CPU Structure




Control Unit

This manages the hardware (both input and output) on a computer to make sure data goes to the right place and in the correct order.

Manages the Fetch-Decode-Execute cycle.


Arithmetic Logic Unit

The Arithmetic unit carries out calculations (adding numbers etc).

The Logic unit compares calculations (to see which is bigger for example).


Registers

Current Instruction Register (CIR): Holds the current instruction that is being operated. Held into operand and operate.

Memory Address Register (MAR): Holds the address of the memory location from which data (instructions) is to be fetched or to which data is to be written.

Memory Data Register (MDR): Used to temporarily store the data read from or written to memory. Is known as the memory buffer register.


 Program Counter (PC)

Holds the address of the next instruction to be executed.


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