Screen Modes:

    These are the values that can be used with the ANSI SM (Set Mode)
    Command. The IBM BIOS supports several video modes; the codes
    given in the BIOS documentation are used as parameters to the
    Set Mode command.

     0               text 40x25 Black & White
     1               text 40x25 Color
     2               text 80x25 Black & White
     3               text 80x25 Color
     4               bitmap 320x200 4 bits/pixel
     5               bitmap 320x200 1 bit/pixel
     6               bitmap 640x200 1 bit/pixel
     7               Monochrome mode (cursor wrap kludge)
    13 (EGA)         bitmap 320x200 4 bits/pixel
    14 (EGA)         bitmap 640x200 4 bits/pixel
    16 (EGA)         bitmap 640x350 4 bits/pixel
    17 (VGA)         bitmap 640x480 1 bit/pixel
    18 (VGA)         bitmap 640x480 4 bits/pixel
    19 (VGA)         bitmap 300x200 8 bits/pixel
    43 (EGA/VGA)     set the 43 line (EGA) or 50 line (VGA) mode.
    99               (graphics cursor kludge)

    Codes 13 and on are supported by NNANSI.SYS and some other more recent
    drivers. Mode 99 turns On (set) or Off (reset) the graphic cursor that
    NNANSI provides, Off would be best.