Most motherboards have two parallel , 44 pin IDE interface connectors. These
are used for connecting hard drives (though these PATA (parallel ATA) connections
are rapidly being replaced by SATA (Serial ATA) connections for HDs)
and optical drives, like CD and DVD drives. Up to two devices can be connected
to each IDE port, in a Master/Slave configuration.. A 44 wire ribbon
cable is used for this connection with three connectors, one on each end and
one in the middle (actually a few inches from one end). One end is plugged
into the motherboard connection and the other end is plugged into the first (or
only) device. If two devices are connected the second is connected to the middle
connection. The device plugged into the end must be configured as a master
(usually via a jumper on a set of pins on the device) while the second must be
configured as a slave OR both must be configured as cable select.
Two devices connected on the same IDE port will contend for access to the
bus, this causes a compromise in the speed of the drives. The newer serial ATA
(SATA) interface has four separate slots that allow independent access and this
increases the speed at which hard drives work, though, as of yet, there are few
SATA optical drives available. The cables are also narrower, improving the flow
of air inside the case.
The support for older (PATA) IDE drives is starting to disappear. The
new G/Q/P 965 chipset series from Intel completely dropped support for such
devices. Nevertheless, all motherboard makers are still including an additional
IDE controller on their boards, and it will remain possible to buy an extra PCI
IDE controller.