Changes

An 8-bit zero-page address and the X register are added, without carry (if the addition overflows, the address wraps around within page 0). The resulting address is used as a pointer to the data being accessed. Note that, effectively, this makes the X register an index into a list of pointers. Also note that pointers are two bytes long, so the X register should be an even number when accessing a list of pointers (otherwise you'll get half of one pointer and half of another).