PROGRAM BOX; {a program that draws some boxes with the LINE procedure}

VAR
   I1:INTEGER;
   PC:INTEGER;
   
PROCEDURE NEXTCOLOR; {color 0 = invisible; 1..3 depend on palette setting}
BEGIN
   IF PC = 3 THEN PC := 1 ELSE PC := PC + 1;
END;

PROCEDURE BOX(SIDE:INTEGER);
BEGIN
   DRAW(10,10,10+SIDE,10,PC);
   DRAW(10+SIDE,10,10+SIDE,10+SIDE,PC);
   DRAW(10+SIDE,10+SIDE,10,10+SIDE,PC);
   DRAW(10,10+SIDE,10,10,PC);
END;

BEGIN
   SETMODE(19);          {selects 320x200 color graphics}
   CURSOR(0,20);
   WRITELN('box demo program');
   FOR I1 := 1 TO 10 DO 
      BEGIN
         BOX(I1*10);
         NEXTCOLOR;
      END;
   READLN;              {requires a CR before resetting the mode}
   SETMODE(3);          {select 80 column text mode}
END.