Computer Systems Revision

Computer Systems Revision

1. Hardware

   • Input Devices
     • Mouse, Keyboard, Biometric Scanner
   • Output Devices
     • Monitor, Printer, Speaker
   • CPU
     • Carries out all processing in computer, made from billions of transitors to build logic gates.
       • Measured in Hertz, number of cycles per second / clock speed. E.g. 2 MHz = 2 billion instructions executed per second.
       • ALU
         • All calculations and logical decisions made by this.
       • Control Unit
         • Control Unit decodes instructions and sends out signals to control how data moves around CPU to execute instructions.
       • A bus is a communication channel through which data can be moved, they enable data and control signals to move around the CPU.
         • Data Bus - carries data between CPU and memory.
           • Bi-Directional
         • Control Bus - carries control signals around CPU and memory.
         • Address Bus - carries memory addresses for locations to be read or written to.
           • Uni-Directional

2. Software

   • Programs, eg. PowerPoint

3. Input --> Process --> Output

4. Types: General Purpose, Dedicated, Control and Embedded.

   • Dedicated Systems are dedicated for a specific job, like a ticket vending machine.
   • Control Systems are designed to control machinery, important in manufacturing process.
   • Embedded Systems are parts that forms an electronic device, for example in washing machines and in telephones.
     • Advantages include low powered, small, rugged, low cost and dedicated to one task, making it simpler.