Microprocessor I/O Interfacing MCQ Questions

This section focuses on "I/O Interfacing" in Microprocessor. These Multiple Choice Questions (MCQ) should be practiced to improve the Microprocessor skills required for various interviews (campus interview, walk-in interview, company interview), placements, entrance exams and other competitive examinations.

1. How many types of Interfacing?

A. 2
B. 3
C. 4
D. 5

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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

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3. Which of the following are known as Higher Address Bus?

A. A15 - A8
B. AD7 - AD0

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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

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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.

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


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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

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8. DMA stands for?

A. Display Memory Access
B. Directly Memory Access
C. Device Memory Access
D. Direct Memory Access

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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.

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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.

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