The Central Processing Unit (CPU): Architecture

What is OP code?

​ The memory address held in the ​ (a)   is copied into the ​ (b)   .

1. The address in the ​ (c)   is then incremented (increased) by one. The program counter now holds the address of the ​next instruction to be fetched.

2. The processor sends a signal along the ​ (d)   to the memory address held in the MAR.

3. The instruction/data held in that memory address is sent along the data bus to the MDR.

4. The instruction/data held in the MDR is copied into the CIR.

5. The instruction/data held in the CIR is ​ (e)   and then executed. Results of processing are stored in the ACC.

6. The cycle then returns to step one.

• program counter
• MAR
• address bus
• decoded
• MDR
• ALU
• fetched

The clock sends out a regular electrical pulse which synchronises (keeps in time) all the components.

The frequency of the pulses is known as the clock speed. Clock speed is measured in hertz. The higher the frequency, the more ______ can be performed in any given moment of time.