Input Output interfacing Questions

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1.

 How many types of Interfacing?

A

2

B

3

C

4

D

5

Correct Answer: A

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2.

In which type of communication, the interface gets a single byte of data from the microprocessor and sends it bit by bit to the other system serially and vice-a-versa?

A

Parallel Communication Interface

B

Serial Communication Interface

C

Both A and B

D

None of the above

Correct Answer: B

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3.

Which of the following are known as Higher Address Bus?

A

A15 - A8

B

AD7 - AD0

C

READY

D

WR

Correct Answer: A

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4.

 In which mode, the CPU periodically reads an internal flag of 8279 to check whether any key is pressed or not with key pressure?

A

Interrupt mode

B

Polled mode

C

Decoded Mode

D

Encoded Mode

Correct Answer: B

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5.

 What is true about Encoded Mode?

A

the unit contains registers to store the keyboard, display modes

B

the counter internally decodes the least significant 2 bits and provides a decoded 1 out of 4 scan on SL0-SL3.

C

the processor is requested service only if any key is pressed, otherwise the CPU will continue with its main task.

D

the counter provides the binary count that is to be externally decoded to provide the scan lines for the keyboard and display.

Correct Answer: D

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6.

 Which pin is used to blank the display during digit switching?

A

WR

B

IR

C

BD

D

DB

Correct Answer: C

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7.

Which mode allows 8/16 character multiplexed displays to be organized as dual 4-bit/single 8-bit display units?

A

Display Entry

B

Display Scan

C

Strobed Input

D

Scanned Keyboard Mode

Correct Answer: B

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8.

DMA stands for?

A

Display Memory Access

B

Directly Memory Access

C

Device Memory Access

D

Direct Memory Access

Correct Answer: D

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9.

Which of the following is not true features of 8257?

A

It has three channels which can be used over three I/O devices.

B

Each channel has 16-bit address and 14-bit counter.

C

Each channel can transfer data up to 64kb.

D

Each channel can be programmed independently.

Correct Answer: A

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10.

What is correct range of frequency for 8257?

A

500Hz to 3MHz.

B

250Hz to 2MHz.

C

250Hz to 3MHz.

D

500Hz to 2MHz.

Correct Answer: C

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