbon cable

interface connector

header connector key (cut-off pin)

Figure 9-4. Header Connector

Most interface connectors are keyed for correct insertion; that is, a notch or a missing pin on one connector matches a tab or a filled-in hole on the other connector. Keying ensures that the pin-1 wire in the cable (indicated by the colored strip along one edge of the cable) goes to the pin-1 ends of the connectors on both ends. A header con- nector is usually keyed by the omission of one of its pins with the corresponding hole filled in on the connector on the cable (see Figure 9-4).

CAUTION: When connecting an interface cable, do not reverse the interface cable (do not place the colored strip away from pin 1 of the connector). Reversing the cable prevents the drive from oper- ating and could damage the controller, the drive, or both.

DC Power Cables

Each drive in the external drive bays must connect to a

4-wire DC power cable from the system power supply or optional power-supply paralleling board. The connectors on this cable are labeled “FD1,” “FD2,” “FD3,” “FD4,” and “FD5.” Connectors FD1 through FD4 are used for 5.25-inch devices, whereas connector FD5 is used for the standard 3.5-inch diskette drive. Before connecting a drive to a power cable, refer to Figure 9-5 to identify the correct cable connector to use for the drive.

system board

system boardconnector connector

5.25-inch drive	3.5-inch drive
connector	connector

Figure 9-5. DC Power Cable Connectors

Installing SCSI Devices in the External Bays

SCSI devices in the external drive bay (such as CD-ROM drives and tape drives) are controlled by the Ultra/ Narrow SCSI controller on the system board.

SCSI Configuration Information

Although SCSI devices are installed essentially the same way as other devices, their configuration requirements are different. To configure SCSI devices installed in the external bays, follow the guidelines in the following subsections.

Installing Drives in the External Bays 9-3