Types, Variables, Constants

Color definitions :

  Black = 0;
  Blue = 1;
  Green = 2;
  Cyan = 3;
  Red = 4;
  Magenta = 5;
  Brown = 6;
  LightGray = 7;
  DarkGray = 8;
  LightBlue = 9;
  LightGreen = 10;
  LightCyan = 11;
  LightRed = 12;
  LightMagenta = 13;
  Yellow = 14;
  White = 15;
  Blink = 128;

Miscellaneous constants

  TextAttr: Byte = $07;
  TextChar: Char = ' ';
  CheckBreak: Boolean = True;
  CheckEOF: Boolean = False;
  CheckSnow: Boolean = False;
  DirectVideo: Boolean = False;
  LastMode: Word = 3;
  WindMin: Word = $0;
  WindMax: Word = $184f;
  ScreenWidth = 80;
  ScreenHeight = 25;

Some variables for compatibility with Turbo Pascal. However, they're not used by Free Pascal.

var
  checkbreak : boolean;
  checkeof : boolean;
  checksnow : boolean;

The following constants define screen modes on a DOS system:

Const
  bw40 = 0;
  co40 = 1;
  bw80 = 2;
  co80 = 3;
  mono = 7;

The TextAttr variable controls the attributes with which characters are written to screen.

var TextAttr : byte;

The DirectVideo variable controls the writing to the screen. If it is True, the the cursor is set via direct port access. If False, then the BIOS is used. This is defined under DOS only.

var DirectVideo : Boolean;

The Lastmode variable tells you which mode was last selected for the screen. It is defined on DOS only.

var lastmode : Word;