The bus, as it relates to the pathways on the computer and in the processor, carries the various signals, addresses, and data (remember, data is plural) that are transferred around the computer between its components. Although quite dissimilar, it can be related to the routes of your local transit company in many ways.
On the computer, a bus structure is a group of electronic transmission lines that connect the various components of the CPU, motherboard, and expansion cards to each other. Bus structures have different sizes, ranging from 16 to 64 bits on modem microprocessors, and their size determines the amount of data that can be transmitted. Obviously, a 64 bit bus carries more data than a 16 bit bus.
Within the computer, there are several bus structures, as illustrated in Figure 3 4. The most important of these are as follows:
Data bus Carries information to and from the CPU.
Address bus Carries the address from where data is to be read to where data is to be written.
Control bus Carries the signals used by the CPU and the other components of the computer to communicate with each other, including when data is ready to be read, when another device wishes to use the bus, and the type of operation to be performed (read, write, interrupt).
