Processor Organization
To understand the organization of the CPU, let us consider the requirements placed on the CPU, the things that it must do:
* Fetch instruction: The CPU reads an instruction from memory.
* Interpret instruction: The instruction is decoded to determine what action is required.
* Fetch data: The execution of an instruction may require reading data from memory or an I/O module.
* Process data: The execution of an instruction may require performing some arithmetic or logical operation on data.
* Write data: The results of an execution may require writing data to memory or an I/O module.
To do these things, it should be clear that the CPU needs to store some data temporarily. It must remember the location of the last instruction so that it can know where to get the next instruction. It needs to store instructions and data temporarily while an instruction is being executed. In other words, the CPU needs a small internal memory.
Figure 1 is a simplified view of a CPU, indicating its connection to the rest of the system via the system bus. You will recall (Lecture 1) that the major components of the CPU are an arithmetic and logic unit (ALU) and a control unit (CU). The ALU does the actual computation or processing of data. The control unit controls the movement of data and instructions into and out of the CPU and controls the operation of the ALU. In addition, the figure shows a minimal internal memory, consisting of a set of storage locations, called registers.
To understand the organization of the CPU, let us consider the requirements placed on the CPU, the things that it must do:
* Fetch instruction: The CPU reads an instruction from memory.
* Interpret instruction: The instruction is decoded to determine what action is required.
* Fetch data: The execution of an instruction may require reading data from memory or an I/O module.
* Process data: The execution of an instruction may require performing some arithmetic or logical operation on data.
* Write data: The results of an execution may require writing data to memory or an I/O module.
To do these things, it should be clear that the CPU needs to store some data temporarily. It must remember the location of the last instruction so that it can know where to get the next instruction. It needs to store instructions and data temporarily while an instruction is being executed. In other words, the CPU needs a small internal memory.
Figure 1 is a simplified view of a CPU, indicating its connection to the rest of the system via the system bus. You will recall (Lecture 1) that the major components of the CPU are an arithmetic and logic unit (ALU) and a control unit (CU). The ALU does the actual computation or processing of data. The control unit controls the movement of data and instructions into and out of the CPU and controls the operation of the ALU. In addition, the figure shows a minimal internal memory, consisting of a set of storage locations, called registers.
Keep it up
ReplyDelete