Question

Match List - I with List - II. 

List - I		List - II
A.	Pipeline bubble	I.	A deliberate delay or idle slot inserted in pipeline
B.	Pipeline flush	II.	Clearing all in-progress instructions
C.	Data forwarding	III.	Using result before it is written back
D.	Pipeline stall	IV.	Holding stages due to dependency or resource conflict

Choose the correct answer from the options given below:

• A. A-I, B-II, C-III, D-IV
• B. A-II, B-I, C-III, D-IV
• C. A-IV, B-I, C-II, D-III
• D. A-IV, B-III, C-II, D-I

Hint:

Bubble = NOP (Idle). Flush = Reset (Branch taken). Forwarding = Shortcut (Bypass). Stall = Wait (Conflict).

Answer 1

The Correct Option is A

This matching concerns hazards and optimization techniques in CPU pipelining. 1. Pipeline Bubble (A-I): A bubble is an idle cycle (NOP - No Operation) inserted into the pipeline to prevent a hazard. It is a deliberate delay or idle slot. 2. Pipeline Flush (B-II): Occurs when a branch is taken and the instructions already in the pipeline are no longer valid. The pipeline must be cleared of all in-progress instructions to start fresh at the new branch target. 3. Data Forwarding (C-III): Also called bypassing. It allows the result of an ALU operation to be sent directly to the next instruction's input, using the result before it is written back to the register file. 4. Pipeline Stall (D-IV): A stall is the holding of stages in the pipeline because a required resource is busy or a data dependency has not yet been resolved.