1. 1 CHAPTER 2 Hardware

2. 2 CPU : Central Processing Unit -Every PC system unit contains at least one chip called microprocessor (cpu) attached on motherboard. -The cpu follow the instructions to process the data to produce the information

3. 3 Parts of the cpu 1- arithmetic and logic unit (ALU): perform arithmetic operations and logical operations -arithmetic (a= 5+4) - Logic (a > b) 2-Registers: are immediate memory location used by the ALU to store the data in execution. 3- control unit (CU): tells the rest of the computer system how to carry out the instructions, it moves the electronic signals (data) between main memory and arithmetic unit and between the MM and input/ output devices.

4. 4 Input devices -Allow you to input information to the computer. -For examples: 1- keyboard: used to input the words and the numbers and contains standard typewriter keys and specialized keys (F1,F2,…). 2-mouse : small hand-held device, as it moved, a rolling ball on the underside transmits information to the computer which move he cursor. -The cursor : is the symbol on the screen that show where the data may be entered next. -The mouse has two or three buttons to perform the actions by press on them.

5. 5 3- trackball : it is a mouse turned upside down. The user rotate the ball with the fingers to move the cursor on the screen, and it saves the space which is taken by the mouse 4- touch pad: it is touch – sensitive device. We can move the cursor by move the finger on the pad surface (used in laptops).

6. 6 6- light pen : it is alight – sensitive device, or pen-like device, connected to the computer by wire and. -The user can bring the pen to any point on the display screen and press the pen button to identify the location to the computer. -the light pen can read the bar codes. 7- Scanners: the scanners can convert page contents text, image, pictures, graphics into electronic signals, that the computer can handle and store it. - the Scanners can read the bar codes.

7. 7 -Optical character recognition (OCR): is a system which decode scanned input into binary format that the computer understand, edit, compute, process. -8- Joystick : is a small hand-lever that can be moved in any direction to controls movement on the screen and use some button to perform some actions (used in games). 9- microphone : used o record the sound on the computer or input spoken text into the word processor.

8. 8 11- Digital camera : the same as traditional camera but use the flash or disk to store images. 12- video camera: connected to the computer to be used in video conferencing or store movies. 13. Touch Screen: it is a video display screen that has been sensitized to receive input from the touch finger

9. 9 Output devices Allow you to output information from the computer. 1- video display units (VDU) (monitors): display the work being done by the cpu, display the result of the processing, display texts, graphics, images, forms and so on. Types of monitors: 1- cathode ray tube (CRT): it is a vacuum tube used as display screen in computer or video, used in desktop computers and televisions. 2- flat-panel display: it is a thin screen that uses the different technologies to reduce the size and weight such liquid crystal display (LCD), plasma displays.

10. 10 Characteristics of monitors: #- colors: depend on the type of the screen and the graphic adapter. #- size: is the diagonal of the screen ( 15,17,19,21,…). #- resolution: the number of dots (pixels) that can displayed on the screen, high resolution means better quality.

11. 11 3- printers: used to print the soft copy (data) to hard copy on papers. Types of printers: i.-daisy wheel : characters are raised on the wheel, which strike the ribbon placed between them and the paper. (noisy and slow and produce carbon copies) ii.Dot matrix : use the pins to strike on an inked ribbon against paper. (inexpensive, produce carbon copies)

12. 12 iii.Inkjet : spray one more colors of small droplets of ink at high speed onto paper. and its running cost is high. (carbon copies can’t be produced). (use one color or multiple colors) iv.Laser printer: use a laser beam source to create a dot-like images on a drum. And these image treated magnetically charged ink-like and transferred from drum to paper. (high quality, used for heavy use, expensive, can’t produce carbon copies)

13. 13 4. Plotters: use pen to draw on the paper under the computer control and the mapping software (used to draw maps). 5. Speakers: used multimedia to produce sounds. 6. Speech synthesizer(المنسقات الصوتية): it is software that produce resembles human speech. 8. Projectors: device that connect to computer to display output to large board. 9. Touch Screen it is a video display screen that has been sensitized to receive input from the touch finger.