Int 62 Fn 0039 u - Fgdriver V4.02 - "fg_getaddr" - Get Segment Of Active [V]
AX = 0039h
Return: AX = segment of active video page
Note: the FGDRIVER functions are rearranged with each major release, but
their parameters do not change (see #3145 at AX=0000h)
See Also: AX=0042h,AX=00ACh