colorback (1)
drawbox (0, 0, maxx, maxy, 2)
color (11)
locate (2, 20)
put "G R E E K   M O D E L   O F   T H E   A T O M"

% draw the atom
drawoval (100, 230, 55, 42, 4)
drawfill (100, 230, 4, 4)
% draw pointer line
drawline (120, 240, 180, 280, 15)
drawline (180, 280, 250, 280, 15)

% write description of model
color (12)
locatexy (260, 280)
put "An atom is a hard, spherical,"
locatexy (260, 270)
put "indivisible particle."

% quit button
drawbox (85, 61, 115, 83, 5)
drawbox (88, 64, 112, 80, 13)
drawfill (90, 65, 13, 13)
colour (14)
locate (22, 7)
put "PRESS ANY KEY"
locate (23, 7)
put "FOR MAIN MENU"
% pattern box draw
delay (500)

drawpage
% textual information on Greek model of the atom
locate (9, 47)
color (2)
put "GREEK BELIEFS"
color (3)
locate (11, 27)
put "  In the fourth and fifth centuries B.C., a school"
locate (12, 27)
put "of  Greek  philosophers  believed  that  matter is"
locate (13, 27)
put "composed of  atoms  (from Greek,        ,  meaning"
color (12)
locate (13, 60)
put "ATOMOS"
color (3)
locate (14, 27)
put "uncut) that are tiny and indestructable.  However,"
locate (15, 27)
put "this was never  verified by experiments  so it was"
locate (16, 27)
put "discarded. It was then reintroduced by John Dalton"
locate (17, 27)
put "over  two  thousand  years later in  1803.  Dalton"
locate (18, 27)
put "developed this model to such an extent that it was"
locate (19, 27)
put "able to explain laws of chemical change."
delay (600)

flush

% atom having the illusion of revolving
x := 55
loop
    exit when hasch
    if x = 1 then
	x := 1
	loop
	    exit when hasch
	    x := x + 6
	    drawarc (100, 230, x, 42, 270, 90, 12)
	    drawarc (100, 230, x, 42, 270, 90, 4)
	    % draw pointer line
	    drawline (120, 240, 180, 280, 15)
	    if x = 55 then
		drawoval (100, 230, 55, 42, 12)
		drawoval (100, 230, 55, 42, 12)
		drawoval (100, 230, 55, 42, 12)
		drawoval (100, 230, 55, 42, 12)
		drawoval (100, 230, 55, 42, 4)
	    end if
	    exit when x = 55
	    exit when hasch
	end loop
	exit when hasch
    else
	exit when hasch
	% draw pointer line
	drawline (120, 240, 180, 280, 15)
	x := x - 6
	drawarc (100, 230, x, 42, 90, 270, 12)
	exit when hasch
	drawarc (100, 230, x, 42, 90, 270, 4)
    end if
    exit when hasch
end loop

   %  following pixel graphic procedures give the illusion of the
   %  exit button being pressed.
drawfill (90, 65, 0, 0)
drawbox (92, 69, 107, 75, 5)
drawfill (94, 70, 5, 5)
sound (500,100)
delay (200)
drawfill (94, 70, 0, 0)
drawbox (88, 64, 112, 80, 13)
drawfill (90, 65, 13, 13)
delay (100)
