Working Inside Your Computer 6-79
The flat ribbon cables are the interface cables for internal
drives. These interface cables are described in more
detail in Chapter 8, “Installing Drives in the External
Bays,” and Chapter 9, “Installing Drives in the Internal
Bays.”
The system board—the large, vertical printed circuit
board at the right side of the chassis—holds the com-
puter’s control circuitry and other electronic components.
Hardware options are installed directly onto the system
board in the Peripheral Component Interconnect (PCI) or
Extended Industry-Standard Architecture (EISA) expan-
sion-card connectors. The external drive bays provide
space for up to three half-height drives—typically a dis-
kette drive is installed in the top bay, a CD-ROM drive in
the middle bay, and the bottom bay is reserved for an
optional drive (often a tape drive for backing up data
from the hard-disk drives). The internal drive bays pro-
vide space for up to three 3.5-inch small computer system
interface (SCSI) hard-disk drives. Drives installed in the
internal drive bays can be up to 1.6 inches high.
During an installation procedure, you may be required to
change a jumper or switch setting on the system board, on
an expansion card, or on a drive. For more information, see
“Jumpers—A General Explanation” in Appendix B.