GATE | GATE-CS-2007 | Question 73

Consider the data given in above questions. Assume that the memory is byte addressable and the word size is 32 bits. If an interrupt occurs during the execution of the instruction “INC R3”, what return address will be pushed on to the stack?
(A) 1005
(B) 1020
(C) 1024
(D) 1040

Answer: (C)

Explanation: Explanation:

If memory is byte addressable so for each instruction it requires 1 word that is equal to 4 bytes which require 4 addresses

Instruction Word location
MOV R1,3000 2 1000-1007
MOV R2,R1 1 1008-1011
ADD R2,R1 1 1012-1015
MOV(R3),R2 1 1016-1019
INC R3 1 1020-1023
DEC R1 1 1024-1027

Interrupt occur during execution of instruction INC R3. So CPU will complete the execution of this instruction and push the next address 1024 in the stack. So after interrupt service program can be resumed for next instruction.

So (C) is correct option.

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