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The 8051 Microcontroller MCQ Questions & Answers

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




Question 1

The 8051 has ________ 16-bit counter/timers.

A. 1
B. 2
C. 3
D. 4

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Question 2

Data transfer from I/O to external data memory can only be done with the MOV command.

A. TRUE
B. FALSE

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Question 3

Which of the following commands will move the value at port 3 to register 2?

A. MOV P2, R3
B. MOV R3, P2
C. MOV 3P, R2
D. MOV R2, P3

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Question 4

An alternate function of port pin P3.4 in the 8051 is:

A. Timer 0
B. Timer 1
C. interrupt 0
D. interrupt 1

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Question 5

The contents of the accumulator after this operation MOV A,#0BH ANL A,#2CH will be

A. 11010111
B. 11011010
C. 1000
D. 101000

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Question 6

This program code will read data from port 0 and write it to port 2, and it will stop looping when bit 3 of port 2 is set: STAT: MOV A, PO  MOV P2,A  JNB P2.3, STAT

A. TRUE
B. FALSE

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Question 7

The number of data registers is:

A. 8
B. 16
C. 32
D. 64

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Question 8

Which of the following instructions will load the value 35H into the high byte of timer 0?

A. MOV TH0, #35H
B. MOV TH0, 35H
C. MOV T0, #35H
D. MOV T0, 35H

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Question 9

Device pins XTAL1 and XTAL2 for the 8051 are used for connections to an external oscillator or crystal.

A. TRUE
B. FALSE

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Question 10

Which of the following commands will copy the contents of location 4H to the accumulator?

A. MOV A, 04H
B. MOV A, L4
C. MOV L4, A
D. MOV 04H, A

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Question 11

The contents of the accumulator after this operation MOV A,#2BH ORL A,00H will be:

A. 1B H
B. 2B H
C. 3B H
D. 4B H

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Question 12

This program code will be executed once: STAT: MOV A, #01H  JNZ STAT

A. TRUE
B. FALSE

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Question 13

The 8051 can handle ________ interrupt sources.

A. 3
B. 4
C. 5
D. 6

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Question 14

The following program will cause the 8051 to be stuck in a loop: LOOP: MOV A, #00H  JNZ LOOP

A. TRUE
B. FALSE

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Question 15

An alternate function of port pin P3.1 in the 8051 is:

A. serial port input
B. serial port output
C. memory write strobe
D. memory read strobe

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Question 16

Which of the following commands will copy the contents of RAM whose address is in register 0 to port 1?

A. MOV @ P1, R0
B. MOV @ R0, P1
C. MOV P1, @ R0
D. MOV P1, R0

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Question 17

The microcontroller is useful in systems that have nonvariable programs for dedicated applications.

A. TRUE
B. FALSE

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Question 18

The following program will receive data from port 1, determine whether bit 2 is high, and then send the number FFH to port 3: READ: MOV A,P1 ANL A,#2H CJNE A,#02H,READ MOV P3,#FFH

A. TRUE
B. FALSE

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Question 19

The 8051 has ________ parallel I/O ports.

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

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Question 20

To interface external EPROM memory for applications, it is necessary to demultiplex the address/data lines of the 8051.

A. TRUE
B. FALSE

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Question 21

The special function registers can be referred to by their hex addresses or by their register names.

A. TRUE
B. FALSE

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Question 22

Microcontrollers often have:

A. CPUs
B. RAM
C. ROM
D. all of the above

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Question 23

Data transfer from I/O to external data memory can only be done with the MOVX command.

A. TRUE
B. FALSE

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Question 24

The designs of a centigrade thermometer and a PWM speed-control circuit can be implemented by the 8051.

A. TRUE
B. FALSE

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Question 25

A HIGH on which pin resets the 8051 microcontroller?

A. RESET
B. RST
C. PSEN
D. RSET

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Question 26

Both registers TL0 and TL1 are needed to start Timer 0.

A. TRUE
B. FALSE

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Question 27

The internal RAM memory of the 8051 is:

A. 32 bytes
B. 64 bytes
C. 128 bytes
D. 256 bytes

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Question 28

Bit-addressable memory locations are:

A. 10H through 1FH
B. 20H through 2FH
C. 30H through 3FH
D. 40H through 4FH

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Question 29

The ADC0804 has ________ resolution.

A. 4-bit
B. 8-bit
C. 16-bit
D. 32-bit

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Question 30

The statement LCALL READ passes control to the line labelled READ.

A. TRUE
B. FALSE

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Question 31

Which of the following instructions will move the contents of register 3 to the accumulator?

A. MOV 3R, A
B. MOV R3, A
C. MOV A, R3
D. MOV A, 3R

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Question 32

This program code will be executed continuously: STAT: MOV A, #01H  JNZ STAT

A. TRUE
B. FALSE

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Question 33

The total external data memory that can be interfaced to the 8051 is:

A. 32K
B. 64K
C. 128K
D. 256K

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Question 34

MOV A, @ R1 will:

A. copy R1 to the accumulator
B. copy the accumulator to R1
C. copy the contents of memory whose address is in R1 to the accumulator
D. copy the accumulator to the contents of memory whose address is in R1

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Question 35

The 8-bit address bus allows access to an address range of:

A. 0000 to FFFFH
B. 000 to FFFH
C. 00 to FFH
D. 0 to FH

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Question 36

Which of the following instructions will move the contents of the accumulator to register 6?

A. MOV 6R, A
B. MOV R6, A
C. MOV A, 6R
D. MOV A, R6

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Question 37

The special function registers are maintained in the next 128 locations after the general-purpose data storage and stack.

A. TRUE
B. FALSE

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Question 38

An alternate function of port pin P3.0 (RXD) in the 8051 is:

A. serial port input
B. serial port output
C. memory write strobe
D. memory read strobe

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Question 39

The address space of the 8051 is divided into four distinct areas: internal data, external data, internal code, and external code.

A. TRUE
B. FALSE

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Question 40

The I/O port that does not have a dual-purpose role is:

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

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Question 41

The last 96 locations in the internal data memory are reserved for general-purpose data storage and stack.

A. TRUE
B. FALSE

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Question 42

When the 8051 is reset and the EA line is LOW, the program counter points to the first program instruction in the:

A. internal code memory
B. external code memory
C. internal data memory
D. external data memory

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Question 43

Which of the following statements will add the accumulator and register 3?

A. ADD @R3, @A
B. ADD @A, R3
C. ADD R3, A
D. ADD A, R3

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Question 44

A label is used to name a single line of code.

A. TRUE
B. FALSE

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Question 45

The following command will copy the accumulator to the location whose address is 23H: MOV 23H,A

A. TRUE
B. FALSE

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Question 46

The total amount of external code memory that can be interfaced to the 8051 is:

A. 32K
B. 64K
C. 128K
D. 256K

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Question 47

This statement will set the address of the bit to 1 (8051 Micro-controller): SETB 01H

A. TRUE
B. FALSE

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Question 48

Which of the following commands will move the number 27H into the accumulator?

A. MOV A, P27
B. MOV A, #27H
C. MOV A, 27H
D. MOV A, @27

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Question 49

The following command will rotate the 8 bits of the accumulator one position to the left: RL A

A. TRUE
B. FALSE

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Question 50

The I/O ports that are used as address and data for external memory are:

A. ports 1 and 2
B. ports 1 and 3
C. ports 0 and 2
D. ports 0 and 3

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Question 51

What is the difference between the 8031 and the 8051?

A. The 8031 has no interrupts.
B. The 8031 is ROM-less.
C. The 8051 is ROM-less.
D. The 8051 has 64 bytes more memory.

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