fcol: byte = 7;
  bcol: byte = 0;
  bt_double    = 15;     bt_single    =   0;
  black        = 00;     blue         = 01;
  green        = 02;     cyan         = 03;
  red          = 04;     magenta      = 05;
  brown        = 06;     lightgray    = 07;
  darkgray     = 08;     lightblue    = 09;
  lightgreen   = 10;     lightcyan    = 11;
  lightred     = 12;     lightmagenta = 13;
  yellow       = 14;     white        = 15;
  blink        = 128;

  _unknown     = $7f;
  _absent      = 0;                 { no adapter installed           }
  _mono        = 1;                 { monochrome type adapter        }
  _color       = 2;                 { color type adapter             }

  _biosseg     = $0040;             { segment of bios/dos communica- }