2 history of computers

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2 history of computers

  1. 1. Overview of Computer Hardware Computer Generations Classification of Computer System Computer System Concept Computer Peripherals
  2. 2. Computer Generations  First Generation Computer – Early 1950s. – Used thousands of vacuum tubes for processing and memory switching. – Used magnetic drums or tape secondary storage – Used paper tape as Input and Output media. – Has main memory of only a few thousand character.
  3. 3. Computer Generations  Second Generation Computer – Late 1960s. – Used transistors and other solid-state semiconductor devices. – Main memory capacities of less than 100 kilobytes. – Magnetic disk packs and magnetic tape were used as I/O and secondary storage medium.
  4. 4. Computer Generations  Third Generation Computers – 1970s – Used integrated circuits. – Main memory capacities increased to several megabytes. – Possible used of operating system program. – Wide spread use of small computer called microcomputer.
  5. 5. Computer Generations  Fourth Generation Computers – 1980s and 1990s – Used LSI and VLSI technologies. – Used microprocessor. – Magnetic core memory is replaced by memory chips. – Main memory capacity ranging from a few megabytes to several gigabytes.  Fifth Generation Computer – as we enter 21st century.
  6. 6. Classification of Computer System  Microcomputer System  Midrange Computer System  Mainframe Computer System
  7. 7. Classification of Computer System  Microcomputer System – Usually called personal computer or PC. – Variety of size and purpose, e.g. handheld, notebook, desktop. – Workstation computers – Network servers – Personal Digital Assistants (PDA) – Multimedial PC – Network Computer.
  8. 8. Classification of Computer System  Network computer
  9. 9. Classification of Computer System  Midrange Computer System – Multi-user system that can manage networks of PCs and terminals. – Includes minicomputers and high-end network servers. – Not as powerful as mainframe computers but less costly to buy, operate and maintain than mainframe system. – Serves as industrial process-control and manufacturing plant computers. – Popular as network server.
  10. 10. Classification of Computer System  IBM Netfinity
  11. 11. Classification of Computer System  Mainframe Computer System – Large, fast and powerful computer. – Can process hundreds of million instruction per second. – Has large primary storage capacity. – Handle information processing needs of major corporation and government agencies or with complex computational problems. – Used as superserver for large client/networks and high volume internet website. – Supercomputer
  12. 12. Classification of Computer System  IBM S/
  13. 13. Classification of Computer System  Supercomputer IBM RS/ SP
  14. 14. Computer System Concept  Computer is a system of hardware devices organized according to the following system functions  Input  Processing  Control  Output  Storage
  15. 15. Computer System Concept
  16. 16. Computer System Concept  Central Processing Unit (CPU) – most important hardware component of a computer system – divided into two subunits  Arithmetic-Logic Unit or ALU  Control Unit
  17. 17. Computer System Concept  Intel Pentium II microprocessor
  18. 18. Computer System Concept  Primary Storage – commonly called main memory – holds data and program instruction between processing step – most computer memory consists of microelectronic semiconductor memory chips known as  RAM ( Random Access Memory )  ROM ( Read Only Memory )
  19. 19. Computer System Concept  Secondary Storage – devices like magnetic disks, optical disk ,etc. – has larger storage capacity than computer main memory – play supporting role to primary storage and computer system.
  20. 20. Computer System Concept  Multiple Processor Designs. – Support Processor  relies on specialized microprocessors to help the main CPU perform a variety of functions.  E.g. arithmetic co-processor, video display controller, etc. – Coupled Processor  uses multiple CPU or main microprocessor.  Executing more than one instruction at the same time.
  21. 21. Computer System Concept  Multiple Processor Designs (continued) – Parallel Processor  uses group of instruction processor to execute several program instruction in parallel.  hundreds or thousands of processor are organized in network. – RISC Processor  Reduced Instruction Set Computer  uses smaller number of basic machine instruction.  Required more complex software.
  22. 22. Computer Peripherals  Input Technologies – keyboard – pointing device. E.g. electronic mouse, track ball, pointing stick, touch pad, touch screen – pen-based computing – voice recognition and response – optical scanning – magnetic stripe – digital cameras
  23. 23. Computer Peripherals  Output Technologies – Video output  Video monitor  Liquid Crystal Display (LCD) – Printed output  Inkjet printer  Laser printer
  24. 24. Computer Peripherals  Pen-based tablet recognizes handwriting on its display screen

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