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The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

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  Address
  (hex)       Size      Description
 
  0000:0449   1 byte    Current video mode.
 
  0000:044A   1 word    Number of screen columns (characters per row).
 
  0000:044C   1 word    Size of video buffer in bytes.
 
  0000:044E   1 word    Offset to buffer area used by current display page.
 
  0000:0450   8 words   Cursor coordinates for 8 display pages, beginning
                        with page 0. High byte of each coordinate = cursor
                        row, low byte = cursor column.
 
                        NOTE: top row = 0, leftmost column = 0.
 
  0000:0460   1 word    Current cursor shape. High byte = scan line at
                        top of cursor, low byte = scan line at bottom of
                        cursor, relative to top of character box.
 
                        For example, the normal MDA cursor shape uses
                        lines 11-12 of the 14 scan lines (0-13) that form
                        the character box. In this case, 0000:0460h
                        contains the value 0B0Ch. Changing this value does
                        not change cursor shape.
 
  0000:0462   1 byte    Current display page number.
 
  0000:0463   1 word    Port address of CRT controller index register
                        (03B4h for monochrome, 03D4h for color).
 
  0000:0465   1 byte    Current value in CRT controller mode register
                        at port address 03B8h (monochrome) or 03D8h
                        (color). Used only for MDA and CGA but emulated by
                        other adapters.
 
                        The MDA and CGA mode registers provide write-only
                        access and cannot be read directly. To keep other
                        processes (such as BIOS) informed of the
                        register's contents, programs that reset the
                        register should record the new value at 0000:0465.
 
  0000:0466   1 byte    Current value in CRT controller's color register
                        at port address 03D9h. Used only for CGA but
                        emulated by EGA, MCGA, and VGA adapters.
 
                        The color register, like the mode register
                        described above, cannot be read directly. A program
                        that resets the register should record the new
                        value at 0000:0466.
 
  See also: Interrupt 10h (Video Services)
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