What is a computer?

1. What is a computer? Monitor A computer is an electronic machine that accepts information (Data), processes it according to specific instructions, and provides the results as new information. Floppy Disk Drive System Unit CD-ROM / DVD-ROM Drive Keyboard Mouse

2. Chapter:o1 Computer overview => Computer: A computer is an electronic device that can perform a different types of operations in accordance with set of instructions is called program. => Data: Data are raw facts. =>Information: Information is meaningful data.

4. INPUT UNIT CENTRAL PROCESSING UNIT OUTPUT => Input-Process-Output(IPO Cycle) : Certain input is needed to accomplished a task , a process is carried out on the input to obtain the output. Functional Components of a computer: In IPO Cycle, First stage is performed in computer by input unit, Second stage is performed by its central processing unit and the Third stage is performed by output unit. The main memory holds the input and intermediate output during the processing. MAIN MEMORY

5. =>INPUT UNIT: The input unit is performed by the input devices attached to the computer. Input unit is responsible for taking input and converting it into computer understandable form(the binary code). EXAMPLES:KEYBOARD,MOUSE MICR, OMR, OCR, JOYSTICK. => Central Processing Unit: The CPU is the control Centre for a computer .it guides , directs, governs, its performance. It is brain of computer.

6. => The CPU divided into two parts: (a).Arithmetic Logic UNIT(ALU): The ALU performs all four arithmetical (+, -,*,/)and some logical operations(<, >,<=,>=,<>). (B) CONTROL UNIT(CU): The CU control and guides the interpretation , flow and manipulation of all data and information. The CU sends control signals until the required operation are done properly by ALU and memory. It also responsible for execute the program. The CU gets program instruction from memory and executes the one after the other. After getting the instructions from memory in CU, the instruction is decoded and interpreted.

7. =>OUTPUT UNIT: The output unit is performed by the output devices attached to the computer. the output coming from CPU is in the form of electrical binary signals which needs conversion in some form which can be easily understood by human beings i.e. characters, graphical or audio visual. Examples: Monitor, printer , plotter, speaker. => MEMORY: The memory is a device which can store the data and information. => MEMORY CELL: It is a device which can store a symbol selected from set of symbols. bit cell 0 cell 1

8. => BYTE OR NIBBLE: A group of 8 bits is called byte and a group of 4 bits is know as nibble.

9. => There are two types of memory (a). Primary (Main ) Memory: It is also know as temporary Memory. Ram and Rom (b). Secondary Memory: To store the data and information permanently. CD, Hard disk. => Hardware : The physical and tangible parts of the computer. i.e. The components that can seen and touched. Monitor ,mouse etc. => peripherals: The peripherals are devices that surround the system unit. Examples: keyboard, mouse, speaker, printer, monitor. =>Software: The set of program that govern the operation of a computer system.

10. Types of Software There are two types of software 1.System software 2. Application Software System software: The software that controls internal computer operations is called system software system software Divided into two parts Operating system Language system.

11. Operating system(os): An operating system is a program which acts as an interface between a user and the hardware(i.e. all computer resources) Functions of operating system: (i).It provide the instructions to prepare user interface.i.e, way to interact with user whether through typed commands or through graphical symbols. (ii). Loads necessary programs (into the computer memory) which are required for proper compute functioning. (iii). Coordinates how programs work with the CPU , keyboard, Mouse, Printer, and other Hardware as well as with other software (iv). Manages way information is stored on and retrieved from disks

12. A set of software instructions that tells the computer what to do is called a computer program. • Major Component of Computer System are:

13. TYPES OF OS: 1.Single Program OS. As the name suggests , this OS is single user operating system , so only one user program can be supported and executed by it at any point. 2.MultiProgram OS. It supports multiprogramming.i.e., more than one user can be supported by it, therefore ,more than one user programs are loaded and active in the main store at he same time. 3.Time Sharing OS.This OS uses the time sharing technique. Each active user program is given a fair share of CPU time(δ),if the time elapses or an I/O operation is requested, CPU shifts over to the next jobs waiting and the previous program. 4.Real Time os: The jobs have fixed deadlines and the jobs have to be completed within their deadlines. the system performance is measured by its ability to complete its jobs within specified deadlines. If a job cannot be complete within its deadline, its situation is called deadline overrun. 5. Multiprocessing os: The Multiprocessing os is capable of handling more than one processors as the have to be executed on more than one processor(CPU)

14. Examples of operating systems are: Unix, Windows NT, Windows XP, MS-DOS, Linux, Solaris, VMS, OS/2 and System =>Language processors: It is a collection of program that convert high level language program into machine level language program. High-level language: A high-level language consists of instructions, or statements, that are closer to English and common mathematical notation. When programming in a high-level language, you do not have to concern yourself with the specific machine language of the CPU. Assembler: It translates(converts) the assembly language program into an equivalent machine language program. .

15. Interpreter: IT Converts a High level Language program into machine language by converting and executing it line by line. if there is any error in any line, it reports it at the same time and program execution cannot resume until the error is rectified. Once a given instruction has been executed, then it translates and executes the next, and so on. Compiler: It Translate(convert) the Entire HLL program into machine language program in one go, and reports all errors of the program along with the line numbers. All instructions are compiled before any are executed by the CPU.

16. Application Software: It is a set of programs necessary to carry out operations for a specified application. => Application software Categories into two types: (a). Customized Application software : This type of software is tailor –made software according to a user’s requirements. The software is developed to meet all the requirements specified by the user. (b). General Application software : This type of software is developed keeping in mind the general requirements for carrying out specific task

17. Strength and Weakness of a computer: => Computer Strengths: (i). Speed: Computer are much faster as compared to human beings. A computer can perform a task in a minute that may take day if performed manually. (ii). High storage Capacity: Computers can store a large amount of information in very small space. (iii). Accuracy: Computer s can perform all tha calculations and comparisons accurately provided the hardware does not malfunction. (iv). Reliability: Computers can immune(protect) to tiredness and boredom or fatigue(mental exhaustion) . (v). Versatility: Computers can perform repetitive jobs efficiently. They even can work in the area where human brain can err.

18. Computer Weakness: (i). Lack of Decision Making Power: Computer cannot decide on their own. (ii). IQ Zero: Computers are dumb machines with zero IQ => FIRMWARE: It is prewritten program that is permanently stored in read only memory (ROM). It configures the computer and not easily modifiable by the user. Example: BIOS(BASIC INPUT OUTPUT SERVICE) => Liveware: The people associated with and benefited from the computer system.

19. Classification of Computers of On the basis of How It Functions • The current classifications of computers place them into Three categories: • Analog Computer • Digital Computer • Hybrid Computers

20. Classification of Computers of On the basis of How It Functions Digital Computers • Operate on continuous data, like measuring temp. changes • Faster • Accuracy of an analog computer is restricted to the accuracy with which physical quantities can be sensed and displayed. • Specific Purpose computers Analog Computers Digital Computers • Digital computers work on discrete data. • digital computer can process data with greater accuracy • We generally use digital computers for business and scientific data processing.

21. Hybrid Computers • Hybrid computers are computers that comprise features of analog computers and digitalcomputers. • The digital component normally serves as the controller and provides logical operations, while the analog component normally serves as a solver of differential equations.

22. Digital Computer classified into two types • (i). Purpose –wise • (ii). Size and Performance wise • (i). Purpose –wise digital computer are classified into two types. • (a). Special-purpose computer: It is designed to performed a specific task. the instructions to carry out the task are permanently stored in the machine. • (b). General-purpose computer: it can work on different types of programs input to it and be used in countless applications. The program are not permanently stored .

23. Size and Speed Based Classification of digital Computer Systems • The current classifications of computers place them into five categories: • Embedded computer, • ,Microcomputers (Personal Computers)  • Minicomputers, • Mainframes, • Super Computers,

24. => Embedded computers: These computers are typically preprogrammed for a specific task, such as tuning to a particular television frequency. Examples: television, washing machine.etc.

25. PERSONAL COMPUTER • The term microcomputer, also known as personal computer (PC), or a computer that depends on a microprocessor. A microcomputer contains a central processing unit (CPU) on a microchip (the microprocessor), a memory system (read-only memory and random access memory), placed on a motherboard.Example:  desktop, notebook, laptop, handheld devices.Charcteristics: • developed in 1980 •  designed for single user •  not very powerful or expensive •  found in homes

26. Micro computer also divided into three types • PDA(Personal digital assistants) • Laptops and desktop personal computer. • Workstations: • Between minicomputer and microcomputer- in terms of processing power. • Looks like PC and used by one person.

27. MINICOMPUTER • Another term rarely used anymore, minicomputers fall in between microcomputers (PCs) and mainframes (enterprise servers). • Minicomputers are normally referred to as mid-range servers now. • Characteristics: •       Smaller than mainframe •       Can do several jobs at once •       Can be used by many people at one time •       Used by small companies

28. MAINFRAME • In the early days of computing, mainframes were huge computers that could fill an entire room or even a whole floor. • As the size of computers has decreased while the power has increased, the term mainframe has fallen out of use in favor of enterprise server. You'll still hear the term used, particularly in large companies to describe the huge machines processing millions of transactions every day.   • Characteristics:  •      Expensive •      Powerful and fast •      Is not limited to one job •      Used by business and small government • organizations • The main difference between a supercomputer and a mainframe is that a supercomputer channels all its power into executing a few programs as fast as possible, whereas a mainframe uses its power to execute many programs simultaneously.

29. SUPER COMPUTER • The fastest type of computer. • Supercomputers are very expensive and are employed for specialized applications that require immense amounts of mathematical calculations. • For example, weather forecasting requires a supercomputer. • Other uses of supercomputers include animated graphics, , nuclear energy research, and petroleum exploration. • Characteristics • Powerful •    Expensive •    Dedicated to one purpose - weather, satellites, military •    Used by large governments or very large companies •    Can be used by thousands of people at the same time •    Very large - fill rooms

30. Sixteen racks of IBM's Blue Gene/L supercomputer can perform 70.7 trillion calculations per second, making it the fastest machine known so far.

31. =>Input Device:A device used to provide data and instruction to the computer are called input device. Example: keyboard 1.Keyboard:It is used to enter both numerical and characters type data. it is like a mechanical typewriter with alphanumeric and special keys.

32. =>Types of Keyboard There are two type of keyboard 1.Serial keyboard 2.Parallel keyboard =>A serial Keyboardis one which communicates the data to the central processing unit one bit a time. that is the bit pattern that forms a particular character is sent on a single wire.

33. A parallel Keyboardcarries one byte(8bits) at a time to the central processing unit. The bit pattern that forms a character is sent on 8 different wires. • Standard Keyboard Layout: • A standard computer keyboard has about 100 keys. • Most keyboards use the QWERTY layout, named for the first six keys in the top row of letters.

34. The Keyboard - Standard Keyboard Layout • Most keyboards have keys arranged in five groups: • 1. Alphanumeric keys • 2. Numeric keypad • 3. Function keys • 4. Modifier keys • 5. Cursor-movement keys

35. ACADEMIC RECORDS Password ENTER * * * * * Invalid Password

36. Ergonomic Keyboards • Long periods of keyboard use can cause injuries. • An ergonomically correct keyboard can help you avoid injuries. • You also can avoid injuries by adopting correct keyboarding practices.

37. Mouse: It is small hand held pointing device connected to CPU through a cable.

38. The Mouse - Mouse Techniques Using the mouse involves five techniques: • 1.Pointing; Move the mouse to move the on-screen pointer. • 2.Clicking; Press and release the left mouse button • once. • Double-clicking; Press and release the left mouse • button twice. • Dragging; Hold down the left mouse button as you • move the pointer. • Right-clicking; Press and release the right mouse button.

39. => Types of Mouse: There are three types of mouse. (i). Mechanical mouse: It has a rotating ball at bottom and has two click buttons on the top. As the mouse is moved across a rubber pad or a flat surface, the ball rolls and its movement is converted into electrical signal and communicated to CPU. these movements are interpreted and display on the screen as an arrow. (ii).Opto- Mechanical mouse: It is same as Mechanical mouse but an optoMechanical mouse: uses optical sensors to sense the motion of the ball

40. => Optical Mouse: optical mouse have an optical sensor in place of a mouse ball. The optical mouse now a day use a laser to detect the mouse’s movement. => Wireless Mouse: Wireless or cordless are not physically connected to the computer .it uses either infrared or radio wave to communicate with computer.

41. Light Pen:It is a pencil shaped device. it is used to select screen coordinates by detecting the light coming from illuminated points on the CRT(cathode RAY Tube) screen. when an activated light pen, comes in contact with an illuminated spot on the screen. it generates an electrical signal which is taken as input to the system. then computer responds to it by displaying more information about the pointed item. it is useful in graphics program

42. Touch Screens:A type of display screen that has a touch-sensitive transparent panel covering the screen is known as touch screen. • Graphics Tablet: A graphic(digitizing) tablet is input device that enables to enter drawings and sketches into a computer. It consists of an electronic surface and a censor.

43. Digital Camera: A Camera that stores images digitally rather than recording them on film is called Digital camera. Once a picture has been taken, it can be downloaded to a computer. • Smart Card:The smart card contains a microprocessor that retains certain security and personal data in its memory at all times. The special reader machine that can read information on smart cards are called smart-card readers. It can hold more information, have some processing capability and are almost impossible to duplicate.

44. Joystick:It consists of a small rod(level or stick) mounted on a rolling ball. this rod is used to control the screen cursor. the movement of rod is converted into electric signals which are then sent to CPU for the subsequent processing. the CPU interprets these signals and displays the movement on the CRT screens.

45. Microphone(MIC): It is used to record sound. It convert sound waves into audio signals and vice versa. • Magnetic Ink Character Reader(MICR):Human readable characters are printed on documents(such as cheques) using a special magnetic ink. Special font has been set for these characters by American Banking Association.A magnetic ink character reader(MICR) reads these characters by examining their shapes ,using a 7*10 matrix.

46. Scanner:A Scanner is a device like photocopier, which creates an electronic form of printed image • The scanners can convert any image into electronic form by shining light on to the image and sensing the intensity of the reflection at every point.

47. Types of scanner • Hand-held Scanner: 1.Less Expensive 2.Less wide 3.More passes per scan 4.More handy • Flated Scanner: 1.More Expensive 2.Flat Surface 3.Single Pass per Scan 4.Higher Quality Image • Drum Scanner: 1.Medium Sized 2.Drum roles over Image for Scanning

48. Optical Character Reader(OCR):An optical Character reader is used to read character of special type font (or Fonts) printed on conventional paper with conventional ink. the printed characters are examined by passing them under a strong light and a lens system, which differentiates light (no ink) from inked areas, and a logical system which attempts to determine which of the possible characters is being examine.

49. Optical Mark Reader(OMR):Special Preprinted forms are designed with boxes which can be marked with a dark pencil or ink each box is distinctly so that the user clearly understands what response he is marking .such a document is read by a document reader,called optical mark reader. • objective • 1.question 2.survey 3.time sheet

50. Bar Code Readers:A Bar Code is a pattern of printed bars on various types of products. It emits a beam of light which reflects off the bar code image. A light sensitive detector in the bar code reader then identifies the bar image by recognizing special bars at the both ends of the image. once the bar code is identified ,the car pattern is converted into numeric code.