Computer Organization Questions and Answers – Interrupts – 1

This set of Computer Organization and Architecture Multiple Choice Questions & Answers (MCQs) focuses on “Interrupts – 1”.

1. The interrupt-request line is a part of the ___________
a) Data line
b) Control line
c) Address line
d) None of the mentioned
View Answer

Answer: b
Explanation: The Interrupt-request line is a control line along which the device is allowed to send the interrupt signal.

2. The return address from the interrupt-service routine is stored on the ___________
a) System heap
b) Processor register
c) Processor stack
d) Memory
View Answer

Answer: c
Explanation: The Processor after servicing the interrupts as to load the address of the previous process and this address is stored in the stack.

3. The signal sent to the device from the processor to the device after receiving an interrupt is ___________
a) Interrupt-acknowledge
b) Return signal
c) Service signal
d) Permission signal
View Answer

Answer: a
Explanation: The Processor upon receiving the interrupt should let the device know that its request is received.

4. When the process is returned after an interrupt service ______ should be loaded again.
i) Register contents
ii) Condition codes
iii) Stack contents
iv) Return addresses
a) i, iv
b) ii, iii and iv
c) iii, iv
d) i, ii
View Answer

Answer: d
Explanation: None.

5. The time between the receiver of an interrupt and its service is ______
a) Interrupt delay
b) Interrupt latency
c) Cycle time
d) Switching time
View Answer

Answer: b
Explanation: The delay in servicing of an interrupt happens due to the time is taken for contact switch to take place.
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6. Interrupts form an important part of _____ systems.
a) Batch processing
b) Multitasking
c) Real-time processing
d) Multi-user
View Answer

Answer: c
Explanation: This forms an important part of the Real time system since if a process arrives with greater priority then it raises an interrupt and the other process is stopped and the interrupt will be serviced.

7. A single Interrupt line can be used to service n different devices.
a) True
b) False
View Answer

Answer: a
Explanation: None.

8. ______ type circuits are generally used for interrupt service lines.
i) open-collector
ii) open-drain
iii) XOR
iv) XNOR
a) i, ii
b) ii
c) ii, iii
d) ii, iv
View Answer

Answer: a
Explanation: None.

9. The resistor which is attached to the service line is called _____
a) Push-down resistor
b) Pull-up resistor
c) Break down resistor
d) Line resistor
View Answer

Answer: b
Explanation: This resistor is used to pull up the voltage of the interrupt service line.

10. An interrupt that can be temporarily ignored is ___________
a) Vectored interrupt
b) Non-maskable interrupt
c) Maskable interrupt
d) High priority interrupt
View Answer

Answer: c
Explanation: The maskable interrupts are usually low priority interrupts which can be ignored if a higher priority process is being executed.

11. The 8085 microprocessor responds to the presence of an interrupt ___________
a) As soon as the trap pin becomes ‘LOW’
b) By checking the trap pin for ‘high’ status at the end of each instruction fetch
c) By checking the trap pin for ‘high’ status at the end of execution of each instruction
d) By checking the trap pin for ‘high’ status at regular intervals
View Answer

Answer: c
Explanation: The 8085 microprocessor are designed to complete the execution of the current instruction and then to service the interrupts.

12. CPU as two modes privileged and non-privileged. In order to change the mode from privileged to non-privileged.
a) A hardware interrupt is needed
b) A software interrupt is needed
c) Either hardware or software interrupt is needed
d) A non-privileged instruction (which does not generate an interrupt)is needed
View Answer

Answer: b
Explanation: A software interrupt by some program which needs some CPU service, at that time the two modes can be interchanged.

13. Which interrupt is unmaskable?
a) RST 5.5
b) RST 7.5
d) Both RST 5.5 and 7.5
View Answer

Answer: c
Explanation: The trap is a non-maskable interrupt as it deals with the ongoing process in the processor. The trap is initiated by the process being executed due to lack of data required for its completion. Hence trap is unmaskable.

14. From amongst the following given scenarios determine the right one to justify interrupt mode of data transfer.
i) Bulk transfer of several kilo-byte
ii) Moderately large data transfer of more than 1kb
iii) Short events like mouse action
iv) Keyboard inputs
a) i and ii
b) ii
c) i, ii and iv
d) iv
View Answer

Answer: d
Explanation: None.

15. How can the processor ignore other interrupts when it is servicing one ___________
a) By turning off the interrupt request line
b) By disabling the devices from sending the interrupts
c) BY using edge-triggered request lines
d) All of the mentioned
View Answer

Answer: d
Explanation: None.

Sanfoundry Global Education & Learning Series – Computer Organization and Architecture.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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