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  Service 00H (decimal 0) is used to configure your video subsystem into one
  of the 20 video modes listed in Figure 9-2. For details of the video
  modes, see page 72.

  You may recall from our discussion in Chapter 4 that modes 00H through
  06H apply to the standard Color Graphics Adapter; mode 07H applies to the
  Monochrome Display Adapter; modes 0DH through 10H were added for the
  Enhanced Graphics Adapter; and modes 11H through 13H were introduced with
  the Multi-Color Graphics Array (PS/2 models 25 and 30) and Video Graphics
  Array (PS/2 models 50, 60, and 80).

  Mode        Type         Resolution  Colors      Video Subsystem
  --------------------------------------------------------------------------
  00H, 01H    Text         40 x 25     16          CGA, EGA, MCGA, VGA
  02H, 03H    Text         80 x 25     16          CGA, EGA, MCGA, VGA
  04H, 05H    Graphics     320 x 200   4           CGA, EGA, MCGA, VGA
  06H         Graphics     640 x 200   2           CGA, EGA, MCGA, VGA
  07H         Text         80 x 25     Mono        MDA, EGA, VGA
  08H, 09H,
  0AH                                              (PCjr only)
  0BH,0CH                                          (used internally by EGA
                                                   BIOS)
  0DH         Graphics     320 x 200   16          EGA,VGA
  0EH         Graphics     640 x 200   16          EGA,VGA
  0FH         Graphics     640 x 350   Mono        EGA,VGA
  10H         Graphics     640 x 350   16          EGA,VGA
  11H         Graphics     640 x 480   2           MCGA,VGA
  12H         Graphics     640 x 480   16          VGA
  13H         Graphics     320 x 200   256         MCGA,VGA
  --------------------------------------------------------------------------

  Figure 9-2.  Video modes available through ROM BIOS video service 00H.

  Normally, the ROM BIOS clears the screen memory buffer when the mode is
  set, even if it is set to the same mode again and again. In fact,
  resetting the same video mode can be an easy way to clear the screen. In
  some versions of DOS, in fact, the DOS command CLS clears the screen this
  way. Setting the video mode also sets the color palette to default color
  values, however, so don't rely on service 00H to clear the screen if
  you're working with colors; use video service 06H instead.

  On the EGA, MCGA, and VGA, you can also tell the ROM BIOS not to clear the
  screen when it sets up the video mode. Do this by adding 80H (decimal 128)
  to the video mode number you specify in AL. For example, to change to 640
  x 200, 2-color mode without clearing the screen, call service 00H with AL
  = 86H. Use this feature with caution, though. Displayable video data is
  formatted differently in different modes, so a screenful of useful data in
  one video mode may become unintelligible when you switch to another mode
  without clearing the screen.

  See Chapter 4, page 72 for more on video modes. See page 58, memory
  location 0040:0049H, for more on how a record of the mode is stored in
  memory. See service 0FH (decimal 15) to find out how to determine the
  current video mode.