Which bits of the 8051 should change after the movx instruction
none, some bits of the 8051 should change during the movx instruction.

The above, of course, exclude things like "the acc will hold the "bits" from the memory location addressed by dptr after movx a,@dptr is executed"

For the above, a wealth of information can be obtained by reading "the bible" chapters 1 and 3 (address in links <---)

Erik