Int 10 Fn 12  - Video - Alternate Function Select (vga, Mcga) - Video Add  [V]

   AH = 12h
   BL = 32h
   AL = new state
       00h enable video addressing
       01h disable video addressing

Return: AL = 12h if function supported
Desc:  specify whether the CPU should have access to video memory and the
     display adapters I/O registers