• Secondary Memory Devices
  • Input / Output Devices
  • Software Categories
  • Analog vs. Digital
  • Digital Information
  • Representing Text Digitally
  • Binary Numbers
    		•

    Chapter 1: Computer Systems




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    slides01

    CPU and Main Memory

    • Central
    • Processing
    • Unit
    • Main
    • Memory
    • Chip that executes program commands
    • Intel Pentium III
    • Sun Sparc Processor
    • Primary storage area for programs and data that are in active use
    • Synonymous with RAM

    Secondary Memory Devices

    • Floppy Disk
    • Hard Disk
    • Main
    • Memory
    • Central
    • Processing
    • Unit
    • Secondary memory
    • devices provide
    • long-term storage
    • Information is moved
    • between main memory
    • and secondary memory
    • as needed
    • Hard disks
    • Floppy disks
    • ZIP disks
    • Writable CDs
    • Tapes

    Input / Output Devices

    • Monitor
    • Keyboard
    • Main
    • Memory
    • Central
    • Processing
    • Unit
    • Floppy Disk
    • Hard Disk
    • I/O devices allow user
    • interaction
    • Monitor screen
    • Keyboard
    • Mouse
    • Bar code scanner
    • Light pen
    • Touch screen

    Software Categories

    • Operating System
      • controls all machine activities
      • provides the user interface to the computer
      • manages resources such as the CPU and memory
      • Windows 98, Windows NT, Unix, Linux, Mac OS
    • Application program
    • Most operating systems and application programs have a graphical user interface (GUI)

    Analog vs. Digital

    • There are two basic ways to store and manage data:
    • Analog
      • continuous, in direct proportion to the data represented
      • music on a record album - a needle rides on ridges in the grooves that are directly proportional to the voltage sent to the speaker
    • Digital
      • the information is broken down into pieces, and each piece is represented separately
      • music on a compact disc - the disc stores numbers representing specific voltage levels sampled at various points

    Digital Information

    • Computers store all information digitally:
      • numbers
      • text
      • graphics and images
      • audio
      • video
      • program instructions
    • In some way, all information is digitized - broken down into pieces and represented as numbers

    Representing Text Digitally

    • For example, every character is stored as a number, including spaces, digits, and punctuation
    • Corresponding upper and lower case letters are separate characters
    • H i , H e a t h e r .
    • 72 105 44 32 72 101 97 116 104 101 114 46

    Binary Numbers

    • Once information is digitized, it is represented and stored in memory using the binary number system
    • A single binary digit (0 or 1) is called a bit
    • Devices that store and move information are cheaper and more reliable if they only have to represent two states
    • A single bit can represent two possible states, like a light bulb that is either on (1) or off (0)
    • Combinations of bits are used to store values

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