Project ForgeConsider the following sequence of micro-operations.
MBR ← PC MAR ← X PC ← Y Memory ← MBR
Which one of the following is a possible operation performed by this sequence?
- AInstruction fetch
- BOperand fetch
- CConditional branch
- Initiation of interrupt service
Explanation
The sequence saves the current PC (the return address) into MBR, sets MAR to a fixed location X, unconditionally changes PC to Y (the handler address), and stores the saved PC into memory at address X. Saving the return address to a fixed location and jumping unconditionally to a handler is exactly what happens when an interrupt service routine is initiated — not a fetch (which wouldn't change PC to an unrelated Y) or a conditional branch (PC changes unconditionally here).
Source: GATE CS 2013 (2013)
This question is part of a 15-day revision cycle — sign in and Project Forge will bring it back the day before you'd forget it.