2. Lesson - 1 What is a PC? Components of a PC Main Unit CPU Memory
Keyboard
Peripherals

3. What is a Computer?
A computer is an electronic device, operating under the control of instructions (software) stored in its own memory unit, that can accept data (input), manipulate data (process), and produce information (output) from the processing. Generally, the term is used to describe a collection of devices that function together as a system

4. Computer systems have four parts
Hardware
Software
Data
User

5. What Does A Computer Do?
Computers can perform four general operations, which comprise the information processing cycle.
Input
Process
Output
Storage

6. Computers use the same basic hardware
Hardware categorized into four types

7. Four parts Processing Devices Memory Devices Input and Output Devices
Storage Devices

8. What Are The Primary Components Of A Computer ?
Input devices.
Central Processing Unit
Memory.
Output devices.
Storage devices.

9. Structure of a Computer System (Information Processing Cycle)
CPU
Input
Output
RAM
Auxiliary
Storage

10. Data and Information
All computer processing requires data, which is a collection of raw facts, figures and symbols, such as numbers, words, images, video and sound, given to the computer during the input phase.
Computers manipulate data to create information. Information is data that is organized, meaningful, and useful.
During the output Phase, the information that has been created is put into some form, such as a printed report.
The information can also be put in computer storage for future use.

11. Input Devices Keyboard Mouse or Trackball Joystick Touch Screen
Light Pen
Image Scanner
Digital Camera
Voice Input

12. KEYBOARD The Keyboard is an input device. Older Keyboards were 84-keys
Common keyboards are 102-keys
Multimedia supported keyboards 109-keys

13. Keyboard Normally consists of Four main parts.
1.Typewriter or Alphanumeric Keys
(because it has the alphabet and numbers.)
2. Arrow keys or Cursor keys
(pointing up, down, left and right move the cursor)
3. Numeric keypad or Num keypad
(Numbers 0 to 9, decimal point, num lock)
4. Function Keys
F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11 and F12.

14. Mouse A mouse is also an input device.
A mouse usually has two or three finer buttons that you can press: One on the left, one on the right and (sometimes) one on the centre
In Windows applications, clicking the left mouse button will make your computer do something, like opening a folder or starting a program. Often you will need a double click. Clicking on the right mouse button will provide you with information and/or a menu of operations that you can choose from.

15. (CPU) Central Processing Unit
The central processing unit (CPU) contains electronic circuits that cause processing to occur. The CPU interprets instructions to the computer, performs the logical and arithmetic processing operations, and causes the input and output operations to occur. It is considered the “brain” of the computer.

16. Structure of CPU Memory Arithmetic and (Registers) Logic Unit
Control Unit

17. Output Devices
Monitor
Speaker
Printer
Plotter

18. Monitors Cathode Ray Tube (CRT) Most common type of monitor
Electrons fired from the back
Electrons excite phosphor to glow
Phosphor is arranged in dots called pixels
Dot mask ensures proper pixel is lit

19. CRT drawbacks
Very large
Very heavy
Use a lot of electricity

20. Monitors Liquid Crystal Display (LCD) Commonly found on laptops
Desktop versions exist
Solve the problems of CRT
Fluorescent lights provide illumination

21. Storage Devices Volatile Memory (RAM) Non-Volatile Memory ROM
Hard Disks
Floppy Disks
Compact Discs – CD and DVD drives

22. Volatile Memory
Memory also called Random Access Memory or RAM (temporary memory) is the main memory of the computer. It consists of electronic components that store data including numbers, letters of the alphabet, graphics and sound. Any information stored in RAM is lost when the computer is turned off.

23. Non-Volatile Memory
Read Only Memory or ROM is memory that is etched on a chip that has start-up directions for your computer. It is permanent memory
The contents of ROM remain when power is switched off.

24. Floppy Disks
Auxiliary storage devices are used for permanent storage of data
A floppy disk is a portable, inexpensive storage medium that consists of a thin, circular, flexible plastic disk with a magnetic coating enclosed in a square-shaped plastic shell

25. Hard Disks
Another form of auxiliary storage is a hard disk. A hard disk consists of one or more rigid metal plates coated with a metal oxide material that allows data to be magnetically recorded on the surface of the platters

26. Compact Discs
A compact disk (CD), also called an optical disc, is a flat round, portable storage medium that is usually 4.75 inch in diameter.
CD-ROM (read only memory),
CD-RW – (rewritable)
DVD-ROM
DVD+RW

27. Hardware vs. Software
Hardware - the physical parts that make up the computer
e.g. CPU, memory, disks, CD-ROM drives, printer.
Software - computer programs and applications.
Operating system, word processor, games, etc

28. Software A computer program or software tells it exactly what to do.
A computer program is a set of instructions to the computer.
Computer software is the key to productive use of computers. Software can be categorized into two types:
System software
Application software.

29. Application Software
Application Software consists of programs that tell a computer how to produce information. Some of the more commonly used packages are:
Word processing
Electronic spreadsheet
Database
Presentation graphics

30. System Software
The most important system software is the operating system.
Examples of operating systems:
Windows, DOS, Apple, UNIX

31. Purpose of an Operating System?
An OS is a computer program that:
Provides the interface between you and your computer
Controls the hardware of the computer.
Run your computer applications or programs
Communicate with your network

32. Classification of Computers or Types of Computer
Computers can be classified into three ways:
According to Function
According to Size and Capacity
According to Purpose

33. According to Function
According to function computers can be classified into three types, namely:
Analogue Computers
Digital Computers
Hybrid Computers

34. Analogue Computers
Usually all the measuring devices are called Analogue computers.
An analogue computing devices can measure only the continuously variable quantities, such as Temperature, Pressure, Voltage, sound etc.

35. Digital Computers
Digital computers are high speed, programmable electronic devices that performs mathematical calculations, compare values and store the results. They recognize data by counting discrete signals. Representing either a high (on) or low (off) voltage state of electricity.
Working on Binary values (0) and (1)

36. Hybrid Computers
In special situations digital and analogue computers have been combined to create hybrid computers. The capacity of hybrid computers is most significant where the digital processing of data collected in Analogue form is desirable.
Petrol pump machines and speedometers are some example of hybrid computers.

37. According to Size and Capacity
Lap Top / Notebook, Palm Top
Micro Computers
Mini Computers
Macro Computers (Main Frames)
Super Computers

38. Lap Top / Notebook, Palm Top
These are the smallest computers in size
Look like office briefcase geometry box
They are termed as portable computers
These are very popular in use because of small size and less weight.

39. Tablet computers Newest development in portable computers
Input is through a pen
Run specialized versions of office products

40. Micro Computers Micro computers are small machines
These are low in price
It is cheaper, so there is no difficulty to maintain
Small business application can run on it
Home computed work can be performed
It is also called PC personal computer

41. Computers at home Many homes have multiple computers
Most American homes have Internet
Computers are used for
Business
Entertainment
Communication
Education

42. Mini Computers Called midrange computers
Power between mainframe and desktop
Handle hundreds of users
Used in smaller organizations
Very popular for time sharing system
These computers are used in laboratories for all types of engineering and scientific work.

43. Macro Computers (Main Frames)
They are large in size
Also called main frame computers
Used for networking as a main server
Main frame computers supports thousands of users
Used in world wide Airline Reservation system
They are used for a high amount of data processing and used as centralized data machine (e.g. Citibank credit card machine)

44. Super Computer These are very large in size
Use for complex scientific calculations
Its capabilities are much more than main frames
Very costly
Super computer supports small no of users
These are used in Nuclear physics, weather forecast and satellite controlling

45. Supercomputers The most powerful computers made
Handle large and complex calculations
Process trillions of operations per second
Found in research organizations

46. According to Purpose
General Purpose
Special Purpose

47. General Purpose computers
These computers are designed to perform various tasks and can be used for different calculations of data, for example personal computers can perform different tasks of work. It can compute data it can solve different problems, it can play music, videos etc…

48. Special Purpose computers
These types of computers can do only predefined work and is useless for any other kind of work. For example Visa card Machine can only insert Visa cards and can verify them. It cannot calculate any data.

49. THANK YOU