Structure & Function of the Processor

Structure & Function of the Processor

1. A computer system is made up of hardware and software that work together in order to make a complete system that can process data and instructions using the processor

   • Hardware is anything physical that you can touch with your hands
     • Examples include: a keyboard, a monitor or a stick of RAM
   • Software are the programs (or sets of instructions) that tell the hardware to do useful things
     • Examples include: word processors, operating systems and games
   • A Peripheral is a piece of hardware that you can connect to a computer by plugging it into a USB port of via wireless connection such as bluetooth

2. Central Processing Unit

   • Arithmetic Logic Unit
     • The ALU carries out calculations and logical decisions
       • The results of its calculations are stored in the accumulator
       • It can perform arithmetic calculations on data, e.g adding two binary numbers together
       • It can perform logical operations on data e.g AND, OR NOT comparisons
       • Holds data that has already been worked on, ready to be processed
   • Control Unit
     • Sends out signals to coordinate how the processor works. It controls how data moves around and between the processor and memory
       • Controls the fetch decode execute cycle
         • Fetches instructions from wherever they are stored in the memory unit
           • Decodes instructions so that it knows what needs to be done
             • It then executes the instruction
   • Registers
     • These are memory locations within the processor itself, storing data and instructions
     • Program Counter
     • Current Instruction Register
     • Memory Address Register
     • Memory Data Register
     • Accumulator
   • Main memory
     • This is where instructions and data that is needed by programs are held, ready to be fetched decoded and executed by the CPU
       • It is a set of memory locations