More about Control Unit & Processor Architectures

How control unit controls the execution of instruction

- There are two types of how the Control Unit is designed.

- RISC is a hardwired method and ARM CPU uses this method.

- CISC is a micro-programmed method and Intel CPU uses this method.

- A micro-instruction is a set of micro-orders, and each each bit are connected to the components within the CPU with the internal bus. Each bit decides whether to read/write for the each components within the CPU.

 

 

 

Processor Architecture (focusing on ALU)

- ALU has a control signal connected to Control unit, and has two input registers and one output register.

 

ALU Block Diagram

 

- Overall the Computer System is consisted of Processing Unit, and Memory System. This is the minimum requirement of the Von Neumann Machine.

- Processing Unit is again consisted of Control unit and Datapath.

- Control Unit is a Finite State Machine, which gets machine instruction and datapath condition as inputs, and register transfer control signals(micro-orders) as outputs.

- Datapath are functional units(ALU, Multipliers, Dividers) and registers(PC, Shifters, SR).