The buses on a computer system are sets of wires that carry information to or from memory or I/O devices. They may be uni-directional (data travels one way) or bi-directional (data travels both ways).
Buses can be seen on the computer motherboard as parallel metal tracks. When the buses leave the motherboard to travel to a component such as a hard disk cables like these are used.
In general the number of wires on the bus corresponds to the width of the bus on the CPU.
Computer systems have several buses dedicated to specific tasks.
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