This week in computing, our class learnt about the processor. Within the processor, there are the control unit, ALU, MAR, MDR and Registers.
Von Neumann Architecture.
Inside the Processor
ALU: This is the arithmetic and logic unit. This part of the processor carries out all the arithmetic calculations and logical operations (AND, OR, NOT) the computer is asked to do.
Control Unit: This part of the processor controls the fetching and executing of instructions. It keeps everything synchronised and manages the reading and writing to and from the main memory. #
General purpose registers: These are very fast temporary storage locations on the processor.
MAR: The Memory Address Register is the register which holds the unique storage location of what piece of information is needed from the main memory
MDR: The Memory Data Register is the register which the information from the main memory is retrieved and also where it is sent back to the main memory if it is re-written or slightly changed.
Buses: These are physical wires which connect each part of the processor together.
The Control Bus
Each wire on the control bus has its own separate function. There are five:
Read Line: This informs the memory that data has been sent to the processor from a particular memory location.
Write Line: It informs the memory that data is to be written to a specific memory location.
Interrupt: A message which is received from a peripheral device causes the processor to stop doing the current task and deal with the message from the peripheral. Current data is stored into a temporary storage location on the processor called the stack. The processor then deals with the interrupt and once the task has done, it retrieves the data from the stack and carries on with the task.
Clock: This line keeps everything synchronised. It generates a steady pulse which keeps the flow of information constant.
Reset: This line clears all the internal processor registers and switches the computer back to its original switched on state.