Bus – What is a computer Bus?

A bus in a computer is a data connection between devices connected to the computer. Buses are used to transfer data between components.

Types of computer buses

Computer buses are divided into 3 main buses.

Address bus – It contains information about the location/ address of the data.

Data bus – It allows data to travel between different components of a computer attached with each other through data bus.

Control bus – It controls how and when the data has to be transferred between the components through buses.

Expansion Bus It is used to connect to the outer devices through expansion slots.

On the basis of their positions buses are of two types

Internal bus – The internal data bus, memory bus, system bus or Front-Side-Bus, connects all the internal components of a computer, such as CPU and memory, to the motherboard. They are also referred to as a local bus.

External bus – The External Bus Interface is for interfacing small peripheral devices like flash memory with the processor. It is used to expand the internal bus of the processor to enable connection with external memories or other peripherals.

Width of Bus

There are different sizes, or widths of data buses found in computers today. A data bus’ width is measured by the number of bits that can travel on it at once. The speed at which its bus can transmit data, that is, its bus BANDWIDTH, crucially determines the speed of any digital device. One way to make a bus faster is to increase its width.

How Does Computer Bus Work?

A bus is a connection between two components. It transfers data from one component to the other. It can either be the copper lining on printed circuit board (motherboard) or the wires connecting two components.

A bus transfers electrical signals from one place to another. Data travels between the CPU and memory along the data bus. The location (address) of that data is carried along the address bus. A clock signal which keeps everything in synch travels along the control bus.

More on Buses

USB (Universal Serial Bus)

It was designed for providing both communication and electric power to the connected peripherals like keyboards, digital cameras, printers, disk drives, network adapters, and other devices that can be connected through USB.

There have been three generations of USB specifications:

  • USB 1.0 supports data transfer rates of 12 Mbps
  • USB 2.0 – supporting a transfer rate of up to 480 megabits per second (Mbps), or 60 megabytes per second (MBps).
  • USB 3.0 – supports transfer rates up to 5.0 gigabits per second (Gbps), or 640 megabytes per second (MBps)

PCIe (Peripheral Component Interconnect Express)

PCI Express was designed as a high-speed replacement for the aging PCI and AGP standards. The data transmitted over PCI Express is sent over wires (called lanes). Each lane is capable of transfer speeds around 250 MB/s and each slot can be scaled from 1 to 32 lanes.


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