In 8086 A. The stack memory is a FIFO (First In First Out) B. The JMP instruction cannot be prefixed with segment override prefix C. SAHF and POPF instructions affect the flag register D. DAS instruction cannot be used for 8 bit operations. Choose the correct answer from the options given below :
B and C only
To solve this question, we need to understand each statement given and determine which are correct in the context of the 8086 microprocessor.
- A. The stack memory is a FIFO (First In First Out)
- This is incorrect. In 8086, stack memory operates on a LIFO (Last In First Out) basis. It means the last data pushed onto the stack is the first one to be popped out.
- B. The JMP instruction cannot be prefixed with segment override prefix
- This is correct. The JMP instruction in 8086 cannot be prefixed with a segment override prefix because a jump operation does not require a segment prefix, as it inherently knows the segment it needs to work with.
- C. SAHF and POPF instructions affect the flag register
- This is correct. The SAHF (Store AH into Flags) and POPF (Pop Flags) instructions directly affect the flag register.
- D. DAS instruction cannot be used for 8-bit operations
- This is incorrect. The DAS (Decimal Adjust after Subtraction) instruction in the 8086 is specifically used to adjust the result of an 8-bit subtraction into a packed BCD format, thus it is indeed used for 8-bit operations.
Consequently, the correct statement is B and C only. Therefore, the correct answer is \(B \text{ and } C \text{ only}\).
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