MCQ IN COMPUTER SCIENCE & ENGINEERING

Detailed explanation-1: -The ‘instruction set’ of the CPU is designed to understand a specific set of commands, which serves to make sense of the instruction it has just fetched. This process is called ‘decode’.

Detailed explanation-2: -It fetches the instructions from the main memory and executes them. This is done repeatedly from when the computer is booted up to when it is shut down. The CPU fetches the instructions one at a time from the main memory into the registers. One register is the program counter (pc).

Detailed explanation-3: -During the decode stage, the control unit (CU) will decode the instruction in the CIR. The CU then sends signals to other components within the CPU, such as the arithmetic logic unit (ALU) and the floating point unit (FPU).

Detailed explanation-4: -The processor sends a signal along the address bus to the memory address held in the MAR. The instruction/data held in that memory address is sent along the data bus to the MBR/MDR . The instruction/data held in the MBR/MDR is copied into the CIR . The instruction/data held in the CIR is decoded and then executed.

Detailed explanation-5: -To execute an instruction, the processor copies the instruction code from the program memory into the instruction register (IR). It can then be decoded (interpreted) by the instruction decoder, which is a combinational logic block which sets up the processor control lines as required.