Which of the following is INCORRECT about an instruction Pipeline?

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It increases the throughput of the computer system.
It is useful for performing floating point operations.
It lets a stream of instructions to execute by overlapping fetch, decode and execute phases of an instruction cycle.
It reads instruction from memory while previous instructions are being executed in other segments of the pipeline.

Answer 1

The correct answer is Option 2) It is useful for performing floating point operations.

Key Points

Instruction pipelining is a technique used in CPUs to improve instruction throughput by overlapping different stages (Fetch, Decode, Execute, etc.) of multiple instructions.
It is mainly used for general instruction execution, not specifically for floating point operations, which are handled separately in the floating point unit (FPU).
Floating point operations often involve more complex logic and longer latency; hence, they require specialized handling, not the standard instruction pipeline.
This makes option 2 incorrect, as it misrepresents the primary purpose of instruction pipelining.

Additional Information

Option 1 – Correct: Pipelining increases the throughput by allowing multiple instructions to be processed simultaneously at different stages.
Option 3 – Correct: It enables overlapping of fetch, decode, and execute cycles — thus improving instruction flow.
Option 4 – Correct: Pipelining allows the system to fetch new instructions from memory while previous ones are still being executed, utilizing different CPU segments concurrently.
Common Pipeline Stages:
- Instruction Fetch (IF)
- Instruction Decode (ID)
- Execute (EX)
- Memory Access (MEM)
- Write Back (WB)
Limitation: Pipelining does not eliminate data hazards, control hazards, or structural hazards — these must be managed via techniques like forwarding, stalls, and branch prediction.