| The bus, as it relates to the pathways on the computer and in the processor, carries the various signals, addresses, and data that move about the PC between its components. The bus is a group of electronic transmission lines that interconnect the components of the CPU, motherboard, and expansion cards. bus structures have different sizes, ranging from 16 to 64 bits on modern microprocessors, which determine the amount of data that can be transmitted. Just as an 8-lane highway carries more traffic than a two-lane road, a 64-bit bus carries more data than a 16-bit bus. |
A PC has several distinct bus structures, the most important of which are: |
| Data bus: Carries data to and from the CPU, main memory, and peripheral devices. The width (in bits) determines the amount of data that can be transmitted at a time. |
Address bus: Carries addresses of data and instructions between memory and the CPU. The width (in bits) determines the size of the address (represented as a binary number) that can be passed over the address bus. |
Control bus: Carries control information, such as the status of the devices, between the CPU and the other devices. The information passed over the control bus provides data that indicates the data is ready to be read, a device is waiting to use the bus, and the type of operation a device is requesting (read, write, interrupt). |