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Computers, HW and SW

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• computer
  1982 ¡§Man of the Year¡¨ by TIME Magazine
• what is a computer
  tool/machine to solve a problem
  performs computation faster than us
  Hardware(CPU, memory, I/O), Operating System, Applications, Users(Chinese, British, French, or other computers)
• Six logical units of computer system
  
  1. Input unit
     Mouse, keyboard
  2. Output unit
     Printer, monitor, audio speakers
  3. Memory unit
     Retains input and processed information
  4. Arithmetic and logic unit (ALU)
     Performs calculations
  5. Central processing unit (CPU)
     Supervises operation of other devices
  6. Secondary storage unit
     Hard drives, floppy drives
• Operating Systems
  the one program running at all times on the computer (Kernel)
  batch, interactive, time-sharing, real-time, distributed
  CP/M, PC DOS, MS DOS, MS Windows 3.1 /NT /95 /98/2K/XP, OS/2,OS/360, Macintosh, Unix, VMS, MVS
  perform common functions of controlling and allocating resources(CPU, memory, file storage space, I/O devices)
  1. Processor management:
     process creation, suspension, resumption, communication and destruction; interrupts; and Scheduling
     
  2. Memory management:
     single-user monitor, multiprogramming, virtual memory
  3. File management:
     storage of files and directories
     
  4. Protection and security:
     access control, authentication, and encryptions
  5. User interaction:
     command interpreter, ¡§Window system¡¨
• Personal, Distributed and Client/Server Computing
  
  • Personal computing
    Computers for personal use
  • Distributed computing
    Computing performed among several computers
  • Client/server computing
    Servers offer common store of programs and data
    Clients access programs and data from server

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