| | | | The common transmission pathways between different components of a computer. Wires or connections on a PCB that connect i) the processor to the memory in the case of the Front Side Bus (FSB), also known as the System Bus or Local Bus and ii) peripherals such as devices attached via PCI, USB connections via one or more External Buses. Buses may be either serial or parallel, in which the data is striped across multiple wires. It is not known exactly how the term arose, but it is thought it may have been coined because of the similarity with the way the vehicle drops off and picks up passengers along it's route. All signals travel along the same pathway but only those devices addressed by the signals pay attention to them, the rest ignore them. A bus consists of two components, namely the data bus that transmits the data and the address bus that carries information about which devices the signal refers to and is relevant to. Two factors about buses are critical - their speed and "width". The former determines how fast data travels down the bus and the latter how much data can travel at a time. Bus speed is measured in MHz (for example 400MHz, 800MHz+ for the front side bus of modern PCs) and often the most important pathways, such as the local bus connecting directly to the processor, run at a faster clock speed. The bus width refers to how many bits of data can move along the bus together e.g. a 32-bit bus can transmit 32 bits at a time and a 64-bit bus, 64. | | | |
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