OK, this is nice and easy. What we're going to do is to scroll the screen in a big circle so that the physical screen just touches each edge of the logical screen.
The formula for moving in a circle, as if you need telling, is:
X = sin(angle) * xradius + xcenter Y = cos(angle) * yradius + ycenter
I am assuming that we were able to set the Logical screen width to twice that of the X
resolution, and that the variable MaxScans has been set from page 5.
So, first calculate the size of the circle to move in:
xcenter = (Xresoluion - LogicalWidth) / 2 xradius = (Xresoluion - LogicalWidth) / 2 ycenter = (Yresoluion - MaxScans) / 2 yradius = (Yresoluion - MaxScans) / 2Now, make the screen scroll in a full circle in steps of 0.1 of a degree.
for angle=0 to 720 in steps of 0.1 begin loop AX = 4F07h BX = 0 CX = sin(angle) * xradius + xcenter DX = cos(angle) * yradius + ycenter call int 10h end loop