题目内容

()=F0H, (R1)=40H, and (40H)=0FH. After execution of an instruction “XCHD A, @R1”, the contents of A will be( )

A. 00H
B. F0H
C. 0FH
D. FFH

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()=FEH, ()=1. After execution of instruction “RR A”, the contents of A will be ( )

A. FCH
B. 7FH
C. F1H
D. FDH

Addition instruction of the 8051 can affect ( )

A. CY flag
B. CY and AC flags
CY, AC, and OV flags
D. CY, AC, OV, and P flags

Which of the following instruction will move the value of port 3 to the register R2? ( )

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

Which of the following instruction will copy the contents of RAM whose address is in register R0 to port 3? ( )

A. MOV @P3, R0
B. MOV @R0, P3
C. MOV P3, @R0
D. MOV P3, R0