Keyboard controller (computing)
Encyclopedia
In computing, a keyboard controller
is a device which interfaces a keyboard
to a computer
. Its main function is to inform the computer when a key is pressed or released. When data from the keyboard arrive, the controller raises an interrupt
(a keyboard interrupt) to allow the CPU to handle the input.
If a keyboard is a separate peripheral device wired to the system unit (such as in most modern desktop computer
s), then keyboard controller is not actually attached to keys' circuits, but receive scancode
s from a microcontroller
embedded to keyboard via some kind of serial interface. In this case the controller also should control keyboard's LED
s by sending data back to keyboard through the wire.
Early PCs used Intel 8042 chip to interface to the keyboard. In computers with a PS/2 connector
the keyboard controller is integrated with mouse
controller.
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...
is a device which interfaces a keyboard
Keyboard (computing)
In computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...
to a computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
. Its main function is to inform the computer when a key is pressed or released. When data from the keyboard arrive, the controller raises an interrupt
Interrupt
In computing, an interrupt is an asynchronous signal indicating the need for attention or a synchronous event in software indicating the need for a change in execution....
(a keyboard interrupt) to allow the CPU to handle the input.
If a keyboard is a separate peripheral device wired to the system unit (such as in most modern desktop computer
Desktop computer
A desktop computer is a personal computer in a form intended for regular use at a single location, as opposed to a mobile laptop or portable computer. Early desktop computers are designed to lay flat on the desk, while modern towers stand upright...
s), then keyboard controller is not actually attached to keys' circuits, but receive scancode
Scancode
A scancode is the data that most computer keyboards send to a computer to report which keys have been pressed. A number, or sequence of numbers, is assigned to each key on the keyboard.- Variants :...
s from a microcontroller
Microcontroller
A microcontroller is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Program memory in the form of NOR flash or OTP ROM is also often included on chip, as well as a typically small amount of RAM...
embedded to keyboard via some kind of serial interface. In this case the controller also should control keyboard's LED
LEd
LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....
s by sending data back to keyboard through the wire.
Early PCs used Intel 8042 chip to interface to the keyboard. In computers with a PS/2 connector
PS/2 connector
The PS/2 connector is a 6-pin Mini-DIN connector used for connecting some keyboards and mice to a PC compatible computer system. Its name comes from the IBM Personal System/2 series of personal computers, with which it was introduced in 1987...
the keyboard controller is integrated with mouse
Mouse (computing)
In computing, a mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons...
controller.