C $E007 Load HL with the pointer to the currently selected game board object.
C $E00A Reset A. Just for LOL's, I think.
C $E00B Point DE at the start of the game map area.
C $E00E Calculate the offset into the map and stored in HL.
C $E010 Convert upper nibble of L into a value in the range 2-30 and store in H as the vertical coordinate.
C $E017 Load offset back into A, double it, mask off to get a number in the range 2-30 and store it in L as the horizontal coordinate.
C $E01C Increment both coordinates since the highlighted square is 2x2? Or 'cos there is a top border & a left border.
C $E01E Return.