OCR Computing Chapter 2

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  • Ch. 2 - Hardware
    • The CPU
      • Cache memory - expensive, very fast, reduces delay from main memory
      • Clock speed = cycles per second
      • Multiple cores - faster but needs better OS
      • Carries out all processing, Fetch, decode, execute
    • Secondary Storage
      • Optical Disk: less reliable, OK capacity, portable, light, cheap
      • Flash Memory less reliable, high capacity, portable, light, expensive
      • Magnetic Disk reliable, very high capacity, heavy, fragile, cheap
    • Output devices
      • Speaker
      • Printer
      • Plotter
      • Monitor
      • Actuator
    • Binary Logic
      • Binary used - switch is either on or off (easy)
      • AND, OR and NOT gates
      • Data & instructions stored together as binary in RAM
    • Memory
      • Flash Memory portable -USB type of ROM that can be rewritten. Advances in flash led to smartphones
      • RAM - volatile, can be changed, contains OS and data in use. Small - 2MB
      • ROM -      non-volatile. Programmed during manufacture, stores start up data and boot program. Large - 4+GB
      • Virtual Memory: used as an extension to RAM if there isn't enough. Slower than RAM
    • Input Devices
      • Keyboard, Microphone, Mouse, Touchscreen, Camera, Sensors
      • Disability: Eye typer, puff-**** switch, foot mouse, braille keyboard


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