The document provides an overview of computers, including their history, components, types, and uses. It describes how computers store and process data to produce information. Key components include the central processing unit (CPU), which contains the arithmetic logic unit (ALU) and control unit (CU). The document also discusses different types of computer memory, including random access memory (RAM), read only memory (ROM), cache memory, and various storage devices like floppy disks, hard disks, CD-ROMs, and DVDs.

2. By Mrs. Niti Arora Introduction to Computer Let's Explore and Learn

3. Index Computer Overview Computer Memory Input Devices Output Devices Exit

4. Computer System : An Overview

5. “ Information is power and Computers are amplifiers of information” Quote to Remember

6. Computer is an electronic device that stores, retrieves, and processes data, and can be programmed with instructions. A computer is composed of hardware and software, and can exist in a variety of sizes and configurations. What is Computer?

7. Computer has evolved an information technology era which refers to the Creation, Gathering, Processing, Storage, Presentation and Dissemination of information.

8. COMPUTER AND INFORMATION Information is a powerful tool and is the driving force behind every economy. In today’s world , Information is multiplying at a manifold speed, and to manage it we need the help of a magic machine - The Computer.

9. SPEED It has an ability to perform at a high speed. The human equivalent of an average computer would be more than one million mathematicians working 24 hours a day. ACCURACY Computers are very accurate. If the input and the instructions are accurate the output will also be accurate. RELIABILTY Computer are immune to tiredness and boredom or fatigue. They are more reliable than human being. Characteristcs of Computer

10. HIGH STORAGE CAPACITY Computer has a very large memory to store data. DILIGENT Unlike humans Computer does not get bored or tired. Hence can work for long hours. VERSATILITY Computer can perform various jobs efficiently. It can work in various areas.

11. Weakness of computer HIGH STORAGE CAPACITY Computer has a very large memory to store data. DILIGENT Unlike humans Computer does not get bored or tired. Hence can work for long hours. VERSATILITY Computer cn perform various jobs efficiently. It can work in various areas.

12. Where all this magic machine can be used ? Field Of Education Computers are used as a teaching aid and as a research tool. Medical field Railways and Airways ticket reservation.

13. Banking and accounts Communications - E-mail, Video conferencing banking and brokerage etc. Weather forecast Space research Design and research work

14. Law enforcement by Police Government Military Music Theatre, film And Television Computer at Home

15. This Is How A Computer Looks Like!

16. Some Historical Facts . The first home personal computer was not sold until 1977 . We have come a long way since then. Did you know that in 1983 there were approximately 2 million personal computers in use in the United States alone. However just 10 years later in 1993 the number had jumped to more than 90 million .

17. Inside View of the Computer Floppy Drive RAM ROM SPEAKER HARD DISK DRIVE

18. How A Computer Works! INPUT PROCESSING DATA OUTPUT INFORMATION We feed the Data through Input unit (Keyboard) Computer Processes (Works on) the data in the Processing unit - CPU Computer gives the information (Result)

19. Important Terminologies Data - Unprocessed raw facts and figures are known as DATA. Information - processed data which conveys proper meaning is known as INFORMATION. Personal Computer - A compact machine which can be placed on a table used for daily day-today work used in offices, school etc. is called PERSONAL COMPUTER.

20. Types of computer Embedded Computer . Computer which exist in various size used in various appliances. Programmable Computer . Computer which comes in various sizes, speed etc. Laptop & Desktop . Computer used in home and business etc. Workstation . Computer used for connecting other computer in a computer network. Main frames . Computer used for sharing ,controlling inter connected computer. Super computer . Computer used in complex time consuming calculation

21. Central Processing Unit- The Brain The Central Processing Unit(CPU) of a computer is responsible for carrying out the processing job with aid of memory. The CPU is the brain of computer. Components of CPU:- Arithmetic Logic Unit(ALU) Control UNIT(CU) Memory

22. Arithmetic Logic Unit(ALU) The ALU is responsible for carrying out arithmetic operations such as addition and subtraction as well as logical decisions such as whether one number is bigger than another. All programs consist of complex sets of arithmetic and logical operations. Another way of thinking of a logical operation is as a decision making operation.

23. Control Unit(CU) The control unit is responsible for loading and interpreting the individual instructions that comprise the computer program. These instructions are in a language called machine code . Machine code is a pattern of ones and zeros. The control unit also has the task of getting the data needed by the instructions and returning the results of the processing after the instruction has been executed.

24. Memory Because the CPU can perform its operations much faster than data can be transferred from RAM, many CPUs have on-board cache memory. This is memory that the control unit can access very quickly and use for intermediate storage. Further, data and instructions can be loaded into cache before they are actually needed. When they are needed, the transfer is much faster than it would have been if RAM had been used.

25. Click here for block diagram BACK

26. Computer Memory

27. Concept of Memory Let’s understand what is Computer’s memory ... It is an electronic holding place for the instructions and the data that the microprocessor of the computer can reach quickly. Like the Grey cells in our brain, the computer memory consists of binary cells to store the information.

28. C omputer memory is measured in bytes. A single byte is made up of a series of 1's and 0's normally traveling in pairs of eight. These eight 0's and 1's are the way the computer communicates and stores information. With each keystroke or character a byte of memory is used. In another article you will learn more about bits and how the computer thinks.

29. Measuring Memory Measuring Memory Term/Byte Abbreviation Value Kilo K, KB 1,024 bytes Mega M, MB, Meg 1,048,576 bytes (Million) Giga G, GB, Giga 1,073,741,824 bytes (Billion) Tera T, TB, Tera 1,099,511,628,000 bytes (Trillion)

30. Here is another way of looking at the measurement of memory: Measuring Bytes 8 bits = 1 byte 1000 bytes = 1 kilobyte 1000 kilobytes = 1 megabyte 1000 megabytes = 1 gigabyte 1000 gigabytes = 1 terabyte

31. Types of Memory

32. Primary Memory Primary memory is the memory that is intimately associated with the actual working of the computer. This includes memory that holds the start-up routines as well as the current program and data it is working with. There are various forms of primary memory: RAM, ROM and Cache memory. It is the main or internal memory .

33. It can be broadly categorized into two parts RAM (Random Access Memory) ROM (Read Only Memory) Cache Primary Memory

34. RAM It is known as the Read and Write memory .This memory is volatile. Whatever information you store is temporary in nature and when you switch off the computer everything is erased.

35. ROM It is a memory unit that performs the Read operation only and does not have a write capability . The Binary information in the ROM is made permanent during the hardware production of the unit and it is not accessible to users to store information.

36. The following table compares RAM and ROM . RAM ROM Function Store the currently active programs and their data. Stores certain fixed routines such as the boot-up routines. Volatility RAM is volatile: When the computer is switched off, the contents are lost. ROM is non-volatile: When the computer is switched off, the contents are not lost. Changeable The contents of RAM can be changed or deleted. The contents of ROM cannot be changed or deleted.

37. CACHE MEMORY Other types of temporary memory are cache (pronounced "cash") and virtual memory. Both of these types of memory supplement the computer's primary RAM and perform the same function as RAM.

38. Secondary Memory It is the Permanent memory. The information stored is permanent in nature and it uses external storage devices like Floppy disk, Magnetic disk, CD-ROM etc. In human terms Primary memory is the memory inside our brain and Secondary memory are the notes copy we maintain to store the information.

39. Floppy Disk We used it to store information and it’s main advantage is that it is transportable because of its size. A diskette comprises a plastic flexible disk enclosed inside a tough plastic cover. At one end is a window. When the diskette is placed inside a diskette drive, the window is pushed to the side. The read-record head inside the drive makes contact with the magnetic disk.

40. Hard Disk A number of floppy disk put together in a box and kept in the CPU to store and retrieve information is a Hard Disk . It consists of a number of rotating platters which are covered with a magnetic film. Information is stored using the magnetic properties of the film. The platters rotate from between 5000 and 8000 rpm or faster.

41. CD - ROM A CD ROM uses optical technology. When data is written, small pits are burned into the surface using a highly focussed laser beam. These are read by another laser beam. CD-ROM is prepared and read using Laser Beam . It has a large storage Capacity and is being widely used now for archival storage .

42. The Digital Versatile Disk is a development of the storage technology of the CD ROM. Using newer storage methods and higher quality media, a DVD can store about 4 Gb of data. This is enough to store a full length film. DVD

43. A zip disk is a removable magnetic disk which fits into a special zip drive. The surface is coated with a special scratch resistant material which makes a zip disk a very robust storage device. It comes in a number of capacities: 100, 250 and 750 Mb. The speed of a zip drive is faster than all but the very fastest of CD drives. Its robustness and speed make it an excellent backup device. However, its capacity is much less than that of hard drives and tape drives which limits its use for very large amounts of data. ZIP DRIVE

44. When you think USB flash drive, think USB Drive. This portable storage products let you store, transfer and carry your data securely anywhere. Pocket-sized and lightweight, USB Drives can store your music, images or computer files in a snap. USB FLASH DRIVE

45. A new type of external memory is the flash disk or memory stick. This is a solid state device (no moving parts) that connects to the computer via the USB port. It provides a very fast and reliable method of storing data externally. They are at the moment fairly expensive, especially the larger capacity devices. They tend to be limited to a maximum of about 2 Gb. This figure can be expected to increase quite dramatically over time. Flash Memory & Memory sticks BACK

46. INPUT Devices

47. Basic Computer Operation A computer performs basically five major operations or functions. These are: 1) It accepts data or instructions by way of input. 2) It stores data by way of storage devices. 3) It can process data as required by the user. 4) It gives results in the form of output. 5) It controls all operations inside a computer .

48. Input Device Input is the process of entering data and programs into the computer system. The input unit is formed by the input device attached to the computer. The input device takes data from user to the computer in an organized manner for processing. Example of input device: - Keyboard Mouse Scanner

49. Keyboard This is the standard input device attached to all computers. The layout of keyboard is just like the traditional type-writer with some extra command key and functions keys. It contains a total of 101-104 keys. The computer can recognize the electric signals corresponding to the correct key combination and processing is done accordingly.

50. Let’s see how a keyboard takes the input.

51. Functioning of a keyboard When you press the K key on the keyboard, a plunger attached to the key pushes against the spring or rubber dome. The pressure from your finger overpower the resistance of the springs or dome so that it collapses. This causes two electrical contacts to come together and electricity flows through them making a circuit . When you lift your finger the spring or dome pop the key up and the circuit is broken.

52. Mouse The mouse is an input device also known as pointing device with a roller on its base. When a mouse rolls on a flat surface the cursor on the screen moves in any direction giving easier and faster movement.

53. Let’s see how a Mouse works.

54. Functioning of a mouse A mouse lets you to control the onscreen pointer to make menu selection and to manipulate graphics and text on your screen. This mouse has no feet instead a small ball sticks through its underside housing. When you move the mouse the ball moves too. As the ball turns it rubs against two roller and they also turn. One roller senses when mouse moves side-by-side. The other roller senses up-n-down movement. Together the two roller can tell which direction you moved the mouse.

55. Scanner Scanner is an optical device that can input any graphical matter and display it back. The main advantage of direct entry of information is that the user doesn’t have to key the information.

56. A touchpad is a device that senses pressure to guide the pointer on the computer screen. It is generally a small square area below the keyboard. As the user moves his/her finger across the touchpad, the pointer moves on the screen. Next to the pad are two buttons used for clicking in exactly the same way as those on a mouse. TOUCH PAD

57. A trackball acts as a type of overturned mouse. The ball is on the top side of the object. By rolling the ball you can move the pointer across the screen. Some keyboards have an in-built trackball. The trackball has been superseded by the touchpad. TRACK BALL

58. A light pen is a device which is sensitive to variations in patterns on a surface. Light pens act like a miniature scanner and can read text as they are dragged across the printed page. This can be transferred directly to the current open document. LIGHT PEN

59. A bar code is a pattern of vertical lines in which the spacing and thickness can be used to represent data. A bar code reader is a device that can read and interpret bar codes and input the data into the computer. BARCODE READER

60. A joystick is a device that is familiar for use in games to move objects on the screen. However, it is also used to control the movements in computerised industrial machines such as lathes. It consists of a small vertical lever which can move in any direction. These movements are translated to the computer which in turn uses them to control the movements of machinery. JOYSTICK

61. Instead of film, a digital camera uses a light sensitive screen at the back of the camera. A small computer inside the camera converts the pattern on the screen into a standard graphics file which can then be transferred to a computer. DIGITAL CAMERA

62. A microphone translates speech into an electronic signal. Modern speech recognition software is able to translate this into either commands or data. This enables the user to use a microphone as an alternative to the keyboard. MICROPHONE

63. M agnetic I nk C haracter R ecognition is a character recognition system that uses special ink and characters. When a document that contains this ink needs to be read, it passes through a machine, which magnetizes the ink and then translates the magnetic information into characters. MICR technology is used by banks. Numbers and characters found on the bottom of checks (usually containing the check number, sort number, and account number) are printed using Magnetic Ink. To print Magnetic Ink need, you need a laser printer that accepts MICR toner. MICR provides a secure, high-speed method of scanning and processing information. MICR

64. Optical character recognition , usually abbreviated to OCR , is computer software designed to translate images of handwritten or typewritten text (usually captured by a scanner ) into machine-editable text, or to translate pictures of characters into a standard encoding scheme representing them (e.g. ASCII or Unicode ). OCR began as a field of research in pattern recognition , artificial intelligence and machine vision . Though academic research in the field continues, the focus on OCR has shifted to implementation of proven techniques. OCR BACK

65. Output Devices

66. Output Devices Output is the process of producing results from the raw data for getting useful information. Mainly there are two principal devices to output information from a computer. These are: Monitor Printer

67. Monitor / Visual Display Unit The most popular output device is visual device unit. A keyboard is used to input data and monitor is used to display the input data and to receive messages from the computer. A monitor has its own box which is separated from the main computer system and is connected to the computer by cable. In some system it is compact with the system unit. It can be colored or monochrome.

68. Let’s see how monitor functions.

69. How monitor works Signals from computer’s video card are loaded into three electron guns at the base of the monitor. There is one gun for each of three color Red, Blue and Green. These three colors when mix together can create all the colors you see on your screen. Now these gun don’t shoot bullets instead they shoot powerful beams of electrons toward the face of the monitor. The beam pass through a deflection unit. It uses the magnetism to bend the electronic beam So that they can sweep across the entire screen and create the picture we see.

70. Printer Printer is an important output device which can be used to get a hard copy or printed copy of the processed data or result on paper. There are different types of printer that are designed for different types of application. Printers are classified as Impact Non-Impact printer

71. Impact Printer Impact printers use the familiar type-writer approach of hammering a typeface against the paper and inked ribbon. E.g.. DOT MATRIX

72. Non-Impact Printer Non-Impact printer do not impact or hit a ribbon to paper. They use electrostatic chemical and inkjet technologies. These can produce color printing and elaborate graphics. E.g. Laser printer Inkjet printer

73. A plotter consists of a device that can move paper both backwards and forwards. On the top of the device one or more pens are able to move horizontally across the paper. The combined movement of the pens horizontally across the paper and the vertical movement of the paper allows complex continuous diagrams to be drawn. PLOTTER

74. Some plotters allow different colour pens to be used to create diagrams in multiple colours. In other types of plotters, the paper lies on a flat bed. The mechanics of the plotter are so designed that the pens can move both across and down the paper to create the diagram.

75. Modern computers using the appropriate software can turn text in a document into audible speech. This is known as speech synthesis . Other types of software allow music and other sounds to be created and played back. The sound is transmitted through a speaker in the same way it is in a sound system or radio. SPEAKER

76. INPUT/OUTPUT DEVICES Some devices function as both input and output devices. A touchscreen is a special type of screen in which the screen not only displays output but also responds to being touched. A typical example is their use in autotellers at banks. Part of the screen contains information. Other parts may contain a menu. When you touch one of the icons on the screen, the system responds to the associated command. BACK