10  ! This program demonstrates the various pen types by specifying a pen,
20  ! clearing the screen, drawing a box, specifying another pen (but NOT
30  ! clearing the screen!), and drawing a diagonal crisscross the screen -   
40  ! (There are four pen types: -2,-1,0,1.  Try them all.)
50  !
60  PEN 1 @ GCLEAR @ LINE TYPE 1 @ SCALE 0,100,0,50 
70  !
80  PEN -1 @ GCLEAR !           Change pen, clear the screen.
90  MOVE 10,10 @ DRAW 90,10 @ DRAW 90,40 @ DRAW 10,40 @ DRAW 10,10 
100 !               
110 PEN -2 !                    Change the pen again.
120 DRAW 90,40 @ DRAW 10,10 !   Draw a diagonal.
130 !
140 END