Computer Basics

1. Computer Basics CS-107 Introduction to Computing Aug-Dec,2010 Alak Roy Assistant Professor Dept. of CSE Royal Group of Institution Email : alakroy.nerist@gmail.com

2. What is 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) from the user, stores and process the given input to generate the output in the form of useful information to the user.

3. Data and Information DATA • Data 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. • All computer processing requires data. INFORMATION • meaningful, organized, and useful data is called information • Computers manipulate data to create information.

4. Why is a Computer so Powerful? • Perform information processing with amazing speed. • Reliable. • Accuracy. • Ability to store huge amounts of data & information. • Ability to communicate with other computers.

5. Components of Computer Systems • System Unit • Keyboard • Mouse • Monitor / Display • Printer

6. Devices that comprise a computer system Monitor (output) Speaker (output) System unit (processor, memory…) Printer (output) Storage devices (CD-RW, Floppy, Hard disk, zip,…) Mouse (input) Scanner (input) Keyboard (input)

7. Basic 2 Parts? • Hardware • Software

8. Software • Software is a part of the computer you cannot touch. Definition of Software: • Software is a set of instruction & computer programs and procedures that that help the computer in caring out their processing. • Necessary for proper functioning of computer. • Computer software is divided into two basic types: • System software • Application software

10. System software The program which are designed to control the different operations of the computer are known as system software. • Operating Systemis the base program on a computer is considered system software.  • It tells the computer how to work or operate. 

11. System software • Operating system software tells the computer how to perform the functions of loading, storing and executing an application and how to transfer data. • The operating system also allows you to load other programs that do specialized tasks on to your computer. (ex. Windows XP and Vista) • Microsoft Windows 98 is a widely used graphical operating system. DOS (Disk Operating System) is an older but still widely used operating system that is text-based.

12. Application Software • The program which are designed to perform a special task for the user are known as 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

13. Hardware • Definition of Hardware: • A group of electronics physical devices that make up a computer . Or • The computer and all equipment attached to it are called hardware. • The hardware is the part of the computer you can touch and see.

14. Hardware Parts • Input devices. • Processing devices or (Central Processing Unit) • Output devices. • Memory • Storage devices.

15. What does A Computer Do? • Computers can perform 5 general operations, which comprise the information processing cycle. • Inputting • Processing • Storing • Outputting • Controlling

16. External STORAGE unit Block diagram of Computer Magnetic Tape Magnetic disk INPUT Media Primary Memory Output Media Output Unit Input Unit Secondary memory Control MEMORY UNIT Data & Result Flow Arithmetic & Logic unit Control Unit Control instruction to units instruction to control units CPU UNIT

17. Input Unit • Accepts or read data & program to computer • Convert input information into suitable binary form acceptable to the computer • Supplies converted data & instruction to the computer system for further processing

18. Output Unit • It Convert machine readable information into human readable form. • Output unit / devices receive the processed data from the CPU and present it to the user in a desired form. • Act as an interface between computer and user • It supplies the converted result to outside world

19. Central processing Unit (CPU)or Processing Devices considered the “brain” of the computer. contains electronic circuits that cause processing to occur. Main Functions of CPU: CPU interprets instructions to the computer, CPU execute program, CPU performs the logical and arithmetic processing operations, and CPU Controls operations of all other components such as input/output devices. CPU causes the input and output operations to occur.

20. CPU Consist of: • Arithmetic & Logic Unit (ALU) • Performs arithmetic & logic operations (+,-,*,/,or,not,xor, etc..) • Control Unit (CU) • Control & coordinates the activities of all other units (ALU,Memory,i/o) • CU gets instruction out of memory unit & decode instructions. • Buses • Address Bus • Data Bus • Control Bus • Clock

21. CPU Consist of: C • Registers (CPU contains special purpose, temporary storage unit) • Program Counter (PC): to keep track of next instruction to be executed. • Instruction Register (IR): to hold instruction to be decoded by the control unit. • Memory Address Register (MAR): to hold address of next location in the memory to be accessed. • Memory Buffer Register (MBR): for storing data received from or sent to CPU. • Memory Data Register (MDR): for storing operand & data. • Accumulator (ACC): for storing the results produced by arithmetic & logic unit.

22. 1. Input Devices • Basic input devices : • Keyboard. • Mouse. • Special input devices: • Touch Screen • MICR (Magnetic Ink Character Reader) • Scanner • OCR (Optical Character Reader) • Joystick • Light pen • Trackball

23. 1(a) Keyboard most commonly used input device on which data is entered by manually keying in or typing certain keys. A keyboard typically has 101 or 105 keys.

24. 1(b) Mouse pointing device, which is used to control the movement of a mouse pointer on the screen to make selections from the screen. Mechanical Mouse A mouse has one to five buttons. The bottom of the mouse is flat and contains a mechanism that detects movement of the mouse. Optical Mouse

25. Special VDU (Visual Display Unit) devices have touch sensitive screens. • Recognize magnetically charged character • Uses magnetic ink for writting • Mainly found on bank cheques

26. OCR (Optical Character Reader) • Scan a particular document by recognizing its individual characters & converting it into the editable form. • OCR, distinguishes the dark area on the document from the light areas for recognizing the characters. OMR (Optical Mark Reader) • Scan only the box area • Helps in obtaining data from marked fields • E.g.: Multiple choice question paper. Bar Code Reader • Reads bar codes, which is used to label items in super markets • Bar codes are scanned, and later converted into number or letters using decoder.

27. Scanner • Used for digitizing images • Input device that can electronically capture text and images and convert them in to Computer readable form. • Types of scanner: • Hand held scanner • Flatbed scanner • Drum scanner Joystick • Pointing device • Consist of one or more buttons and a sticks, which controls the movements of the cursors on the screen. • Used to move cursor position on a monitor screen

28. Light pen • Pointing device • Used to select a displayed menu item or draw picture on screen • Consist of photocell & an optical system placed in a small tube • Detects screen location & sends corresponding signal to CPU Trackball • pointing devices • Looks and works like mouse

29. 3. Output Devices Most Commonly used are: Monitor Printer Others are: Plotters Projectors Voice output systems

30. 3(a): Monitor • is the display screen, similar to a television screen. • VDU (Visual Display Unit) • produces a soft copy of your output. Monitor Types based on Technology: • CRT : Cathode Ray Tube • LCD : Liquid Crystal Display • TFT : Thin Film Transistor Self Study (in detail)

31. Types of Monitor (depending upon number of pixels, resolution): • CGA : Colour Graphics Adapter. (310X320) (Text & graphics) • MDA : Monochrome Display Adapter (Text) • HGA : Hercules Graphics Adapter (310X320) (Text & Mono graphics) • EGA : Enhanced Graphics Adapter (640x350) (Text & Enhanced graphics) • VGA : Video Graphics Adapter (640x480) (Text & video graphics) • SVGA : Super VGA (1600x1280) (Text & video graphics)

32. 3(b): Printer • Is a computer hardware that produces a hard copy of information processed by a computer system. Types of Printers: • Impact Printers • Dot matrix printers • Daisy wheels printers • Drum printers • Non Impact Printers • Ink-jet printers : • Laser printers Self Study

33. Impact Printers • Printer in which there exist a mechanical contact between print head and paper. • Contains individual print head (resembles a hammer) for each character, print head responsible for transferring ink to the paper, • Print Head of a character strikes ink ribbon,ink ribbon in turn strikes paper, leaving an impression of that character on the paper. • Non Impact Printers • Printer in which there exist no mechanical contact between print head and paper. • Printer spray ink on the paper with the help of nozzle. • Do not produce noise, faster then impact printer

34. Dot Matrix Printer • Print character using dots • Speed measured in character /sec • Quite noise • Cheap

35. Inkjet printer: • Non impact printer • print character by spraying small drops of ink onto the paper. • Not very noise • Speed measured in character /sec

36. Laser Printer • Print character completely • Speed measured in pages • Not very noise • expensive

37. 4. Memory & Storage Devices • main types: • Data Storage (Secondary / Auxiliary memory) • Main Memory (Primary memory) • Internal process memory (Cache Memory & Registers) • Cost, • speed, • capacity 0 1 2 . . . . N Units of Storage – 1 bit – 8 bits = 1 byte – 1kbyte = 1024 bytes – 1Mbyte = 1024 Kbytes = 1048576 bytes – 1GB (Giga byte) = 1024 Mbytes – 1TB (Tera byte) = 1024 GB Memory Representation

38. 4(a): Memory • Memory is a work area within the computer where CPU used to stores data, instructions & information (bits and bytes) before, during & after the processing by ALU. • Temporary storage medium that holds the data only for a short period of time. • Also known asMain memory or Primary Memory or Internal memory • 2 types of Primary Memory: • RAM • ROM

39. RAM - Random Access Memory • Volatile • Temporary memory is the main memory of the computer. • information stored in RAM is lost when the computer is turned off. • It consists of electronic components that store data including numbers, letters of the alphabet, graphics and sound. • As it is possible to randomly use any location of this memory, therefore, this memory is known as “Random Access Memory”.

40. RAM E Static RAM Information stored in SRAM need not to be refreshed, but it remains stable as long as power supply is provided. SRAM has lesser storage capacity. It provides more speed to computer. It is costlier. Dynamic RAM • Information stored in DRAM has to be refreshed after every few milliseconds otherwise it is erased. • DRAM has higher storage capacity. • It provides lesser speed to computer. • It is cheaper. • SDRAM: Synchronous DRAM • Perform operation with use of system clock • ASRAM: Asynchronous SRAM • Perform operation without use of system clock

41. ROM - Read Only Memory Non-volatile Won’t disappear when power is off It is permanent memory. ROM is memory that is etched on a chip that has start-up directions for your computer. Most important program of ROM is BIOS (Basic Input Output System) that activates the hardware.

42. M Types of ROM • Mask ROM • Information is stored at the time of its manufacturing. • It cannot be altered or erased later on. • PROM (Programmable Read Only Memory) • Information is stored by programmer after its manufacturing. • It cannot be altered or erased later on. • EPROM (Erasable Programmable Read Only Memory) • Information is stored by programmer after its manufacturing. • but itsinformation can erased on by ultra violet light and it can be reprogrammed.

43. EEROM (Electrically Erasable Programmable Read Only Memory) • Information is stored by programmer after its manufacturing.. • but itsinformation can be erased by using high voltage current. • EAPROM (Electrically Alterable Programmable Read Only Memory) • Information is stored by programmer after its manufacturing. • information can be altered later

44. 4(b): Data Storage Secondary Memory or Auxiliary storage devices used to store data when they are not being used in memory. most common types of auxiliary storage used: floppy disks, hard disks and CD-ROM drives.

45. Disks Floppy Disk • Holds 1.44 Megabytes • 1,440,000 Bytes • Feels hard • Floppy part inside cover • Almost obsolete 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.

46. Floppy Disk contd.. • The disk’s storage locations are divided into pie-shaped sections called sectors. • A sectors is capable of holding 512 bytes of data. • A typical floppy stores data on both sides and has 80 tracks on each side with 18 sectors per track.

47. 4(b) Hard Disks • Main disk for most computers • Holds Windows, software, and most data • Usually don’t see it because it’s inside computer. • 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. • The hard disk platters spin at a high rate of speed, typically 5400 to 7200 revolutions per minute (RPM). • Storage capacities of hard disks for personal computers range from 120 GB to 1024GB (one billion bytes are called a gigabyte).

48. 4(c) Compact Discs (CD) • also called an optical disc, • is a flat round, portable storage medium that is usually 4.75 inch in diameter. • A CD-ROM (read only memory), is a compact disc that used the same laser technology as audio CDs for recording music. In addition it can contain other types of data such as text, graphics, and video. • The capacity of a CD-ROM is 650 MB of data.

49. DVD • Replacing CD-ROM • Holds much larger amount of information (such as movie) • 4.7GB

50. 4(c) Cache Memory • Small, fast, expensive memory that stores the copies of data that need to be accessed frequently from the main memory. Main Memory Cache Memory • Two Types of Cache Memory: • Primary Cache • known as “L1 Cache” or “Internal cache” , located inside the CPU. • Secondary Cache • known as “L2 Cache” or “Externalcache” , located on the motherboard of a computer. Processor