The 8051 Microcontroller Questions and Answers

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Showing 10 of 59 questions
Q21
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
Answer: Option C
Q22
The contents of the accumulator after this operation MOV A,#0BH ANL A,#2CH will be
  • A 11010111
  • B 11011010
  • C 00001000
  • D 00101000
Answer: Option C
Q23
This program code will be executed once: STAT:     MOV A, #01H      JNZ STAT
  • A TRUE
  • B FALSE
Answer: Option B
Q24
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
Answer: Option C
Q25
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
Answer: Option D
Q26
Data transfer from I/O to external data memory can only be done with the MOV command.
  • A TRUE
  • B FALSE
Answer: Option B
Q27
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
Answer: Option B
Q28
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
Answer: Option A
Q29
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
Answer: Option D
Q30
The number of data registers is:
  • A 8
  • B 16
  • C 32
  • D 64
Answer: Option C

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