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Hard disks with an IDE (Integrated Drive Electronics) interface are connected to the
motherboard via a 40- or 80-thread flat marked cable: one of the threads of the
cable is red.
Two IDE hard disks can be connected to each of the sockets, i.e. there can be up to
four hard disks of this type installed in the PC. (There are three plugs on each IDE
cable: two for hard disks and one for the motherboard socket.)
As noted, IDE cable plugs are usually designed so that there is only one way to
connect them to the sockets. Usually, one of the pinholes is filled on the cable plug,
and one of the pins facing the filled hole is removed from the motherboard socket,
so it becomes impossible to plug the cable in the wrong way.
In other cases, there is a jut on the plug on the cable, and an indentation in the
socket of the hard disk and of the motherboard. This also ensures that there only
one way to connect the hard disk and the motherboard.
In the past, this design of plug did not exist, so there was an empirical rule: the
IDE cable is connected to the hard disk socket so that the marked thread
is the closest to the power cable, i.e. the marked thread connected to pin #1 of
the socket. A similar rule was used for connecting cables with the motherboard.
Incorrect connection of the cable with either the hard disk or the motherboard does
not necessarily damage the electronics of the disk or the motherboard. The hard
disk is simply not detected or initialized by BIOS.
There are some models of hard disks, especially the older ones, for which incorrect
connection damaged the electronics of the drive.
We will not describe all the types of hard disks. Currently the most widespread are those
with IDE or SCSI interfaces. Unlike IDE hard disks, there can be from six to 14 SCSI hard
disks installed in your PC. However, you need a special SCSI controller (called a host
adapter) to connect them. SCSI hard disks are not usually used in personal computers
(workstations), but are found mostly in servers.
Aside from an IDE cable, a four-thread power cable must be connected to the hard
disks. There is only one way to plug in this cable.
B.1.3
Installation modes, jumpers
A hard disk can be installed in a computer as master or as slave. The mode of hard
disk installation is defined by the position of special connectors (called jumpers) on
the hard disk.
The jumpers are either located on the electronic board of the hard disk or a special
socket that provides for the connection of the hard disk and the motherboard.
There is usually a sticker on the drive that explains the markings. Typical markings
are DS, SP, CS and PK.
Each jumper position corresponds to one hard disk(s) installation mode:
•
DS – master/factory default
•
SP – slave (or no jumper required)
•
CS – cable select for master/slave: the purpose of the hard disk is determined by
its physical position with respect to the motherboard
•
PK – jumper parking position: the position where one can put the jumper if it is
not necessary in the existing configuration
Copyright © Apricorn, Inc., 2000-2007
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