Q. DJNZ R0,label is how many bit instruction?

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Q. JZ, JNZ, DJNZ, JC, JNC instructions monitor the bits of which register ?

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Q. Calculate the jump code for again and here if code starts at 0000H

MOV R1,#0
MOV A,#0
MOV R0,#25H
AGAIN:ADD A,#0ECH
JNC HERE
HERE: INC R1
DJNZ R0,AGAIN
MOV R0,A
END

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Q. When the call instruction is executed the top most element of stack comes out to be

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Q. LCALL instruction takes

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Q. Are PUSH and POP instructions are a type of CALL instructions?

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Q. What is the time taken by one machine cycle if crystal frequency is 20MHz?

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Q. Find the number of times the following loop will be executed

MOV R6,#200
BACK:MOV R5,#100
HERE:DJNZ R5, HERE
DJNZ R6,BACK
END

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Q. What is the meaning of the instruction MOV A,05H ?

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Q. Does the two instructions mean the same?
1) BACK: DEC R0

JZ BACK

2) BACK: DJNZ RO, BACK

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Q. To initialise any port as an output port what value is to be given to it?

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Q. Which out of the four ports of 8051 needs a pull-up resistor for using it is as an input or an output port?

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Q. Which of the ports act as the 16 bit address lines for transferring data through it?

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Q. Which of the following registers are not bit addressable?

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Q. Which instruction is used to check the status of a single bit?

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Q. Which addressing mode is used in pushing or popping any element on or from the stack?

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Q. Which operator is the most important while assigning any instruction as register indirect instruction?

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Q. What is the advantage of register indirect addressing mode?

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Q. Which of the following comes under indexed addressing mode?

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Q. Is this a valid statement ?
SETB A

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