Hardware Reference
In-Depth Information
To learn more about the VL-Bus, see “
The VESA Local Bus
” in
Chapter 4
,
“
Mother-
on the DVD packaged with this topic.
The PCI Bus
In early 1992, Intel spearheaded the creation of another industry group. It was formed
with the same goals as the VESA group in relation to the PC bus. Recognizing the need
to overcome weaknesses in the ISA and EISA buses, the PCI Special Interest Group was
formed.
The PCI bus specification was released in June 1992 as version 1.0 and since then has un-
dergone several upgrades.
Table 4.55
shows the various releases of PCI.
Table 4.55 PCI Specifications
PCI redesigned the traditional PC bus by inserting another bus between the CPU and the
native I/O bus by means of bridges. Rather than tap directly into the processor bus, with
its delicate electrical timing (as was done in the VL-Bus), a new set of controller chips
was developed to extend the bus, as shown in
Figure 4.39
.
Figure 4.39
Conceptual diagram of the PCI bus.
