Page 38 - UNI 101 Computer Science Handout.

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Figure 10 PCI Bus Connections

One end of each lane is connected to an I/O device controller, or perhaps to a controller for another

bus. The other end of each lane is connected to a shared switch that is capable of connecting any two

pairs of lanes together. The controller also provides connections between the serial lanes, the system

bus, and the memory bus, converting the format as necessary between serial and parallel. The controller

can use multiple lanes to achieve higher data rates where necessary. The switch is similar to those used
in networking. Many new computer systems are adopting this technology to achieve the high

throughput being demanded by today’s customers, particularly in the area of video display.

BUSES

Bus Characteristics

The physical connection that makes it possible to transfer data from one location in the computer

system to another is called a bus. The CPU and memory work together, it is probably already obvious to

you that there must be a bus of some kind linking the CPU and memory; similarly, buses internal to the
CPU can be used to link registers together at the proper times to implement the fetch-execute cycles.

Specifically, a bus may be defined as a group of electrical, or, less commonly, optical, conductors suitable

for carrying computer signals from one location to another. The electrical conductors may be wires, or
38 Academic Year 2025/2026