# Recent questions tagged interrupts

1
External Interrupt may not arise because of illegal or erroneous use of an instruction. a timing device. external source. I/O devices.
2
Which of the following is false? Interrupts which are initiated by an instruction are software interrupts When a subroutine is called, the address of the instruction following the CALL instruction is stored in the stack pointer A micro program which is written as $0$’s and $1$’s is a binary micro program None of the options
3
Which of the following is an interrupt according to temporal relationship with system clock? Maskable interrupt Periodic interrupt Division by zero Synchronous interrupt
4
Consider the following statements. Daisy chaining is used to assign priorities in attending interrupts. When a device raises a vectored interrupt, the CPU does polling to identify the source of interrupt. In polling, the CPU periodically checks the status bits to know if any device needs its ... same time. Which of the above statements is/are TRUE? Ⅰ and Ⅱ only Ⅰ and Ⅳ only Ⅰ and Ⅲ only Ⅲ only
1 vote
5
The clock interrupt handler on a certain computer requires $2\: msec$ (including process switching overhead) per clock tick. The clock runs at $60\: Hz.$ What fraction of the CPU is devoted to the clock?
6
A computer has a three-stage pipeline as shown in Fig. 1-7(a). On each clock cycle, one new instruction is fetched from memory at the address pointed to by the PC and put into the pipeline and the PC advanced. Each instruction occupies exactly ... stage and the first instruction of the interrupt handler is fetched into the pipeline. Does this machine have precise interrupts? Defend your answer.
1 vote
7
In Fig. 5-9(b), the interrupt is not acknowledged until after the next character has been output to the printer. Could it have equally well been acknowledged right at the start of the interrupt service procedure? If so, give one reason for doing it at the end, as in the text. If not, why not?
8
CPU architects know that operating system writers hate imprecise interrupts. One way to please the OS folks is for the CPU to stop issuing new instructions when an interrupt is signaled, but allow all the instructions currently being executed to finish, then force the interrupt. Does this approach have any disadvantages? Explain your answer.
1 vote
9
Suppose that a computer can read or write a memory word in $5 nsec.$ Also suppose that when an interrupt occurs, all $32$ CPU registers, plus the program counter and PSW are pushed onto the stack. What is the maximum number of interrupts per second this machine can process?
10
Explain the tradeoffs between precise and imprecise interrupts on a superscalar machine.
11
How could an operating system that can disable interrupts implement semaphores?
12
Suppose that an operating system does not have anything like the select system call to see in advance if it is safe to read from a file, pipe, or device, but it does allow alarm clocks to be set that interrupt blocked system calls. Is it possible to implement a threads package in user space under these conditions? Discuss.
13
Consider a system in which threads are implemented entirely in user space, with the run-time system getting a clock interrupt once a second. Suppose that a clock interrupt occurs while some thread is executing in the run-time system. What problem might occur? Can you suggest a way to solve it?
14
Can a thread ever be preempted by a clock interrupt? If so, under what circumstances? If not, why not?
15
Why would a thread ever voluntarily give up the CPU by calling thread yield? After all, since there is no periodic clock interrupt, it may never get the CPU back.
16
On all current computers, at least part of the interrupt handlers are written in assembly language. Why?
17
Suppose that you were to design an advanced computer architecture that did process switching in hardware, instead of having interrupts. What information would the CPU need? Describe how the hardware process switching might work.
18
When a user program makes a system call to read or write a disk file, it provides an indication of which file it wants, a pointer to the data buffer, and the count. Control is then transferred to the operating system, which calls the appropriate driver. Suppose that ... no data for it). What about the case of writing to the disk? Need the caller be blocked awaiting completion of the disk transfer?
19
Consider a process P1 that is executing on a Linux-like OS on a single core system. When P1 is executing, a disk interrupt occurs, causing P1 to go to kernel mode to service that interrupt. The interrupt delivers all the disk blocks that unblock a process P2 (which blocked earlier ... is ready and P2 is ready P1 is ready and P2 is running P1 is running and P2 is ready P1 is blocked and P2 is ready
1 vote
20
True/false 1. To access bus the DMA does not issue an interrupt it is done through DMA-request and DMA-acknowledge wires. Interrupt is issued by DMA to CPU only after complete data is transferred to the specific memory address by DMA. 2. DMA interrupts the CPU whenever it needs to initiate I/O and also when it has finished I/O transfers.
1 vote
21
I think percentage of processor time consumed should be $\frac{ \,ISR\,time}{ISR\,time+\,Data\,Transfer\,Time}=\frac{100}{100+122}$. Is it correct?
1 vote
22
In this state diagram of interrupt, where interrupt service routine is used? Why both hardware and software control are needed to service an interrupt? PC,PSW and ISR how it execute one after another, I just getting problem which is the order of coming these to process interrupt and why?(Any easy discussion on this)
23
24
When an interrupt occurs, an operating system can ignore the interrupt? Please tell the answer with reasoning? Thank you!
25
https://gateoverflow.in/1657/gate1998-1-20 https://gateoverflow.in/1300/gate2009-8-ugcnet-june2012-iii-58 The answer assumes execution means the execute phase in a pipelined system while in the other answer, execution means the execution of an entire instruction. How to know when to assume what? Option C is considered as wrong in the first link while it is the correct answer in the second link.
1 vote