Multiple Choice Questions & Answers on 8051 Microcontroller I/O Port Programming and Addressing Modes

Multiple Choice Questions & Answers on 8051 Microcontroller I/O Port Programming and Addressing Modes

1. Which operator is the most important while assigning any instruction as register indirect instruction?
a) $
b) #
c) @
d) &
Answer: @

2. Which of the following comes under the indexed addressing mode?
a) MOVX A, @DPTR
b) MOVC @A+DPTR,A
c) MOV A,R0
d) MOV @R0,A
Answer: MOVC @A+DPTR,A

3. Which out of the four ports of 8051 needs a pull-up resistor for using it is as an input or an output port?
a) PORT 0
b) PORT 1
c) PORT 2
d) PORT 3
Answer: PORT 0

4. Which of the ports act as the 16 bit address lines for transferring data through it?
a) PORT 0 and PORT 1
b) PORT 1 and PORT 2
c) PORT 0 and PORT 2
d) PORT 1 and PORT 3
Answer: PORT 0 and PORT 2

5. Which instruction is used to check the status of a single bit?
a) MOV A,P0
b) ADD A,#05H
c) JNB PO.0, label
d) CLR P0.05H
Answer: JNB PO.0, label

6. Which of the following registers are not bit addressable?
a) SCON
b) PCON
c) A
d) PSW
Answer: PCON

7. Is this a valid statement?
SETB A
a) yes
b) no
c) cant be determined
d) none of the mentioned
Answer: no

8. To initialize any port as an output port what value is to be given to it?
a) 0xFF
b) 0x00
c) 0x01
d) A port is by default an output port
Answer: A port is by default an output port

9. Which addressing mode is used in pushing or popping any element on or from the stack?
a) immediate
b) direct
c) indirect
d) register
Answer: direct

10. What is the advantage of register indirect addressing mode?
a) it makes use of registers R0 and R1
b) it uses the data dynamically
c) it makes use of operator @
d) it is easy
Answer: it uses the data dynamically

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