MCQ IN COMPUTER SCIENCE & ENGINEERING

Detailed explanation-1: -The control unit sends out a memory read signal, and the contents of the address 0000 are copied through the data bus to the memory data register (MDR). As the data fetched during the fetch stage is an instruction, it is copied into the instruction register (IR).

Detailed explanation-2: -The CPU then takes the instruction at the memory address described by the MAR and copies it into the memory data register (MDR). The MDR also acts as a two-way register that holds data fetched from memory or data waiting to be stored in memory (it is also known as the memory buffer register (MBR) because of this).

Detailed explanation-3: -A memory buffer register (MBR) or memory data register (MDR) is the register in a computer’s CPU that stores the data being transferred to and from the immediate access storage. It contains a copy of the value in the memory location specified by the memory address register.

Detailed explanation-4: -The memory buffer register is used to store information and data that can be read or written in the computer memory. The main function of the memory buffer register is to store various types of computer instructions and data that can be transferred between computer memory.

Detailed explanation-5: -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.