Unit 1 - Components of a computer & their uses

Unit 1 - Components of a computer & their uses

1. T1 - Processor Components

   • Central Processing Unit (CPU)
     • The processor has a number of different components, each with their own role to perform
       • Control Unit
       • Buses
       • Arithmetic Logic Unit (ALU)
       • Dedicated registers
   • Control Unit
     • The part of the processor that coordinates the activity of all other components
       • Control signals are sent along the control bus between the control unit and the other components of the computer
   • Buses
     • Buses in a computer consist of a series of connectors that transfer signals between internal components. They typically consist of 8, 16, 32, 64 lines
     • System bus
       • The system bus cosists of three seperate buses carrying control signals, addresses and data
         • Control Bus
           • Carries control signals from the processor to other components. The control bus can also carry clock pulses
         • Data Bus
           • Carries the data between the processor and other components. The data bus is bidirectional meaning that data can flow in both directions
         • Address Bus
           • The purpose of the address bus is to identify the address of the location in cache or main memory that is to be read from or written to
   • Control Signals
     • Memory Read - causes data from the addressed location in RAM to be placed on the data bus
     • Memory write - causes data on the data bus to be written into the addressed location in RAM
     • Bus request - indicates that a device is requesting use of the data bus
     • Bus grant - indicates that the CPU has granted access to the data bus
     • Clock - used to synchronise operations
   • Arithmetic Logic Unit (ALU)
     • This is the problem solving part of the processor. This component performs arithmetic, logical and shift operations on data
       • Arithmetic operations
         • Add
         • Subtract
         • Multiply
         • Divide
       • Logical operations
         • AND
         • OR
         • NOT
         • XOR
       • Shift operations
         • Move bits to the left or right within a register
     • The accumulator