Copies the two bytes from (SP) into the operand, then increases SP by 2.
pop af pop bc pop de pop hl pop ix pop iy
Flags are unaffected except when popping AF.
Used for retrieving values saved on the stack. Also used when you want to load a 16-bit register into another 16-bit register (the LD instruction won't work for this).
rr represents a two byte register pair: BC, DE, HL, SP