Architecture of the CPU

What is the purpose of the CPU?

The role of the CPU is to process instructions by running fetch-decode-execute cycle

Describe the first stage of the Fetch-Execute-Cycle

-The Program counter holds the address of the next instruction. This address is transferred to the memory address register(MAR).. The instruction in MAR is transferred to the Memory Data Register(MDR).The PC is incremented so it points to the next instruction to be executed

Describe the second stage of fetch-execute-cycle

The control unit decodes the instruction to work out what needs to be done.

What happens at execute stage of fetch-decode-execute cycle

The instruction is carried out by Control unit . Any result is stored in the Accumulator(ACC) register.

Describe each component in CPU

1)Arithmetic Logic Unit(ALU):Performs calculations and logical decisions

2)Control Unit:Send signals to control how data moves around CPU

3)Cache:Provides fast access to frequently used instructions and data

4)Register:Tiny,super fast pieces of onboard memory inside the CPU

What is Von Neumann Architecture and what does it consist of?

-It’s based on the concept of the store program concept. Both instruction data and program data are stored in the same memory in binary form.Theres no way to know if the pure binary held in memory is representing instructions or data by looking at it

-Consistes of:

1)Control Unit(Cu)

2)Arithmetic and Logic Unit(ALU)

3)Memory Unit(Typically RAM)

4)Inputs and Outputs

Registers

Explain each Register in the Von Neumann Architecture

1)Program Counter(PC):Holds the address of the next instruction in memory

2)Memory Address Register(MAR):Holds the address of where data is to be fetched or stored

3)Memory Data Register(MDR):Holds the data fetched from, or to be written to memory

4)Accumulator:Holds the result of calculations

What’s the difference between storing data and address

-Storing a address of a location in MAR can only be read from or written to

-Storing data in MDR has been read or data that needs to be written