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1. The initial program that is run when the computer is powered up is called :
a. boot program
b. bootloader
c. initializer
d. bootstrap program
Answer: (d).bootstrap program

2. How does the software trigger an interrupt ?
a. Sending signals to CPU through bus
b. Executing a special operation called system call
c. Executing a special program called system program
d. Executing a special program calle interrupt trigger program
Answer: (b).Executing a special operation called system call

3. What is a trap/exception ?
a. hardware generated interrupt caused by an error
b. software generated interrupt caused by an error
c. user generated interrupt caused by an error
d. None of these
Answer: (b).software generated interrupt caused by an error

4. What is an ISR ?
a. Information Service Request
b. Interrupt Service Request
c. Interrupt Service Routine
d. Information Service Routine
Answer: (c).Interrupt Service Routine

5. An interrupt vector
a. is an address that is indexed to an interrupt handler
b. is a unique device number that is indexed by an address
c. is a unique identity given to an interrupt
d. None of these
Answer: (a).is an address that is indexed to an interrupt handler

6. DMA is used for :
a. High speed devices(disks and communications network)
b. Low speed devices
c. Saving CPU cycles
d. Both a and c
Answer: (d).Both a and c

7. In a memory mapped input/output :
a. the CPU uses polling to watch the control bit constantly, looping to see if device is ready
b. the CPU writes one data byte to the data register and sets a bit in control register to show that a byte is available
c. the CPU receives an interrupt when the device is ready for the next byte
d. the CPU runs a user written code and does accordingly
Answer: (b).the CPU writes one data byte to the data register and sets a bit in control register to show that a byte is available

8. In a programmed input/output(PIO) :
a. the CPU uses polling to watch the control bit constantly, looping to see if device is ready
b. the CPU writes one data byte to the data register and sets a bit in control register to show that a byte is available
c. the CPU receives an interrupt when the device is ready for the next byte
d. the CPU runs a user written code and does accordingly
Answer: (a).the CPU uses polling to watch the control bit constantly, looping to see if device is ready

9. In an interrupt driven input/output :
a. the CPU uses polling to watch the control bit constantly, looping to see if device is ready
b. the CPU writes one data byte to the data register and sets a bit in control register to show that a byte is available
c. the CPU receives an interrupt when the device is ready for the next byte
d. the CPU runs a user written code and does accordingly
Answer: (c).the CPU receives an interrupt when the device is ready for the next byte

10. In the layered approach of Operating Systems :
a. Bottom Layer(0) is the User interface
b. Highest Layer(N) is the User interface
c. Bottom Layer(0) is the hardware
d. Both b and c
Answer: (d).Both b and c

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