Computer Organization Questions and Answers – Accessing I/O Devices

This set of Computer Organization and Architecture Multiple Choice Questions & Answers (MCQs) focuses on “Accessing I/O Devices”.

1. In memory-mapped I/O ____________
a) The I/O devices and the memory share the same address space
b) The I/O devices have a separate address space
c) The memory and I/O devices have an associated address space
d) A part of the memory is specifically set aside for the I/O operation
View Answer

Answer: a
Explanation: Its the different modes of accessing the i/o devices.

2. The usual BUS structure used to connect the I/O devices is ___________
a) Star BUS structure
b) Multiple BUS structure
c) Single BUS structure
d) Node to Node BUS structure
View Answer

Answer: c
Explanation: BUS is a collection of address, control and data lines used to connect the various devices of the computer.

3. In intel’s IA-32 architecture there is a separate 16 bit address space for the I/O devices.
a) False
b) True
View Answer

Answer: b
Explanation: This type of access is called as I/O mapped devices.
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4. The advantage of I/O mapped devices to memory mapped is ___________
a) The former offers faster transfer of data
b) The devices connected using I/O mapping have a bigger buffer space
c) The devices have to deal with fewer address lines
d) No advantage as such
View Answer

Answer: c
Explanation: Since the I/O mapped devices have a separate address space the address lines are limited by the amount of the space allocated.

5. The system is notified of a read or write operation by ___________
a) Appending an extra bit of the address
b) Enabling the read or write bits of the devices
c) Raising an appropriate interrupt signal
d) Sending a special signal along the BUS
View Answer

Answer: d
Explanation: It is necessary for the processor to send a signal intimating the request as either read or write.

6. To overcome the lag in the operating speeds of the I/O device and the processor we use ___________
a) BUffer spaces
b) Status flags
c) Interrupt signals
d) Exceptions
View Answer

Answer: b
Explanation: The processor operating is much faster than that of the I/O devices, so by using the status flags the processor need not wait till the I/O operation is done. It can continue with its work until the status flag is set.

7. The method of accessing the I/O devices by repeatedly checking the status flags is ___________
a) Program-controlled I/O
b) Memory-mapped I/O
c) I/O mapped
d) None of the mentioned
View Answer

Answer: a
Explanation: In this method, the processor constantly checks the status flags, and when it finds that the flag is set it performs the appropriate operation.
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8. The method of synchronising the processor with the I/O device in which the device sends a signal when it is ready is?
a) Exceptions
b) Signal handling
c) Interrupts
d) DMA
View Answer

Answer: c
Explanation: This is a method of accessing the I/O devices which gives the complete power to the devices, enabling them to intimate the processor when they’re ready for transfer.

9. The method which offers higher speeds of I/O transfers is ___________
a) Interrupts
b) Memory mapping
c) Program-controlled I/O
d) DMA
View Answer

Answer: d
Explanation: In DMA the I/O devices are directly allowed to interact with the memory without the intervention of the processor and the transfers take place in the form of blocks increasing the speed of operation.
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10. The process wherein the processor constantly checks the status flags is called as ___________
a) Polling
b) Inspection
c) Reviewing
d) Echoing
View Answer

Answer: a
Explanation: None.

Sanfoundry Global Education & Learning Series – Computer Organization and Architecture.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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