NIMCET Central Processing Unit (CPU) Previous Year Questions (PYQs)
Study Stuff for MCA Examinations
Which of the following statements about the fetch-decode-execute cycle in a CPU are correct?
I. The Program Counter is incremented after each instruction is fetched so the CPU moves to the next instruction.
II. The Control Unit is responsible for fetching instructions and placing them in the Instruction Register.
III. The ALU is responsible for decoding instructions and determining which operation to perform.
IV. Registers are used to permanently store the operating system's files for fast access.
Identify the correct option.
Solution
Statement I is correct.
The Program Counter stores the address of the next instruction. After fetching an instruction, it is usually incremented so that the CPU can move to the next instruction.
Statement II is also correct.
The Control Unit controls the fetch-decode-execute cycle. It fetches instructions from memory and places them into the Instruction Register.
Statement III is incorrect.
The ALU performs arithmetic and logical operations. It does not decode instructions. Instruction decoding is handled by the Control Unit.
Statement IV is incorrect.
Registers are small, fast storage locations inside the CPU. They do not permanently store operating system files.
So, only statements I and II are correct.
Solution
Solution
✅ Memory Unit Communication with CPU:
The memory unit which directly communicates with the CPU is known as:
✅ Primary Memory:
Primary memory, also called Main Memory, includes components like RAM (Random Access Memory) and Cache Memory.
✅ Why Primary Memory?
Primary memory is directly accessible by the CPU, allowing it to fetch data and instructions quickly for processing.
✅ Final Answer:
The memory unit that directly communicates with the CPU is: Primary Memory or Main Memory
Solution
Solution
Time for Fetch & Execute
Definition:
The time required to fetch and execute one machine instruction is called a
Machine Cycle / CPU Cycle.
Includes:
- Instruction fetch
- Instruction decode
- Operand fetch (if any)
- Execution
- Result store (if any)
✅ Final Answer: Machine Cycle / CPU Cycle.
Solution
Which of the following does not affect CPU performance?
Answer: (c) Amount of RAM
Explanation:
CPU performance is determined by factors like:
- Number of cores – Enables parallel processing
- Cache size – Faster data access for the CPU
- Clock speed – Determines how fast instructions are executed
Note: While RAM is important for multitasking and running large applications, the CPU's raw performance depends on its own architecture and specifications.
Solution
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