A bus is a set of physical links (cables, printed circuit tracks, etc.) that can be used in common by several hardware elements in order to communicate. Buses reduce the number of channels needed for communication between different components by using a single data channel.
More specifically, a hardware port is a line that is only used for communication between two hardware components: serial port, parallel port, etc.
A bus is characterized by its maximum throughput (or maximum transfer rate), i.e. the quantity of data it can transmit per unit of time. The maximum data rate is obtained by multiplying the width of the bus by its frequency:
- width refers to the amount of information a bus can transmit simultaneously. The width is expressed in bytes (bits). This volume corresponds to the number of physical lines on which the data are sent simultaneously. A 32-wire network allows 32 bits to be transmitted in parallel;
- the frequency (expressed in Hertz) defines the speed of the bus, i.e. the number of data packets sent or received per second.
A 16-bit wide bus, clocked at a frequency of 133 MHz has a throughput equal to 2 128 x 106 bits/sec