SSC IMD SA 2017 – Question 113

Which of the following statements is true?

• ROM is a read/write memory.
• PC points to the last instruction that was executed.
• Stack works on the principle of LIFO.
• All instructions affect flags.

Detailed Explanation:

The correct answer is c) Stack works on the principle of LIFO. (स्टैक LIFO के सिद्धांत पर काम करता है।).

Evaluation of Statements:

• Statement c is TRUE: A Stack is a linear data structure operating strictly on the LIFO (Last In, First Out) or FILO (First In, Last Out) principle. The element that is pushed (inserted) most recently at the top of the stack is always the first one to be popped (removed).
• Statement a is FALSE: ROM stands for Read-Only Memory; it is non-volatile memory that cannot be freely modified during normal computer operation (RAM is read/write memory).
• Statement b is FALSE: The Program Counter (PC) points to the next instruction to be fetched and executed, not the instruction that was just completed.
• Statement d is FALSE: Not all instructions affect status flags. Data transfer instructions (e.g., MOV in 8085/x86), unconditional jumps (JMP), and NOP do not alter processor flags.