UPGRADING REPAIRING PCs

Expansion Slots 67
While AGP video is standard on all desktop systems today, it is
often implemented on very low-cost systems by means of
onboard video rather than an AGP slot.
Table 2.25 provides a visual quick reference for expansion slots
found in modern PCs.
Figure 2.22 The AGP slot is located at the first (inside) slot position on
motherboards with an AGP slot. Note the lack of space between the last PCI
slot and the first ISA slot. This is called a combo or shared slot; only one of
the slots can actually be used.
Table 2.25 Expansion Slot Quick-Reference Table
Slot Type Bus Speed Bus Width Best Use
ISA 8.33MHz 8-bit or 16-bit Modems, serial, parallel
ports; will be phased out in
early twenty-first century
EISA 8.33MHz 32-bit with Obsolete for most uses;
EISA cards; works well with servercompatible
with ISA cards
optimized NIC cards
MCA 10MHz 16-bit or 32-bit Introduced with IBM
MicroChannel PS/2s in 1987;
obsolete
VL-Bus 25–33MHz 32-bit; slot also Obsolete; was popular for
typical; can can be used video cards and IDE hard
be run up
to 40MHz
on some
systems
as ISA disk interfaces
PCI 25–33MHz Most are 32-bit; Video, SCSI, sound,
(depends some 64-bit modems; replaced ISA
on speed implementations as general-purpose bus