Controller (computing): Difference between revisions

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{{Refimprove|date=October 2012}}

In [[computing]] and especially in [[computer hardware]], a '''controller''' is a [[Integrated circuit|chip]], an [[expansion card]], or a stand-alone device that [[interface (computing)|interface]]s with a more [[peripheral]] device. This may be a link between two parts of a computer (for example a [[memory controller]] that [[memory management|manages access to memory]] for the computer) or a controller on an external device that manages the operation of (and connection with) that device.

The term is sometimes used in the opposite sense to refer to a device by which the user controls the operation of the computer, as in ''[[game controller]]''.

In desktop computers the controller may be a plug -in board, a single integrated circuit on the [[motherboard]], or an external device. In [[mainframe computer|mainframes]] the controller is usually either a separate device attached to a [[Channel I/O|channel]] or integrated into the peripheral.

==Host and peripheral controllers==

Controllers can be present on both sides of a [[computer bus]]. The controller on the host side (physically part of the host) is called a '''[[host controller]]''' or (in storage contexts) a '''host bus adapter'''. The controller on the peripheral side (physically part of the peripheral device) is called a '''peripheral controller'''; examples are [[disk controller]]s and [[flash memory controller]]s, which in modern systems are usually integrated into the drive.

This classification does not apply to [[network controller]]s, since systems participate as peers and neither system is clearly more central/peripheral.

==Controller boards==