Computer Hardware

Computer Hardware

1. The CPU

   • Carries out all the processing in the computer
   • The ALU carries out the arithmetic and logical operations.
   • The control unit controls flow of data in the CPU.
   • Carries out the fetch-decode-execute cycle.
   • Speed depends on clock speed, cache memory, number of processor cores
   • Data is transferred to cache to make access faster
   • Multiple cores work simultaneously.

2. Memory

   • ROM is non volatile, stores instructions and data to start up computer, contains boot program, small memory, programmed during manufacture
   • RAM is volatile, stores program and data being used, contains operating system, large memory, can be accessed and changed at any time.
   • Virtual memory is used when RAM is full
   • Flash memory is ROM that can be rewritten. It is portable and easy to use.

3. Secondary Storage

   • Needed to store data when power is switched off
   • Flash Memory
     • Good Capacity
     • Used in hand-held devices
     • More expensive than a hard disk
   • Optical Disk
     • Low Cost
     • Good Cacpacity
     • Lightweight and Portable
   • Magnetic Hard Disk
     • Reliable
     • High Capacity
     • Low Cost
   • Considerations
     • Capacity
     • Speed
     • Portability
     • Durability
     • Reliability

4. Input and Output Devices

   • Input
     • Used to input data for processing into the computer
     • Keyboard - Used for data entry
     • Mouse - Controls a pointer on scree that can be opened, dragged or controlled
     • Touch Screen - Allows the user to directly interact with icons
     • Microphone - Uses voice input to communicate/control the device
     • Camera - Captures images or video
     • Bar Code Scanner - reads light reflected back from a pattern on thick and thin lines.
     • Sensor - Detects physical conditions and collects data
   • Output
     • Used to output processed data from the computer
     • Monitor - Displays text/images/video
     • Printer - Produces hard copy on paper
     • Speakers - Produces sound output
     • Plotter - Reproduces large-scale engineering or architectural drawings