Controller (computing)

In computing and especially in computer hardware, controller is a chip, an expansion card, or a stand-alone device that interfaces with a peripheral device. This may be a link between two parts of a computer (for example a memory controller that 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 mainframes the controller is usually either a separate device attached to an channel or integrated into the peripheral.

Controller chips

• Keyboard controller
• Programmable Interrupt Controller
• Northbridge (computing) – Intel memory controller chip.
• Southbridge (computing) – Intel I/O controller chip.
• Universal asynchronous receiver/transmitter (UART) communications controller chip.
• Memory controller, logic which manages the flow of data in a computer system.
• Peripheral DMA controller.

Controller boards

Video display controller card

• Graphics controller or video display controller
• SCSI controller, more properly called SCSI host bus adapter
• Network interface controller (NIC)

External controllers

Internal disk controller card by Western Digital shown with disk drive

• Disk controller and Floppy disk controller often integrated into modern disk drives.
• Disk array controller, also known as RAID controller, a type of storage controller
• Flash controller or SSD controller, manages flash memory.
• Terminal Access Controller

Mainframe controllers

In IBM terminology a controller is "a device that decodes the [channel] command and effects the operation of the device."

In most mainframe systems a device-independent channel usually attaches to the CPU and a controller or control unit implements device-dependent logic for attaching specific devices to the channel. Some devices have integrated control units.

• IBM 2821 Control Unit, used to attach card readers, punches and line printers to IBM System/360 and IBM System/370 computers
• IBM 270x and IBM 37xx telecommunications control units
• IBM 3271, 3272, 3271, and 3174 3270 control units

See also

• Adapter (computing)
• Programmable logic controller
• Computer bus
• Super I/O
• Control unit (disambiguation)
• MIDI controller

External links

• Controller description at Webopedia, a computer term dictionary.