This routine forces the scale factor to 0x7F, and then moves the pen to the location pointed to by the X register. The relative y and relative x coordinates are both 2 byte quantities; however, only the most signicant byte of each is of any interest. The values pointed to by the X register have the following format:
X => (rel y hi),(rel y lo), (rel x hi), (rel x lo)
The position moved to is obtained by y=(0,x) & x=(2,x).
DP = $D0
X-reg points to double-sized coordinate pair