Bus (computing)

In computer architecture, a bus (historically also called a data highway or databus) is a communication system that transfers data between components inside a computer or, more rarely, between computers. It encompasses both hardware (e.g., wires, optical fiber, bus slots) and software, including communication protocols. At its core, a bus is a shared physical pathway, typically composed of wires or traces on a circuit board, that allows multiple devices to communicate. Unlike networks, which route addressed packets across switches, buses use arbitration protocols to manage which device can transmit data over the shared pathway.

Buses are categorized based on their role, such as system buses (also known as internal buses, internal data buses, or memory buses) connecting the CPU and memory. Expansion buses, also called peripheral buses, extend the system to connect additional devices, including peripherals. Examples of widely used buses include PCI Express (PCIe) for high-speed internal connections and Universal Serial Bus (USB) for connecting external devices.

Modern buses utilize both parallel and serial communication, employing advanced encoding methods to maximize speed and efficiency. Features such as direct memory access (DMA) further enhance performance by allowing data transfers directly between devices and memory without requiring CPU intervention.

Address bus

An address bus is a bus that is used to specify a physical address.