I use it for the game under work, because it draw the objects vertically, screen size is 92x112 pixels (256 col mode), very good, because of fast vertical movement during drawing, 1st video screen starts at xx00h, the 2nd starts at xx60h, xxc0h-xxffh are used for other data in the 1st video page, so the bigger waste is on the 2nd video screen from xx5dh-xx5fh and xxbdh-xxffh. The best would be to arrange the sprites also with this solution, so add hl,de could be avoided, I will try to do it also to get small additional speed, and I using port 82h to change between the 2 screens.