Computer bus

Computer system bus connects the computer parts

A computer bus (often simply called bus) is part of most computers. Its role is to transfer data, signals, or power between some of the components that make up a computer.

The size or width of a bus is how many bits it carries in parallel. Common bus sizes are: 4 bits, 8 bits, 12 bits, 16 bits, 24 bits, 32 bits, 64 bits, 80 bits, 96 bits, and 128 bits. Computers use such buses to link:

• CPU to on-board Memory
• multiple CPUs in a multi-cpu system
• Arithmetic logic unit to the rest of the CPU
• hard drives, graphics cards, etc. to the main system.

Drives are usually connected by Serial ATA or the earlier ATAPI bus. USB and Firewire connections go to printers and other peripheral devices.

Computer Bus Media

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  Four PCI Express bus card slots (from top to second from bottom: ×4, ×16, ×1 and ×16), compared to a 32-bit conventional PCI bus card slot (very bottom)

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  Simplified diagram of a computer system implemented with a single system bus. This modular organization was popular in the 1970s and 1980s.