{***************************************}
{                OVLTEST                }
{				        }
{           by Jeff Duntemann           }
{                                       }
{ Overlay demo program for Turbo Pascal }
{***************************************}    	

PROGRAM OVLTEST;

VAR QUIT   : BOOLEAN;
    NUMBER : INTEGER;


OVERLAY PROCEDURE ONE;

BEGIN
  WRITELN('>>Hi!  Overlay procedure #1 at your service!')
END;


OVERLAY PROCEDURE TWO;

BEGIN
  WRITELN('>>Number two here.  May I help you?')
END;


FUNCTION GETNUMBER : INTEGER;

VAR I  : INTEGER;
    OK : BOOLEAN;

BEGIN
  REPEAT
    GOTOXY(43,18);
    CLREOL;
    READ(I);
    IF (I >= 0) AND (I <= 4) THEN OK := TRUE ELSE
      BEGIN
        GOTOXY(1,24);
        WRITELN('Valid numbers are 0-4 only!');
        OK := FALSE;
      END
  UNTIL OK;
  GETNUMBER := I
END;


OVERLAY PROCEDURE THREE;

BEGIN
  WRITELN('>>Numbah three.  Whaddaya want?')
END;


OVERLAY PROCEDURE FOUR;

BEGIN
  WRITELN('>>Four''s on line--lay some work on me!')
END;


BEGIN  { MAIN }
  CLRSCR;
  REPEAT
    GOTOXY(1,18);
    WRITE('>>>Enter a number from 1-4 or 0 to quit: ');
    NUMBER := GETNUMBER;
    IF NUMBER = 0 THEN QUIT := TRUE ELSE
      BEGIN
        QUIT := FALSE;
        GOTOXY(1,5); CLREOL;
        CASE NUMBER OF
          1 : ONE;
          2 : TWO;
          3 : THREE;
          4 : FOUR
        END
      END
  UNTIL QUIT;
END.