# What is a computer?

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This is a supplemental lesson in the course Introduction to Computers, which is a part of The School of Computer Science

## Objective

Familiarize the student with the basics of computers. This should give the student a stepping stone to use when learning more specific details about computer hardware.

## What is a Computer?

A computer is an electronic device that takes input or output such as numbers, text, sound, image, animations, video, etc., processes it, and converts it into meaningful information that could be understood, presenting the changed input (processed input) as output. All numbers, text, sound, images, animations, and video used as input are called data, and all numbers, text, sound, images, animations, and video returned as output are called information.
A computer is composed of five crucial parts:
* An input device
* A storage facility to hold numbers for processing
* A processor or number calculator
* A control unit to direct tasks to be performed
* An output computer

## Keyboard (not all are the same)

* Keyboard with a Swedish layout
* Keyboard with Danish layout
* Optimus-113 keyboard with color screens in each key
* Apple keyboard with German layout
* Symbolics space-cadet keyboard
* A computer will process data differently based on the kind of data being handled, using a set of instructions called a program or routine.
* A keyboard is also used to give commands to the operating system of a computer, such as Windows' Control-Alt-Delete combination, which brings up the system security options screen. A command-line interface is a type of user interface navigated entirely using a keyboard, or some other similar device that does the job of one.

## Computer Case

The CPU, motherboard, memory, and any internal components are typically put into a computer case/housing.
* Macintosh Performa 6400
* Power Macintosh 7600
* Power Macintosh 8100
* Power Macintosh 8200
* Fujitsu-Siemens Celvin-1
* Open computer case with visible hardware
* The control unit, ALU, and registers are collectively known as a central processing unit (CPU). Early CPUs were composed of many separate components but since the mid-1970s CPUs have typically been constructed on a single integrated circuit called a microprocessor.

## Monitor

* A computer monitor is the most commonly used graphical output device, for the information processed by the CPU.
* A Fujitsu computer monitor
* A CRT computer monitor
* KDS XFlat monitor, screen
* LCD, SyncMaster 710

## Computer System

The minimum requirements for a functional computer system include; a keyboard, a case/ housing containing a CPU and memory (although the case itself isn't strictly necessary), and a monitor. The data is usually entered via the keyboard and the information is usually presented through a screen; however, information can also be presented through speakers, braille displays, or any other output devices.
The way components inside a computer fit together helps describe how the computer works. Data comes in through an Input Device, and is sent to the CPU by Memory. The CPU processes the data, based on the input data and the program which is installed in the computer memory. When the CPU has finished processing the data, it is presented through the output device as information. The information can be stored in the computer memory or presented through an Output Device.

## See Also

* Introduction to Computers
* IT Fundamentals