Q. When 8051 wakes up then 0x00 is loaded to which register?

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Q. When the micro controller executes some arithmetic operations, then the flag bits of which register are affected?

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Q. How is the status of the carry, auxiliary carry and parity flag affected if write instruction
MOV A,#9C
ADD A,#64H

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Q. How are the bits of the register PSW affected if we select Bank2 of 8051?

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Q. If we push data onto the stack then the stack pointer

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Q. On power up, the 8051 uses which RAM locations for register R0- R7

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Q. How many bytes of bit addressable memory is present in 8051 based micro controllers?

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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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