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 unit CD-ROM Compact Disk – Read- only memory DVD Digital versatile disk RAM Random access memory ROM Read – only memory BIT Binary digit MB Megabyte GB Gigabyte LCD Liquid crystal display DPI 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