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In computing, especially in Computers hardware, a controller is a chip (such as a microcontroller), expansion card, or a standalone device that communicates with a larger peripheral device. It may be a connection between two parts of a computer (for example, a memory controller (e.g., that controls memory access for the computer) or a controller in an external device that controls the performance management and communication with that device.

A controller in a computing field is a hardware device or software that manages or directs the data flow between two entities. In computing, controllers can be cards, microchips, or separate hardware devices to control peripherals. Generally, a controller can be thought of as something or someone that is an interface between two systems and manages the communication between them.

This term is sometimes used in the opposite sense to refer to a device by which the user controls the computer, such as a game controller. In desktop computers, the controller may be a plug-in board, an integrated circuit on the motherboard, or an external device. The controller in mainframe computers is usually either a separate device connected to a channel or integrated into the peripheral. Controllers can be on both sides of the computer bus. The controller on the host side is called a host controller or (in storage contexts) a host bus adapter.

The controller on the side (physically part of the peripheral device) is called a peripheral controller. Among them are the disk and flash memory controllers, which are usually integrated into the drive in modern systems. This classification does not apply to network controllers, and neither system is more central/peripheral. Now you may be wondering what a disk controller is? The disk controller connects the disk to an external data bus like an interface. The controller is placed on the main board or in the form of interface cards in the expansion slots of the main board. But what is the hard controller? To answer this question, it can be said that the hard disk controller is a circuit that enables a computer to read and write information on a hard disk.

A hard disk controller also acts as a bus, connecting the computers to the rest of the computer’s components. Today’s hard drives have a controller built into them, usually a circuit that covers the bottom or back. What is a drive controller? Hardware devices and peripherals designed without drive controller devices cannot work properly.
Examples of controllers

Here are some examples of controllers:

• A graphics card is an integrated circuit card in a computer, or some cases a monitor, that provides digital-to-analog conversion, video RAM, and a video controller to send data to the computer screen.
• A game controller is a device for playing games.
• A network interface card (NIC) is a computer circuit board or card that is installed in a computer so that it can connect to a network.
• A WAN Interface Card (WIC) is a specialized network interface card that allows devices to connect to a wide area network.
• The flash controller is a part of the flash memory that communicates with the host device and manages the flash file directory.
• A baseboard management controller (BMC) is a specialized service processor that monitors the physical state of a computer, network server, or other hardware equipment using sensors and communicates
• with the system administrator through independent communication.
• Controller SBC is a device or program that monitors how calls are initiated, executed and terminated in a VoIP (Voice over Internet Protocol) network.
• Primary Domain Controller (PDC) and Backup Domain Controller (BDC) are roles that can be assigned to a server to manage access to a set of network resources (applications, printers, etc.) for a group of users.

Controller boards

Early desktop computers such as the IMSAI 8080 used expansion cards for all controllers, each with a specific type of device. Examples of development board controllers are:

• Graphics controller or video display controller
• SCSI controller
• Network Interface Controller (NIC)
• Parallel port controller

Controller chips

As chip density improved, controllers were implemented as single chips and were often located on the motherboard. Examples of controller chips include the following:

• Microcontroller Unit (MCU)
• Keyboard controller
• Programmable interrupt controller
• Northbridge (computing) – Intel’s memory controller chip
• Southbridge (computing) – Intel I/O control chip
• Universal Asynchronous Receiver/Transmitter (UART) controller chip
• The memory controller is the logic that controls data flow management in a computer system.
• Peripheral DMA controller
• Floppy disk controller

Controller, what is a disk controller? What is a hard drive controller? What is a drive controller?

External controllers

Further integration has enabled the development of Super I/O chips. Individual chips can control devices such as floppy disks, parallel ports, serial ports, keyboards, and mice. The following can be mentioned from external controllers:

Disk controllers are often found in modern disk drives.
A disk array controller, also known as a RAID controller, is a storage controller.
Flash controller or SSD controller manages flash memory.

Main controllers

In most mainstream systems, a device-independent channel typically connects to the CPU and a controller or control unit that implements device-dependent logic for connecting specific devices. The functions performed by the control unit are similar to those performed by a device driver program on smaller systems. Some devices have integrated control units that are logically discrete but are included with the device rather than requiring a separate box. Often a control unit can be connected to several channels connected to single or multiple systems. Some of the main control units are:

IBM 2821 control unit used to connect card reader, punch, and line printer to IBM System / 360 and IBM System / 370 computers.
IBM 270x and IBM 37xx are used for telecommunications.
IBM 3271, 3272, 3271, and 3174 connect terminals (display devices).

Frequently Asked Questions

What is a Controller?

A controller is a chip (such as a microcontroller), expansion card, or a standalone device that communicates with a larger peripheral device and may establish communication between two parts of a computer, managing the performance and communication with that device.

Name the main controller unit?

The main controllers are IBM 2821, IBM 270x, IBM 33xx, IBM 3271, IBM 3272, IBM 3271, and IBM 3174.

Name the controller chips?

Some of the controller chips are as follows:

• Intel memory controller chip
• Intel I/O control chip
• Universal Asynchronous Receiver/Transmitter (UART) controller chip