Dot_ix ($F2C1)
This routine draws a dot at the relative y and relative x position pointed to by the X register. Afterwards, the X register is incremented by 2.
ENTRY:
DP = $D0
X-reg points to the (y,x) coordinate pair
$C828 contains the intensity (Dot_ix only)
EXIT:
X-reg incremented by 2
D-reg trashed