The document summarizes the five generations of computers from the 1940s to present. The first generation used vacuum tubes, the second used transistors, the third used integrated circuits, the fourth used microprocessors and personal computers, and the fifth generation uses ultra-large scale integration chips, larger storage, and internet connectivity. Each generation saw improvements in size, cost, reliability, speed, and commercial availability of computing.

1. GENERATIONS OF COMPUTER<br />Generation provides a framework for the growth of computer industry. The computer era consists of five generations till today.<br />FIRST GENERATION<br />Period: (1942-55)<br />Technology Used: Thousands of vacuum tubes<br />A vacuum tube is high speed electronic device, which used filaments as a source of electronics & could control and amplify electronic signals.

2. Memory used electromagnetic relays, data and instructions were fed into the system from punched cards.Software Technology Used<br />The instructions were written in machine and assembly languages.

3. The stored program concept was used.Key Characteristics<br />Bulky in size

4. Highly unreliable

5. Limited commercial use

6. Difficult commercial Production

7. Costly

8. Difficult to useExamples<br />ENAIC, EDVAC, EDSAC, UNIVAC I, IBM 701<br />SECOND GENERATION<br />Period: (1955-64)<br />Hardware Technology Used<br />Transistors because of following properties

9. Mode of germanium semiconductor

10. Highly reliable as compared to tubes

11. Could switch ten times faster than tubes

12. One-tenth the power consumed by tube

13. Smaller than a tube

14. Less expensive to produce

15. Dissipated less heat as compared to vacuum

16. Magnetic cores were used for main memory

17. Magnetic disks and tapes as secondary storage mediaSoftware Technology Used<br />High level programming languages (like FORTRAN, COBOL, ALGOL, SNOBOL) were used.

18. Batch operating system enabled multiple jobs to be batched together & submitted at a time.Key characteristics<br />Ten times faster than first generation computer

19. Smaller in size

20. Consumed less power and dissipated less heat

21. More reliable and less prone to hardware failure

22. Easier to program than previous generation systems

23. Commercial production was still difficult & costlyExamples<br />Honeywell 400, IBM 7030, CDC 1604, UNIVAC LARC<br />THIRD GENERATION<br />Period: (1964-75)<br />Hardware Technology Used: ICs<br />Integrated circuits are circuits consisting of several electronic components like transistors, resistors, and capacitors grown on a single silicon chip elimination wired interconnection b/w components.

24. Integrating about 10-20 components named as Small Scale Integration (SSI).

25. Later, Technology enhanced to integrate about 100 components on a single chip, known as Medium Scale Integration (MSI).

26. Larger magnetic core memory

27. Larger capacity magnetic disks & tapes as secondary storage

28. Mini computersSoftware Technology Used<br />Timesharing OS came into existence.

29. Standardization of high level languages (Fortran & COBOL).

30. Unbundling of software from hardwareKey Characteristics<br />Powerful, capable of performing about 1 million instructions per second

31. Smaller in size than second generation

32. Consumed less power & dissipated less heat

33. More reliable & less prone to hardware failures & requiring lower maintenance cost

34. Cheaper to produce commercially

35. Scientific, Commercial & Interactive online ApplicationsExample<br />IBM 360/370, PDP – 8, PDP -11, CDC 6600<br />FOURTH GENERATION<br />Period: (1975-89)<br /> <br />Hardware Technology Used<br />ICs with very large scale integration (VLSI) technology, capable of integrating 1 million components on a chip

36. A Microprocessor contains all circuits needed to perform arithmetic logic & control functions on a single chip

37. Semiconductor memory

38. Larger capacity hard disks as in-built secondary storage

39. Magnetic tapes & floppy disks as portable storage media

40. Personal computer

41. Spread of high speed computer networkSoftware Technology Used<br />OS like MS-DOS, Ms-Windows, Apple were developed for PCs

42. Graphical user Interface (GUI) provides icons and menus to make it user friendly

43. PC based applications like powerful word processing package, spread sheet package, etc.

44. Multiple windows on a single screen

45. UNIX OS

46. C programming language became popularKey Characteristics<br />PCs were smaller and cheaper than mainframes or minicomputers of third generation

47. Small, affordable, reliable, easy to use PCs

48. More powerful Mainframe systems

49. They were general purpose machines

50. Easier to produce commercially

51. Groupware is such application that allows multiple members working on a single project located at distant locations using network

52. Add-on Hardware feature that allows to invest only in hardware configuration & software of their need and valueExample<br />IBM PC, APPLE II, TRS 80, VAX 9000, CRAY-I, CRAY-2, CRAY-X<br />FIFTH GENERATION<br />Period: (1989-present)<br />Hardware Technology Used<br />ICs with ULSI (Ultra Large scale Integration) resulting in chips having ten million components

53. Larger capacity main memory

54. Larger capacity hard disks

55. Optical disks as portable read only storage media

56. Notebook Computers

57. Powerful desktop PCs & workstations

58. Very powerful mainframe

59. The InternetSoftware Technology Used<br />A vast ocean of information became readily available to computer users through World Wide Web (www)

60. Multimedia applications

61. Internet based applications like e-mailKey Characteristics<br />Portable computers

62. More powerful, cheaper, reliable

63. Easier to use desktop machines

64. Very powerful mainframes

65. Very high uptime due to hot pluggable components

66. General purpose machines

67. Easier to produce commerciallyExample<br />IBM, Notebooks, Pentium PCs, SUN Workstations, IBM SP/2, PARAM 10000<br />