INT 10 - VIDEO - SCROLL UP WINDOW
        AH = 06h
        AL = number of lines by which to scroll up (00h = clear entire window)
        BH = attribute used to write blank lines at bottom of window
        CH,CL = row,column of window's upper left corner
        DH,DL = row,column of window's lower right corner
Note:   affects only the currently active page (see AH=05h)
Warning: some implementations have a bug which destroys BP
SeeAlso: AH=72h,AH=73h,AX=7F07h,INT 50/AX=0014h