1. COMPUTER SCIENCE PROJECT WORK FOR III UNIT TEST

2. 2 MADE BY: AMIT KUMAR BHIM KUMAR CHITRANJAN GUIDED BY: MR. LOKESH SAINI

3. 3 History Of Computing Computer Hardware

4. 4 Computer Development Computer architecture  Overview

5. 5  Introduction Computer is arguably the most important tool in the areas of engineering, science, business etc. etc. Data acquisition and analysis Simulation Embedded applications Process control Condition monitoring and fault diagnosis systems Automatic testing equipment Robotics Telecommunications Productivity software (word processing, spreadsheets, databases, presentation) etc……………

6. 6  Computer development The Abacus- Babylonia-4 th century B.C. The Difference Engine- Charles Babbage 1822 Vacuum tube - John Ambrose Fleming 1904 The ENIAC (Electronic Numerical Integrator and Computer)-1945 Used 17,478 vacuum tubes Too late for WW-II, but was used in the cold war to perform calculations to build a hydrogen bomb

7. 7 City of Philadelphia reportedly experienced brown-outs when ENIAC drew power at its home at the the University of Pennsylvania (http://www.pbs.org/wgbh/aso/databank/entries/dt45en.html) Was not a general purpose computer: programming meant rewiring with punch cards and switches One of ENIAC's greatest feats was in showing the potential of what could be accomplished in the future Transistor - Nobel prize in physics in 1956

8. 8 Integrated Circuit (chip) - Jack Kilby 1958 (Nobel prize in physics in 2000) First commercially available IC’s developed by Texas Instruments and Fairchild semiconductor corp. Generations of IC’s: Small scale integration - 1965 Up to 100 devices on a chip Medium scale integration - to 1971 100-3,000 devices on a chip Large scale integration - 1971-1977 3,000 - 100,000 devices on a chip Very large scale integration - 1978 to date 100,000 - 100,000,000 devices on a chip Ultra large scale integration Over 100,000,000 devices on a chip Apple I computer (1976)

9. 9 Moore’s Law: Number of transistors on a chip will double every 18 months.

10. 10  Computer Architecture Main Memory Input Output Systems Interconnection Central Processing Unit

11. 11 Components of a Computer System central processing unit Storage (External memory) input/output Main Memory (RAM)

12. 12 Computer Components

13. 13 Component description Central Processing Unit (CPU) or microprocessor, controls the operation of the computer and performs its data processing functions Main memory - also called internal memory stores instructions and data. Memory is partitioned into separate instruction and data spaces Input/output (I/O) – moves data between the computer and its external environment System interconnection – some mechanism that provides for communications among the CPU, the main memory, and the I/O devices

14. 14 Structure of the CPU control unit registers flags cache memory ALU input/output storage memory registers

15. 15 Components of the CPU Arithmetic and Logic Unit (ALU): processes the data in the registers according to instructions issued by the control unit. Performs arithmetic (addition, subtraction, etc..) and logical (comparison) operations Registers: provides temporary storage for data and instructions. It handles instructions and data at 10 times the speed of cache memory. Registers facilitate the movement of data and instructions between RAM, the control unit and the ALU Control unit registers: The instruction register contains the current instruction being executed The program register (instruction pointer) contains the RAM address of the next instruction to be executed ALU registers The accumulator register stores the result of ALU operations

16. 16 Internal CPU interconnection: some mechanism that provides for communication among the control unit, ALU, and registers Control Unit: controls the operation of the CPU and hence the computer. Interprets instructions, moves data to/from memory and registers, instructs ALU to perform certain operations, increments instruction pointer, etc. During program execution, instructions in a program are moved from the RAM into the control unit, where it is decoded and interpreted by the decoder Flags: 1-bit memory, or 1-bit registers and hold information on what has recently happened in the CPU. These are set to 1 or 0 depending on the results of internal operations such as results of ALU operations (zero or negative result) or external operations such as interrupts (commands that tell the processor to stop execution and wait for further instruction)

17. 17 Cache Memory: Small fast memory that improves CPU’s efficiency. Increases computer throughput, and is a high-speed holding area for program instructions and data. It holds only instructions and data that are likely to be needed by the CPU. While programs are running on the computer, the same data or instructions might be needed frequently. In such cases, the processor first checks the cache memory for the data or instructions, thereby reducing the need for frequent access to the RAM and speeding up the processing

18. 18 Microprocessor System Buses Microprocessor (CPU) RAM ROM Input/Output (I/O) Control Bus Data Bus Address Bus

19. 19 System Buses A BUS is an internal communications path consisting of a number of lines connecting the system components Control bus –The control bus synchronizes system events like memory access, system interrupts, I/O, etc. Address bus – Source and destination addresses are sent over the address bus to identify a particular location in memory or input/output port. Data bus – two way path for transferring data and instructions in and out of the microprocessor

20. 20 Main Memory A collection of cells Each cell has an address and a value Random Access Memory (RAM) Cells can be accessed randomly Ram is volatile All data stored in binary format Bit, byte and word are the unit of data

21. 21 Main Memory RAM – Random Access Memory. Temporary read/write memory. Applications are typically loaded into RAM during computer use. Types of RAM include: SRAM (static), DRAM (dynamic ), EDO RAM (extended data out), SDRAM (synchronous dynamic-most new PC’s are equipped with this RAM which is able to synchronize itself with the processor, enabling data transfer at more than twice the speed of previous RAM technologies) SRAM is called static because the memory retains its contents as long as power is supplied-It does not have to be periodically refreshed as in DRAM. It is faster than DRAM (The contents of the memory can be read much faster), however is more expensive and is larger in size DRAM is called Dynamic RAM because the memory content needs to be refreshed periodically (every few milliseconds) due to leakage of electrical charge. It is slower than SRAM, but cheaper and smaller in size

22. 22 CPU-Memory Interaction 0LDA 14 1ADD 15 2STA 14 3HLT ….…… 1410 157 1417 157 Assume a is stored in 14 and b is stored in 15 a= a + b Result Program Fetch-execute cycle

23. 23 ROM – Read Only Memory. ROM can typically be written once, but read many times. It is used to store BIOS (Basic Input/Output System-helps to load and locate an operating system), external to microprocessor, and computer instruction sets, internal to microprocessor The contents of the ROM are hard wired by the manufacturer in a typical ROM chip. When you turn the computer on, ROM automatically prepares the computer system and loads the initial display screen prompt A variation of ROM is PROM (Programmable Read Only Memory), in which the user can load programs and data that are read only. This can be done with device called a PROM programmer. Writing to a PROM destroys the internal links, so a basic PROM can only be programmed once

24. 24 EPROMs (Erasable Programmable Read Only Memory) is a variation of PROM, and is rewritable. It can be erased by exposing the chip to ultraviolet light. It can then be programmed with an EPROM programmer Flash memory is a type of PROM that can be easily altered by the user. They are also called EEPROMs (Electrically Erasable Read Only Memory) because they can be electrically erased then written on to (flashed) without having to take them out of the computer, and without using ultraviolet light. Since RAM can be read faster than most ROMs, the frequently used content of the ROM is sometimes copied to RAM (shadowed)

25. 25 Secondary Storage Magnetic disk Hard disk (File, Directory, Folder) Floppy disks Zip disks Optical media CD (680 MB) DVD (4.7 GB) Magneto-optical disks (Pinnacle drives) Magnetic tape (used primarily for long term archive)

26. 26 Hard Disk Drive Basics

27. 27 Input/Output Some Input Devices Keyboard Keypad Mouse Voice activation Touch screen Digitizers and pen-based (stylus) systems

28. 28 Some Output Devices Monitor Printer Speakers Communication (comm) ports Modems (both input and output) Network interface cards (both input and output)

29. 29 Input and Output Devices and Systems

30. 30 Storage System Issues Historical Context of Storage and I/O Secondary and Tertiary Storage Devices Storage I/O Performance Measures Queuing Theory Processor Interface Issues I/O Buses Redundant Arrays of Inexpensive Disks (RAID) File Systems I/O Benchmarks File System Performance

31. IT Fundamentals31 Input device is a tool used to capture information and commands Examples include: Keyboard Point-of-sale (POS) Microphone Mouse Pointing stick Touch pad Touch screen Bar code reader Optical mark recognition (OMR) Scanner

32. IT Fundamentals32 Types of input

33. IT Fundamentals33 Input Devices Most obvious = human + KEYBOARD Machines make better input devices…. DIRECT ENTRY, or SOURCE DATA AUTOMATION. Need to be: Accurate, reliable and easy to use, fast Human and keyboard is the most used input device

34. IT Fundamentals34 Examples of Direct Entry Input Devices MICR : Used with cheques OMR : Tattslotto & TAB OCR : Scan type-written pages…. Scanners

35. IT Fundamentals35 Examples of Direct Entry Input Devices Barcode Readers: Sit-in-the-Counter type -Reads standard or customised barcodes

36. IT Fundamentals36 Input Types a. Data Collection Devices: Web Cams Video camera whose output displays on a web page Digital Camera

37. IT Fundamentals37 Other Input Devices a. Sensors Pointing Devices Mouse measures x-y moveent plus whether button is pressed down…

38. IT Fundamentals38 Other Input Devices TouchPad Pointing Stick Light Pen Trackball - Similar to mouse Joystick -games? -Difficult to pinpoint a position Touch screens screen 'divided' into areas area selected by touch easy to use cannot have areas too small screens get dirty (many uses)

39. IT Fundamentals39 Voice Input

40. IT Fundamentals40 Output Four common type of output are text, graphics, audio and video.

41. IT Fundamentals41 Output Output Devices Digital signals from computer are converted into human readable form. Hard Copy Soft Copy

42. IT Fundamentals42 Output Printers Impact printers Dot Matrix:

43. IT Fundamentals43 Output Non-impact printers -no physical contact between paper and printing device -3 technologies used: ink jet - thermal -special paper -expensive to run -up to photographic quality…

44. IT Fundamentals44 Output Laser -need enough memory to hold an entire page -600 to 2400 dpi and greater -operates similar to a photocopy machine…

45. IT Fundamentals45 Output CRT Monitors Raster scan technology An electron beam moves back and forward across the back of the screen This causes dots on the front of the screen to glow, producing an image Available in various sizes 15 – 22 inches Flat and curved screens Resolution CRT monitors ( 1280 X 1024 pixels) High end CRT monitors (2048 X 1536 pixels)….

46. IT Fundamentals46 Output

47. IT Fundamentals47 Output LCD Monitors An electric current passes through the crystals causing them to twist, block light waves and create an image. Gas Plasma Monitors Very high quality (1080p)…. Larger screens

48. IT Fundamentals48 Other Output Devices Data Projectors

49. IT Fundamentals49 Other Output Devices Fax Machine Transmits and receives documents over the telephone line

50. IT Fundamentals50 Other Output Devices Multifunction devices Printer, scanner, copy machine and fax machine all in one

51. 51 SECONDARY STORAGE Control Unit works on programs/data in RAM POWER OFF... RAM OFF Bye Bye Assignment However blocks of memory can be saved/read on secondary storage.

52. 52 Secondary Storage Media and Devices Floppy Disks Hard Disks Tape and Tape drive Cartridge tape CD-ROM/DVD/BluRay Magnetic-Optical drive PC Cards Smart Cards USB Drives SECONDARY STORAGE

53. 53 Size Type Tracks Sectors Capacity IBM: 3½ DD 80 9 720KB 3½ HD 80 18 1.44MB Macintosh 3½ HD 1.4MB FLOPPY DISKS: eg. for a 3½ disk (high density): 3 1/2-inch diskette Circular piece of plastic Made up of tracks & sectors 512 bytes in each sector

54. 54 Made up of platters, cylinders and sectors Rotation speed 7200 rpm head 'floats' on surface bad sectors & head crash HARD DISKS

55. 55 OPTICAL STORAGE TECHNOLOGY CD-ROM (compact disk read-only memory)- 650 MB of information DVD (digital video disk) - 4.7 gigabytes CD-R (compact disk-recordable) CD-RW (compact disk-rewritable) Magneto-optical (MO) – combines magnetic/optical technology by changing polarity of spot (1 to 0 etc.) Hard Disk Vs Floppy Disk

56. 56 Compact Disk Read Only Memory high capacity is ideal for storage of the very large sound, graphics and video files when recording data, laser light burns pits on CD when reading data, pits will not reflect light (binary bit 0) but lands will reflect light (binary bit 1) CDROM

57. 57 Other Storage Devices Tape Thin ribbon of plastic Sequential storage – mainly for backup Used for longer term storage USB Flash Drives plugs into a USB port Small, lightweight Storage 4 GB + Great for mobile users

58. 58 OTHER TYPES OF STORAGE DEVICES PC cards Small, credit card-sized cards that fit into PC Card expansion slots Used for storage, communications and additional memory. Most often used with portable computers Can store more than 300 MB of data Smart Cards Credit card-sized devices that contain a microprocessor Microprocessor can store up to 8,000 bytes of information. Examples of uses - prepaid telephone card, employee time card