Controller (computing)

Controllers are electronic units of computer hardware that control certain processes. If these units consist of only one integrated circuit, they are usually called microcontrollers.

Controllers have a variety of tasks in the computer: They take over the processing of interrupt requests (IRQs), keyboard input or the control of accesses to the hard disk (see e.g. ST506 interface).

In common parlance controllers or often also called adapters usually denote an interface, e.g. network controller/~adapter denotes the component that connects a PC to a network and graphics controller/~adapter, the one that connects the PC to some image output device.

In common parlance, however, components for hard disk connection that are called controllers (e.g. IDE controllers) are nowadays mostly host bus adapters. The controllers of hard disks in the actual sense have been housed in the hard disk itself since the spread of Integrated Drive Electronics (IDE) in the 1980s; for SCSI hard disks this has been true from the beginning anyway.

In PCs, controllers are located on plug-in cards or the motherboard of the computer itself. Since the keyboard controller is one of the elementary functions of the computer, it is always on the motherboard.

See also

• Interrupt controller
• embedded controller
• Memory controller