250+ TOP MCQs on Interrupts and Interrupt Service Routines and Answers

Microprocessor Multiple Choice Questions on “Interrupts and Interrupt Service Routines”.

1. While CPU is executing a program, an interrupt exists then it
a) follows the next instruction in the program
b) jumps to instruction in other registers
c) breaks the normal sequence of execution of instructions
d) stops executing the program
Answer: c
Clarification: An interrupt function is to break the sequence of operation.

2. An interrupt breaks the execution of instructions and diverts its execution to
a) Interrupt service routine
b) Counter word register
c) Execution unit
d) control unit
Answer: a
Clarification: An interrupt transfers the control to interrupt service routine (ISR). After executing ISR, the control is transferred back again to the main program.

3. While executing the main program, if two or more interrupts occur, then the sequence of appearance of interrupts is called
a) multi-interrupt
b) nested interrupt
c) interrupt within interrupt
d) nested interrupt and interrupt within interrupt
Answer: d
Clarification: If an interrupt occurs while executing a program, and the processor is executing the interrupt, if one more interrupt occurs again, then it is called a nested interrupt.

4. Whenever a number of devices interrupt a CPU at a time, and if the processor is able to handle them properly, it is said to have
a) interrupt handling ability
b) interrupt processing ability
c) multiple interrupt processing ability
d) multiple interrupt executing ability
Answer: c
Clarification: The processor if handles more devices as interrupts then it has multiple interrupt processing ability.

5. NMI stands for
a) nonmaskable interrupt
b) nonmultiple interrupt
c) nonmovable interrupt
d) none of the mentioned
Answer: a
Clarification: NMI is the acronym for nonmaskable interrupt.

7. If any interrupt request given to an input pin cannot be disabled by any means then the input pin is called
a) maskable interrupt
b) nonmaskable interrupt
c) maskable interrupt and nonmaskable interrupt
d) none of the mentioned
Answer: b
Clarification: A nonmaskable interrupt input pin is one which means that any interrupt request at NMI (nonmaskable interrupt) input cannot be masked or disabled by any means.

8. The INTR interrupt may be
a) maskable
b) nonmaskable
c) maskable and nonmaskable
d) none of the mentioned
Answer: a
Clarification: the INTR (interrupt request) is maskable or can be disabled.

9. The Programmable interrupt controller is required to
a) handle one interrupt request
b) handle one or more interrupt requests at a time
c) handle one or more interrupt requests with a delay
d) handle no interrupt request
Answer: b
Clarification: If more than one interrupt request (INTR) occurs at a time, then an external chip called programmable interrupt controller is required to handle them.

10. The INTR interrupt may be masked using the flag
a) direction flag
b) overflow flag
c) interrupt flag
d) sign flag
Answer: c
Clarification: If a microprocessor wants to serve any interrupt then interrupt flag, IF=1. If interrupt flag, IF=0, then the processor ignores the service.