COMPUTER SCIENCE AND ENGINEERING
COMPUTER ARCHITECTURE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Fetch instruction from control unit to memory
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Fetch instruction from memory to control unit
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Fetch instruction from control unit to arithmetic logic unit
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None of the above
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Detailed explanation-1: -The CPU is designed to understand a set of instructions-the instruction set. 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.
Detailed explanation-2: -Fetch – The control unit requests instructions from the main memory that is stored at a memory’s location as indicated by the program counter (also known as the instruction counter). Decode – Received instructions are decoded in the instruction register.
Detailed explanation-3: -The Control Unit sends a signal to the RAM in order to fetch the program and data, which is then stored in one of the CPU’s register. To do so, the CPU makes use of a vital hardware path called the ‘address bus’ along which the program and data travels. The Control Unit then increments the Program Counter (PC).
Detailed explanation-4: -The control unit fetches (gets) the instruction from memory. The control unit decodes the instruction (decides what it means) and directs that the necessary data be moved from memory to the arithmetic/logic unit. These first two steps together are called instruction time, or I-time.