This set of Microprocessor Multiple Choice Questions & Answers (MCQs) focuses on “Special Operations”.
1. Which of the following operation is not carried out by 80286?
a) task switch operation
b) halt
c) processor reset
d) none of the mentioned
View Answer
Explanation: The 80286 carries out six operations. They are:
1. processor reset and initialization
2. task switch operation
3. pointer testing instructions
4. protected mode initialization
5. how to enter protected mode?
6. halt.
2. After completion of the first cycle, the first task is again scheduled for the next cycle. This process is known as
a) repetition
b) task switch operation
c) processor initiation
d) none of the mentioned
View Answer
Explanation: After completion of the first cycle, the first task is again scheduled for the next cycle, and the process continues. The previous task that was incomplete, may be completed during its coming turns of the allotted CPU time slice. This switch-over operation from one task to another is called task switch operation.
3. The operation that is provided by the internal architecture, to save the execution state of a task is
a) processor reset
b) processor initialization
c) task switch operation
d) halt
View Answer
Explanation: The 80286 internal architecture provides a task switch operation, to save the execution state of a task, and to load a new task to be executed.
4. The instruction that can be used to carry out task switch operation is
a) software interrupt instruction
b) exception
c) external interrupt
d) all of the mentioned
View Answer
Explanation: A software interrupt instruction, exception or external interrupt, can also be used to carry out task switch operation.
5. The IRET instruction gets back the execution state of the previous task, if
a) NT (nested task flag) = 1
b) NT (nested task flag) = 0
c) IF (interrupt flag) = 1
d) IF (interrupt flag) = 0
View Answer
Explanation: If NT = 1, the IRET instruction gets back the execution state of the previous task. Otherwise, the IRET instruction lets the current task continue, after popping the required values from the stack.
6. The NT flag is set by the task switch operation, that is initiated by
a) CALL
b) INT
c) CALL & INT
d) None of the mentioned
View Answer
Explanation: The NT flag is set by CALL or INT initiated task switch operations.
7. The 80286 executes LMSW instruction to enter into
a) real addressing mode
b) protected mode
c) real addressing and protected modes
d) none of the mentioned
View Answer
Explanation: To enter into protected mode, 80286 executes LMSW instruction, that sets PE flag.
8. The instruction that sets the zero flag, if the segment referred to, by the selector can be read is
a) VERW
b) VERR
c) LSL
d) LAR
View Answer
Explanation: The VERR (VERify to Read) instruction sets the zero flag, if the segment referred to, by the selector, can be read.
9. The instruction that sets the zero flag, if the segment referred to by the selector, can be written as
a) VERW
b) APRL
c) LSL
d) LAR
View Answer
Explanation: The VERW (VERify to Write) instruction sets the zero flag, if the segment referred to, by the selector can be written.
10. The instruction that reads the descriptor access rights byte into the register is
a) VERW
b) APRL
c) LSL
d) LAR
View Answer
Explanation: The LAR (Load Access Rights) instruction reads the descriptor access rights byte into the register, if privilege rules allow.
11. The instruction that reads the segment limit into the register, if privilege rules and descriptor type allow is
a) VERW
b) APRL
c) LSL
d) LAR
View Answer
Explanation: The LSL (Load Segment Limit) instruction reads the segment limit into the register, if privilege rules, and descriptor type allow.
12. The instruction that adjusts the RPL (Requested Privilege Level) of the selector, to the numeric maximum of current selector RPL value is
a) LAR
b) VERR
c) LSL
d) APRL
View Answer
Explanation: The APRL (Adjust Requested Privilege Level) adjusts the RPL (Requested Privilege Level) of the selector to the numeric maximum of current selector RPL value, and the RPL value in the register.
Sanfoundry Global Education & Learning Series – Microprocessors.
Here’s the list of Best Books in Microprocessors.
If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]
- Practice Electronics & Communication Engineering MCQs
- Check Computer Science Books
- Practice Computer Science MCQs
- Check Electronics & Communication Engineering Books
- Apply for Computer Science Internship
