The Functional Unit of PC has the following components - CPU (Central Processing Unit), Monitor/VDU (Visual Display Unit), Key Board, Mouse, Printer (Hard Copy Output Devices), Memory Unit i) CPU (Central Processing Unit): It is System Unit (chassis) & compulsory for a computer. On this all other hardware components (Mother board, Processor, Floppy drive, CD drive, Sound Card etc.) of the computer rests. It is the main working unit.
ii)Monitor/VDU (Visual Display Unit): It is a TV Screen. It displays objects. The size of the screen varies from 8 inches up to 21 inches and can display a maximum of 24 lines of 80 characters so that a full screen can display up to 1920 characters in a matter of a few seconds. There are various types of display adapters used as monitors such as –
MDA – Monochrome display Adapter.
CGA – Color Graphic Adapter.
EGA – Enhanced Graphic Adapter.
VGA – Video Graphic Adapter.
LCD -- Liquid Crystal Display.
LED – Light Emitting Diode.
Picture element of the monitor is called Pixel Monitors can work on any one of the following modes. I) Text mode- here, unit of display is character and not dots. ii) Graphics mode – here unit of display is dot. And each dot can be controlled.
iii)Key Board: it is an input device and is compulsory unit it has 84 or 108 keys. The key is classified as follows:
1) As Basic “QWERTY” keys – from character A to Z keys.
2) Numerical Keys – from 1 to 10 keys.
3) Functional keys – from f1 to f12 keys.
4) Special keys – ALT, CTRL, mouse keys etc.
The keyboard contains a processor of less strength. Whenever a key is pressed this processor gets a signal and sends a number called scan code to the keyboard controller located on the motherboard. The BIOS program of the operating system receives this scan code. This program of the BIOS is called driver.
iv) Mouse: It is a hand held input device and is optional. It is also known as pointing device. With this an operator can have access to any dot. It is generally used for graphics. We can move the cursor anywhere with the help of mouse. It is indicated by arrow on display board. There are two types of mouse 1) Two-Button Mouse. 2) Three Button Mouse. The operator normally uses cursor to pin point a particular position on the screen. The cursor can be moved along a line in both right and left hand side of vertically up and down.
v) Printer (Hard Copy Output Devices): It is an output device and is optional. Anything tangible is termed, as hard is computer science. So hard copy means copies of matters on paper or from. Generally a printer or a plotter is used for the purpose. A printer is used for printing characters while a plotter is used for creating graphics.
vi) Memory Unit: This unit is used to store information and data. Memory unit is also some times referred to as Storage Units. This storage of a computer is of two types. Main storage of Main memory and Backup storage of Secondary memory or External Storage.
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