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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documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.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
 
  A000:0000   Varies   Video buffer for graphics modes 0Dh and higher.
                       Used by MCGA, EGA, and VGA.
 
  B000:0000   0800h    Video buffer for monochrome text display (mode 7).
              words    Each word of the buffer corresponds to a single
                       character box on the screen, beginning with the
                       upper left corner.
 
                       The high byte of each word contains the character's
                       "display attribute," a value that specifies the
                       character's video appearance, intensity, and blink
                       state. The low byte contains the character's ASCII
                       code.
 
                       For example, a value of 0141h in the fourth word of
                       the buffer produces an underlined "A" (ASCII 41h)
                       at the fourth column of the screen's top row.
 
                       In Hercules monochrome graphics mode, memory from
                       address B000:0000h to B7FF:FFFFh holds graphics
                       data for display page 0.
 
  B800:0000   2000h    Video buffer for color display. Color text words
                       display (modes 0-3) is mapped in attribute/ASCII
                       word pairs as described above for monochrome text,
                       except that each display attribute determines a
                       character's background and foreground colors.
 
                       The buffer provides space for four screen pages in
                       80-column text mode, each page occupying 800h words
                       of memory, or eight screen pages in 40-column text
                       mode. Adapters such as the EGA and VGA provide more
                       buffer area and can accommodate more screen text.
 
                       In CGA graphics modes (modes 4-6), bit data in the
                       buffer corresponds singly or in pairs to individual
                       screen pixels. In Hercules monochrome graphics
                       mode, memory from address B800:0000h to BFFF:FFFFh
                       holds graphics data for display page 1.
 
     See also: Color Attribute Table, Monochrome Attribute Table,
               DOS Segment Map
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