Block diagram of basic computer By Christabel 10QPL

Central processing unit (CPU)

Storage devices

Output devices

Input devices

Knowledge of i.c.t components

CPU Central processing unit VDU Visual display unitCD-ROM Compact Disk – Read- only memory DVD Digital versatile diskRAM Random access memoryROM Read – only memory BIT Binary digit MB Megabyte GB Gigabyte LCD Liquid crystal displayDPI Dots per inch OCR Optical character recognition SVGA Super video graphics array PPM Pages per minute CD-R Compact disk – recordable CD-RW Compact disk rewritable WORM Written – once read only GUI Graphical user interface WIMP Window, icons , menus , pointers

Desktop (PC)

CD ROM Input DVD drive – backing store or input/ output

Visual Display Unit (VDU) – Output

Speakers – input

Central Processing Unit (CPU)

Mouse - input

Keyboard – Input Central Processing UNIT (CPU)

Input Devices

Keyboards

• Has a standard QWERTY layout.

• Used to enter large amounts text into the computer

• The speed of input depends on the human operator

• Can be slow compared with other input devices

Mouse • Also referred to a ‘pointing device

• Designed to fit under the hand.

• When it is moved a pointer on the screen moves in the same direction

• A ball moves and built-in sensors pick up the movements and send corresponding.

• Easy to use • Inexpensive compared

with other input devices• Experienced users may

find using a mouse slow compared.

Joystick • Allow the user to control the movement of cursor on the screen by moving a different directions

• Usually has a buttons that allow actions to be carried out

• Used to play computer games (in this context it may be referred to as a games paddle

• Easier to use than a mouse.

• Can be expensive –more than a mouse

• A light touch on the joystick gives speedy input