The system bus is a cable which carries data communication among the major components of the computer, as well as the microprocessor. Not all of the communication that uses the bus occupies the CPU, although naturally the examples used in this tutorial will centre on such instances.
The system bus consists of three different sets of wiring, called the data bus, control bus and address bus. These all have divide responsibilities and characteristics, which can be as follows:
Control Bus
the control bus carries the signals involving to the control and co-ordination of the variety of activities across the computer, which can be sent from the control unit within the CPU. Different architectures result in differing number of lines of wire in the control bus, as each line is used to perform a detailed task. For example, different, specific lines are used for each of read, write and reset requests.
Data Bus
This is used for the replace of data between the processor, memory and peripherals, and is bi-directional so that it permits data flow in both directions along the wires. Once more, the number of wires used in the data bus (at times known as the ''width'') can differ. Each and every wire is used for the transfer of signals equivalent to a single bit of binary data. As such, a greater width allows greater amounts of data to be transferred together.
Address Bus
the address bus contains the connections among the microprocessor and memory that carry the signals relating to the addresses which the CPU is processing at that time, for example the locations that the CPU is reading from or writing to. The width of the address bus corresponds to the maximum addressing capability of the bus, or the largest address within memory that the bus can work with. The addresses are transferred in binary format, with each line of the address bus carrying a single binary digit. Consequently the maximum address capacity is equal to two to the power of the number of lines present (2^lines).