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
View Answer
Ans : A
Explanation: Interface is the path for communication between two components. Interfacing is of two types, memory interfacing and I/O interfacing.
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
View Answer
Ans : B
Explanation: Serial Communication Interface : In this 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.
3. Which of the following are known as Higher Address Bus?
A. A15 - A8
B. AD7 - AD0
C. READY
D. WR
View Answer
Ans : A
Explanation: A15 - A8 (Higher Address Bus)
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
View Answer
Ans : B
Explanation: In the Polled mode, the CPU periodically reads an internal flag of 8279 to check whether any key is pressed or not with key pressure.
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.
View Answer
Ans : D
Explanation: In the encoded mode, the counter provides the binary count that is to be externally decoded to provide the scan lines for the keyboard and display.
6. Which pin is used to blank the display during digit switching?
A. WR
B. IR
C. BD
D. DB
View Answer
Ans : C
Explanation: BD : It stands for blank display. It is used to blank the display during digit switching.
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
View Answer
Ans : B
Explanation: Display Scan : This mode allows 8/16 character multiplexed displays to be organized as dual 4-bit/single 8-bit display units.
8. DMA stands for?
A. Display Memory Access
B. Directly Memory Access
C. Device Memory Access
D. Direct Memory Access
View Answer
Ans : D
Explanation: DMA stands for Direct Memory Access
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.
View Answer
Ans : A
Explanation: It has four channels which can be used over four I/O devices is true.
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.
View Answer
Ans : C
Explanation: Its frequency ranges from 250Hz to 3MHz.
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