Processor Components

(a)   sends out signals to co-ordinate how the processor works and instructions are decoded here.

• Control Unit (CU)
• Central Processing Unit (CPU)
• Arithmetic Logic Unit (ALU)
• Current Instruction Register (CIR)

(a)   carries out the calculations and logical decisions.  The results of its calculations are stored in the accumulator.

• Control Unit (CU)
• Arithmetic Logic Unit (ALU)
• Accumulator (ACC)
• Memory Data Register (MDR)

Holds the address of the next instruction to be executed.  It gets incremented with each cycle of the fetch-decode-execute cycle. 

• Memory Address Register (MAR)
• Current Instruction Register (CIR)
• Program Counter (PC)
• Accumulator (ACC)

Stores the data that has been fetched from or stored in memory.

• Memory Data Register (MDR)
• Data Bus
• Memory Address Register (MAR)
• Current Instruction Register (CIR)

Stores the address of the data or instructions that are to be fetched from or sent to.

• Address Bus
• Memory Address Register (MAR)
• Memory Data Register (MDR)
• Data Bus

The ALU makes calculations and stores the results in the (a)   .

• Memory Data Register (MDR)
• Control Unit (CU)
• Accumulator (ACC)
• Program Counter (PC)

Stores the most recently fetched instruction, waiting to be decoded.

• Program Counter (PC)
• Memory Data Register (MDR)
• Control Unit (CU)
• Current Instruction Register (CIR)

Used to transmit data between areas of the processor.

• Data Bus
• Address Bus
• Memory Data Register (MDR)
• Control Unit (CU)

Used to carry the address to which the data is being transmitted.

• Control Bus
• Address Bus
• Memory Address Register (MAR)
• Memory Data Register (MDR)

_____ is used to send control signals from control unit to other parts of the processor