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06 - Interrupts and ISR in the FDE

 1. We, as humans, are interrupted all the time. If someone pokes us, we stop what we're doing. Similarly, an interrupt is…

  All of the above are valid statements

  a signal sent from hardware (and also from software) to the CPU

  a request for attention for CPU time

  a signal that make the OS aware of an issue so it can decide what course of action to take.

 2. Group #1 in this list provides examples of: 
#1==================
Reset Button pressed
Power Supply failure
Power-down command (screen off, hibernate etc)
These send a physical signal to the CPU via the interrupt chip.

#2==================
Software is also allowed to issue interrupts to the CPU. 
For example software has detected that an error has occurred and 
will issue a software interrupt for the CPU to run some instructions
 to try to clear the error. 

#3==================
Some programs trigger a 'timer interrupt' for example a data-logging 
application that *has* to read an input sensor every 1 second.
Or perhaps a screen recording application that has to read the next 
screen update.

#4==================
Devices such as the keyboard and mouse – key presses, movements, 
clicks etc. Other Input - Output devices include
Hard Disk – Request to read or write data
Optical Disk
Printer
Graphics tablet

  Hardware commands /interrupts

  Program/Software interrupts

  Input / Output Device interrupts

  Timer interrupts

 3. Group #2 in this list provides examples of: 
#1==================
Reset Button pressed
Power Supply failure
Power-down command (screen off, hibernate etc)
These send a physical signal to the CPU via the interrupt chip.

#2==================
Software is also allowed to issue interrupts to the CPU. 
For example software has detected that an error has occurred and 
will issue a software interrupt for the CPU to run some instructions
 to try to clear the error. 

#3==================
Some programs trigger a 'timer interrupt' for example a data-logging 
application that *has* to read an input sensor every 1 second.
Or perhaps a screen recording application that has to read the next 
screen update.

#4==================
Devices such as the keyboard and mouse – key presses, movements, 
clicks etc. Other Input - Output devices include
Hard Disk – Request to read or write data
Optical Disk
Printer
Graphics tablet

  Program/Software interrupts

  Input / Output Device interrupts

  Timer interrupts

  Hardware commands /interrupts

 4. Group #3 in this list provides examples of: 
#1==================
Reset Button pressed
Power Supply failure
Power-down command (screen off, hibernate etc)
These send a physical signal to the CPU via the interrupt chip.

#2==================
Software is also allowed to issue interrupts to the CPU. 
For example software has detected that an error has occurred and 
will issue a software interrupt for the CPU to run some instructions
 to try to clear the error. 

#3==================
Some programs trigger a 'timer interrupt' for example a data-logging 
application that *has* to read an input sensor every 1 second.
Or perhaps a screen recording application that has to read the next 
screen update.

#4==================
Devices such as the keyboard and mouse – key presses, movements, 
clicks etc. Other Input - Output devices include
Hard Disk – Request to read or write data
Optical Disk
Printer
Graphics tablet

  Timer interrupts

  Hardware commands /interrupts

  Input / Output Device interrupts

  Program/Software interrupts

 5. Group #4 in this list provides examples of: 
#1==================
Reset Button pressed
Power Supply failure
Power-down command (screen off, hibernate etc)
These send a physical signal to the CPU via the interrupt chip.

#2==================
Software is also allowed to issue interrupts to the CPU. 
For example software has detected that an error has occurred and 
will issue a software interrupt for the CPU to run some instructions
 to try to clear the error. 

#3==================
Some programs trigger a 'timer interrupt' for example a data-logging 
application that *has* to read an input sensor every 1 second.
Or perhaps a screen recording application that has to read the next 
screen update.

#4==================
Devices such as the keyboard and mouse – key presses, movements, 
clicks etc. Other Input - Output devices include
Hard Disk – Request to read or write data
Optical Disk
Printer
Graphics tablet

  Input / Output Device interrupts

  Hardware commands /interrupts

  Timer interrupts

  Program/Software interrupts

 6. When an interrupt occurs, a ___________________or, in the case of a software interrupt, a flag is set.

  signal is sent to the CPU via a control bus

  None of the above

  power off button is switched off

  signal is sent directly to the operating system via the RAM

 7. After the interrupt signal has been sent,

  None of the above

  A special register, known as the program counter, is updated by setting it to zero

  A special register, held in the RAM, is updated and then switches off the machine

  A special register, known as the interrupt register, is then updated by flipping a bit to 1.

 8. It is the job of the CPU and not of the OS to decide WHICH interrupt will be handled 
Note: This question is asked because it is possible to register more than one interrupt at once.

  FALSE

  TRUE

 9. The OS can chose to ignore interrupts and this is called 'masking'

  TRUE

  FALSE

 10. Keyboard interrupts can be postponed without too much worry where as interrupts such as hardware power off …

  None of the above

  must be dealt with immediately

  must be completely ignored

  must be put to the back of the list

 11. When an interrupt occurs, the CPU has the role of informing the OS rather than dealing with the interrupt itself.

  TRUE

  FALSE

 12. Hardware and software can trigger interrupts and these are then dealt with by calling an
ISR.png

  internet service provider

  interrupt sentdex register

  interrupt service routine

  interrupt sent roster

 13. A multitasking operating system can run more than one process. Interrupts are used to allow the process to continue

  FALSE

  TRUE

 14. When an interrupt is received, a program called an _____ will run

  vector routine

  RAM counter

  Interrupt Service Routine (ISR)

  program counter driver

 15. The ISR is held in _______________ to indicate the item in the stack to be executed next.

  queue memory that uses a RAM slot

  queue memory that uses a pointer

  stack memory that uses an operating system with a program counter

  stack memory that uses a pointer

 16. Some processes involve a delay, for example printing a document: the computer can send the data faster than the printer can process it. Fill in the blanks 
A small area of memory called a _____allows printing to appear continuous. As the buffer empties, an interrupt is sent for more data to be sent.

  interrupt routine provider

  buffer

  ROM chip

  program counter

 17. …………………….are used to indicate when an interrupt has occurred

  flags

  interrupt routine provider

  ROM chip

  buffer

 18. Interrupts use ……………... to indicate that a process is more critical so should be handled first

  program counters

  buffers

  flags

  priorities

 19. When an interrupt is processed the following needs to happen

  3 - Restore the processor state

  All of the listed options (1,2,3) need to happen in the specified order (i.e 1,2,3)

  2 - Execute the ISR

  1 - Save the processor state

 20. It is possible for interrupts to be interrupted by interrupts.

  TRUE

  FALSE


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