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Basic Computer Skills


                        Notes            4. They were more reliable and less prone to hardware failures than second-generation
                                           computers requiring lower maintenance cost.
                                         5. They had faster  and larger primary and secondary storage as compared to second-
                                           generation computers.
                                         6. They were general-purpose machines suitable for both scientific and commercial
                                           applications.
                                         7. There manufacturing did not require manual assembly of individual components into
                                           electronic circuits resulting in reduced human labor and cost involved at assembly

                                           stage. Hence, commercial production of these systems was easier and cheaper. However,

                                           highly sophisticated technology and expensive setup was required for the manufacture
                                           of IC chips.
                                         8. Standardization of high-level programming languages allowed programs written for
                                           one computer to be easily ported to and executed on another computer.
                                         9. Timesharing operating system allowed interactive usage and simultaneous use of these
                                           systems by multiple users.
                                        10. Timesharing operating system helped in drastically improving the productivity of
                                           programmers down the time and cost of program development by several fold.
                                        11. Timesharing operating system also made on-line systems feasible resulting in usage
                                           of these systems oil-line applications.
                                        12. Unbundling of software from hardware gave users of these systems an opportunity to
                                           invest only in software of their need and value.
                                        13. Minicomputers of third-generation made computers affordable even by smaller
                                           companies.
                                       1.3.4 Fourth Generation (1975-1989)
                                       Average of electronic components packed on a silicon chip doubled each year after 1965. This
                                       progress soon led to the era of  large scale integration  (ISI) when it was possible to integrate
                                       over 30,000 electronic components on a single chip, followed by  very large scale integration
                                       (VLSI) when it was possible to integrate about one million electronic components on a single
                                       chip. This progress led to a dramatic development — creation of a microprocessor.
                                       A microprocessor contains all circuits needed to perform arithmetic logic and control: functions,
                                       the core activities of all computers, on a single chip. Hence, it became possible to build a
                                       complete computer with a Microprocessor, a few additional primary storage chips, and other
                                       support circuitry. It started a new social revolution—personal computer (PC)  revolution.
                                       Overnight computers became incredibly compact. They become inexpensive to make, and
                                       suddenly it became possible for anyone to own a computer.
                                       During forth generation, semiconductor memories replaced magnetic core memories resulting
                                       in large random access memories with very fast access time. On the other hand, hard disks
                                       became cheaper, smaller, and larger in capacity. In addition to magnetic tapes, floppy disks
                                       became very popular as a portable medium for porting programs and data from one computer
                                       system to another.

                                       Another significant development during fourth-generation period was spread of high-speed
                                       computer networking enabling interconnection of multiple computers to enable them to
                                       communicate and share data. Local area networks (LANs) became popular for connecting





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