LOCAL BUS

Bus

When referring to a computer, the bus also known as the address bus, data bus, or local bus is a data connection connection between two or more devices connected to the computer. For example, a bus enables a computer processor to communicate with the memory or a video card to communicate with the memory.

A bus is capable of being parallel or a serial bus and today all computers utilize two types of buses, an internal or local bus and an external bus. An internal bus enables a communication between internal components such as a computer video card and memory and an external bus is capable of communicating with external components such as a SCSI scanner.

A computer or devices bus speed or throughput is always measured in bits per second or megabytes per second.

All buses consist of two parts -- an address bus and a data bus. The data bus transfers actual data whereas the address bus transfers information about where the data should go.

The size of a bus, known as its width, is important because it determines how much data can be transmitted at one time. For example, a 16-bit bus can transmit 16 bits of data, whereas a 32-bit bus can transmit 32 bits of data.

Every bus has a clock speed measured in MHz. A fast bus allows data to be transferred faster, which makes applications run faster. On PCs, the old ISA bus is being replaced by faster buses such as PCI.

Nearly all PCs made today include a local bus for data that requires especially fast transfer speeds, such as video data. The local bus is a high-speed pathway that connects directly to the processor.

Several different types of buses are used on Apple Macintosh computers. Older macs use a bus called NuBus, but newer ones use PCI.

In networking, a bus is a central cable that connects all devices on a local-area network (LAN). It is also called the backbone.