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8051 Ports Interfacing MCQ Questions & Answers

8051 Ports Interfacing MCQs : This section focuses on the "8051 Ports Interfacing". These Multiple Choice Questions (MCQs) should be practiced to improve the 8051 Ports Interfacing skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

Question 1

After the display is selected by second port, then the digit (LED) glows for a duration of

A. 5 msec
B. 10 msec
C. 2 msec
D. 6 msec

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Question 2

Each port line of a port can individually sink a current of upto

A. 2 mA
B. 8 mA
C. 5 mA
D. 1 mA

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Question 3

Each port line of a port can individually source a current of upto

A. 0.2 mA
B. 0.25 mA
C. 0.5 mA
D. 0.75 mA

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Question 4

For deriving chip selects of isolated memory or IO devices, the gates that are traditionally used are

C. NOT and NOR
D. AND, OR and NOT

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Question 5

If EA(active low) signal =1, then the execution starts from

A. internal EPROM
B. flash RAM
C. internal EPROM or flash RAM
D. none

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Question 6

If the EA(active low) signal is grounded then the execution

A. directly start from main memory
B. directly start from 16 bit address in main memory
C. directly start from 16 bit address in program memory
D. directly start from RAM

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Question 7

Port 1 lines are used during programming of

A. external EPROM and EEPROM
B. external ROM and RAM
C. internal ROM and RAM
D. internal EPROM and EEPROM

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Question 8

The configuration in which each LED receives operating current of 8 mA from power supply while the port lines sink the current on each port line is

A. common port configuration
B. common anode configuration
C. common cathode configuration
D. none of the mentioned

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Question 9

The device that is used for deriving chip select signals is

A. Logic gates
B. Multiplexers
C. PLAs and EPROMs
D. All of the mentioned

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Question 10

The maximum current that can be sinked totally by all the ports of 8051 is

A. 61 mA
B. 81 mA
C. 91 mA
D. 71 mA

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Question 11

The number of LEDs that can be connected to a port of 8051, if all are expected to glow simultaneously is

A. 6
B. 8
C. 10
D. 12

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Question 12

The number of scans of the complete 8-digit display that can be carried out in one second is

A. 15
B. 25
C. 35
D. 55

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Question 13

The number of TTL inputs that can be sinked by the port 0 when a logic 0 is sent to a port line as an output port is

A. 2
B. 4
C. 6
D. 8

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Question 14

The open drain bidirectional (input or output) port with internal pullups is

A. Port 0
B. Port 1
C. Port 2
D. Port 3

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Question 15

The pin that is grounded for interfacing external EPROM is

A. EA(active low)
B. PSEN(active low)
C. OE(active low)
D. All of the mentioned

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Question 16

The port that can source or sink 4 LS TTL inputs when being used as an output port on each of its line is

A. Port 1
B. Port 2
C. Port 3
D. all of the mentioned

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Question 17

The port that will source a current of 500 micro amperes when being used as input ports is

A. 0.5 mA
B. 0.25 mA
C. 250 micro amperes
D. 500 micro amperes

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Question 18

The step that is involved in the procedure of memory interfacing with 8051 is

A. data bus is connected to data lines of memory chips
B. PSEN(active low) is connected to OE(active low) of EPROM chips
C. writing address map of memory chip in bit form
D. all of the mentioned

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Question 19

To convert its current output into a voltage, the DAC 0808 is connected with

A. Transistor(BJT) externally
B. FET externally
C. OPAMP externally
D. OPAMP internally

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Question 20

When the port lines of a port are to be used as input lines then the value that must be written to the port address is

A. F0H
B. 0FH
D. 00H

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Question 21

Which of the following is not one of the SFR addresses of the ports of 8051?

A. 80H
B. 90H
C. A0H

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Question 22

Which is true in interfacing 7 segment code display?

A. transmitted by second port
B. display is selected by third port
C. display is selected by second port
D. none of the mentioned

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