Question 1

In UNIX, part of a path name includes a device name.

Accepted Answer

A) True 
 B)False

Question 2

A maskable interrupt can never be disabled.

Accepted Answer

A) True 
 B)False

Question 3

Which of the following is TRUE about a serial port controller and a fibre channel (FC)  bus controller?

Accepted Answer

A)   Both FC bus controller and serial port controller are often implemented as separate circuit boards.
B)   A serial-port controller is a simple device controller, while an FC bus controller is complex.
C)   Both FC bus controller and serial port controller are used in PCs.
D)   All of the above.E) None of the above
F) A) and D)

Question 4

A control register in an I/O device control

Accepted Answer

A)   is written by the host to send output.
B)   is written by the host to choose half-duplex communication.
C)   is read by the host to get input.
D)   contains status bits that can be read by the host.E) A) and D)
F) All of the above

Question 5

Give an example of when an application may need a nonblocking I/O system call.

Accepted Answer

If the user is viewing a web browser, th...

Question 6

Which of the following is NOT a technique used for managing power consumption in mobile devices?

Accepted Answer

A)   Power collapse.
B)   chilling with natural sources such as lake water, and solar panels.
C)   Component level power management.
D)   Wakelocks.E) None of the above
F) B) and C)

Question 7

Interrupt chaining

Accepted Answer

A)   allows CPU to defer processing of low-priority interrupts without masking all interrupts.
B)   splits interrupt management between first level and second level interrupt handlers.
C)   is used to handle interrupts but not exceptions.
D)   is a compromise between the overhead of a huge interrupt table and the inefficiency of dispatching to a single interrupt handler.E) B) and D)
F) A) and C)

Question 8

Which of the following principles is used to improve the efficiency of I/O?

Accepted Answer

A)   Reduce the number of times that data must be copied in memory while passing between device and application.
B)   Move processing primitives into hardware, to allow their operation in device controllers to be concurrent with CPU and bus operation.
C)   Increase concurrency by using DMA-knowledgeable controllers or channels to offload simple data copying from the CPU.  
D)   All of the above.E) A) and B)
F) All of the above D

Question 9

In a blocking system call, the execution of a process is suspended

Accepted Answer

A)   until the process is woken up by some other process.
B)   until a fixed amount of time has elapsed.
C)   the kernel raises the priority of that process.
D)   the I/O has completed.E) None of the above
F) All of the above

Question 10

In DMA-based I/O,

Accepted Answer

A)   CPU is relieved from data transfer and is interrupted after every word has been transferred to initiate the next word transfer.
B)   cycle stealing can slow down the CPU computation, but off-loading the data-transfer work to a DMA controller generally improves the total system performance.
C)   interrupt mechanism is not used.
D)   data is transferred to/from a single block of memory, but not to/from multiple blocks.E) A) and B)
F) B) and C) B

Question 11

An expansion bus is used to connect relatively high speed devices to the main bus.

Accepted Answer

A) True 
 B)False

Question 12

Buffering in I/O is used to

Accepted Answer

A)   cope with a speed mismatch between the producer and consumer of a data stream.
B)   provide adaptations for devices that have different data-transfer sizes.
C)   support copy semantics for application I/O.
D)   All of the above.E) A) and C)
F) C) and D)

Question 13

Which of the following is FALSE about streams?

Accepted Answer

A)   A stream is a full-duplex connection between a device driver and a user-level process.
B)   Each stream module contains a pair of queues.
C)   The number of modules in a stream is fixed by the operating system.
D)   Messages may be dropped in a stream even if flow control is implemented.E) A) and C)
F) A) and D) C

Question 14

Technique used to improve I/O efficiency by temporarily storing copies of data is called

Accepted Answer

A)   spooling.
B)   buffering.
C)   caching.
D)   memory mapping.E) B) and C)
F) None of the above

Question 15

Explain the concept of a bus and daisy chain. Indicate how they are related.

Accepted Answer

A bus is merely a set of wires and a rig...

Question 16

Why is DMA used for devices that execute large transfers?

Accepted Answer

Without DMA, programmed I/O must be used...

Question 17

Explain the concept of polling between a host and a controller.

Accepted Answer

When a host tries to access th...

Question 18

What is the purpose of a UNIX mount table?

Accepted Answer

STREAMS enables an application to assemb...

Question 19

Component that measures elapsed time and to trigger operations is called a

Accepted Answer

A)   programmable interval timer.
B)   high performance event timer.
C)   network time protocol.
D)   socket.E) None of the above
F) B) and C)

Question 20

An I/O system call returns a one-bit information about the status of the call.

Accepted Answer

A) True 
 B)False

Exam 12: Io Systems

In UNIX, part of a path name includes a device name.

Correct AnswerverifiedShow Answer

A maskable interrupt can never be disabled.

Correct AnswerverifiedShow Answer

Which of the following is TRUE about a serial port controller and a fibre channel (FC) bus controller?

Correct AnswerverifiedShow Answer

A control register in an I/O device control

Correct AnswerverifiedShow Answer

Give an example of when an application may need a nonblocking I/O system call.

Correct AnswerverifiedIf the user is viewing a web browser, th...View AnswerShow Answer

Which of the following is NOT a technique used for managing power consumption in mobile devices?

Correct AnswerverifiedShow Answer

Interrupt chaining

Correct AnswerverifiedShow Answer

Which of the following principles is used to improve the efficiency of I/O?

Correct AnswerverifiedD

In a blocking system call, the execution of a process is suspended

Correct AnswerverifiedShow Answer

In DMA-based I/O,

Correct AnswerverifiedB

An expansion bus is used to connect relatively high speed devices to the main bus.

Correct AnswerverifiedShow Answer

Buffering in I/O is used to

Correct AnswerverifiedShow Answer

Which of the following is FALSE about streams?

Correct AnswerverifiedC

Technique used to improve I/O efficiency by temporarily storing copies of data is called

Correct AnswerverifiedShow Answer

Explain the concept of a bus and daisy chain. Indicate how they are related.

Correct AnswerverifiedA bus is merely a set of wires and a rig...View AnswerShow Answer

Why is DMA used for devices that execute large transfers?

Correct AnswerverifiedWithout DMA, programmed I/O must be used...View AnswerShow Answer

Explain the concept of polling between a host and a controller.

Correct AnswerverifiedWhen a host tries to access th...View AnswerShow Answer

What is the purpose of a UNIX mount table?

Correct AnswerverifiedSTREAMS enables an application to assemb...View AnswerShow Answer

Component that measures elapsed time and to trigger operations is called a

Correct AnswerverifiedShow Answer

An I/O system call returns a one-bit information about the status of the call.

Correct AnswerverifiedShow Answer

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If the user is viewing a web browser, th...
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D

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B

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C

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A bus is merely a set of wires and a rig...
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Without DMA, programmed I/O must be used...
View Answer

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When a host tries to access th...
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STREAMS enables an application to assemb...
View Answer

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