Tulunk Village

from data crystal,at the voice pointer

2 Byte Pointers

Game Boy (and Game Boy Color) pointers are typically two bytes long. They are often contained in the same bank as the data that it is supposed to point to, and is usually directly above or below the data. To calculate a pointer from a Game Boy game:

Take the offset that you wish to point to
Take the last four digits of the offset, and cut off the rest
The most significant bit will always be 0, and the second most significant bit will always be 1. In other words:
If the offset is from 0000-3FFF, add 4000 to the offset.
If the offset is from 4000-7FFF, do not add anything to the offset.
If the offset is from 8000-BFFF, subtract 4000 from the offset.
If the offset is from C000-FFFF, subtract 8000 from the offset.
Because Game Boy is little endian, switch the first two digits with the last two. Note: In rare cases, some games, such as Donkey Kong Land 2 or Donkey Kong Land III, will store pointers in big endian, in which case reversing is not necessary.

Example: $1201FA is the offset you wish to point to.

Take the offset $1201FA
Take the last four digits: $01FA
Since $01FA is between 0000-3FFF, you add 4000, so you get $41FA
Because Game Boy is little endian, you take the 41FA, switch the 41 and FA around to get FA41