Important Notice

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documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

   ◄Summary►  ◄Notes►  ◄Back►
──────────────────────────────────────────────────────────────────────────────
 
    On the EGA and MCGA, the bits of BL are used as follows:
 
    Bits   Significance
    ════   ═════════════════════════════════════════════════════════
    0-1    character block selected by attribute bytes with bit 3=0
    2-3    character block selected by attribute bytes with bit 3=1
    4-7    not used (should be 0)
 
    On the VGA, the bits of BL are used as follows:
 
    Bits   Significance
    ════   ═════════════════════════════════════════════════════════
    0,1,4  character block selected by attribute bytes with bit 3=0
    2,3,5  character block selected by attribute bytes with bit 3=1
    6-7    not used (should be 0)
 
    When using a 256-character set, both fields of BL should select the same
    character block. In such cases, character attribute bit 3 controls the
    foreground intensity.
 
    When using 512-character sets, the fields of BL designate the blocks
    holding each half of the character set, and bit 3 of the character
    attribute selects the upper or lower half of the character set.
 
    When using a 512-character set, a call to Int 10H Function 10H
    Subfunction 00H with BX =0712H is recommended to set the color planes
    to eight consistent colors.
                                    -♦-