const
  North = 0;
  East  = 90;
  South = 180;
  West  = 270;

procedure Graphics;                                   external 'GRAPH.BIN';
procedure GraphMode;                                  external Graphics[0];
procedure GraphColorMode;                             external Graphics[3];
procedure HiRes;                                      external Graphics[6];
procedure HiResColor(Color: Integer);                 external Graphics[9];
procedure Palette(N: Integer);                        external Graphics[12];
procedure GraphBackground(Color: Integer);            external Graphics[15];
procedure GraphWindow(X1,Y1,X2,Y2: Integer);          external Graphics[18];
procedure Plot(X,Y,Color: Integer);                   external Graphics[21];
procedure Draw(X1,Y1,X2,Y2,Color: Integer);           external Graphics[24];
procedure ColorTable(C1,C2,C3,C4: Integer);           external Graphics[27];
procedure Arc(X,Y,Angle,Radius,Color: Integer);       external Graphics[30];
procedure Circle(X,Y,Radius,Color: Integer);          external Graphics[33];
procedure GetPic(var Buffer; X1,Y1,X2,Y2: Integer);   external Graphics[36];
procedure PutPic(var Buffer; X,Y: Integer);           external Graphics[39];
function  GetDotColor(X,Y: Integer): Integer;         external Graphics[42];
procedure FillScreen(Color: Integer);                 external Graphics[45];
procedure FillShape(X,Y,FillCol,BorderCol: Integer);  external Graphics[48];
procedure FillPattern(X1,Y1,X2,Y2,Color: Integer);    external Graphics[51];
procedure Pattern(var P);                             external Graphics[54];
procedure Back(Dist: Integer);                        external Graphics[57];
procedure ClearScreen;                                external Graphics[60];
procedure Forwd(Dist: Integer);                       external Graphics[63];
function  Heading: Integer;                           external Graphics[66];
procedure HideTurtle;                                 external Graphics[69];
procedure Home;                                       external Graphics[72];
procedure NoWrap;                                     external Graphics[75];
procedure PenDown;                                    external Graphics[78];
procedure PenUp;                                      external Graphics[81];
procedure SetHeading(Angle: Integer);                 external Graphics[84];
procedure SetPenColor(Color: Integer);                external Graphics[87];
procedure SetPosition(X,Y: Integer);                  external Graphics[90];
procedure ShowTurtle;                                 external Graphics[93];
procedure TurnLeft(Angle: Integer);                   external Graphics[96];
procedure TurnRight(Angle: Integer);                  external Graphics[99];
procedure TurtleDelay(Delay: integer);                external Graphics[102];
procedure TurtleWindow(X,Y,W,H: Integer);             external Graphics[105];
function  TurtleThere: Boolean;                       external Graphics[108];
procedure Wrap;                                       external Graphics[111];
function  Xcor: Integer;                              external Graphics[114];
function  Ycor: Integer;                              external Graphics[117];