data bus

data bus (data path) A group of signal lines used to transmit data in parallel from one element of a computer to another. The number of lines in the group is the width of the data bus, each line being capable of transferring one bit of information. In a mainframe the width of the data bus is typically equal to the word length, i.e. 32, 48, or 64 bits. The data bus used to interconnect LSI components need not have the same width as is used on the chips themselves. For example, a processor with an internal data bus width of 32 bits could be designed to transmit information over an 16-bit-wide external data bus. Such processors are said to use a multiplexed data bus (see multiplexed bus). The wider the data bus, the higher the potential performance of the system, since more information is transmitted in parallel with a wider data bus. Narrower data buses in general degrade performance but are less costly to implement. A multiplexed data bus is often chosen to reduce the number of pins needed on an integrated circuit for the data bus.