AMSTRAD CPC464 User Manual page 112

Here' s an example of a program that uses all the items mentioned so far, and introduces a couple
more useful concepts. See how the first line (10) sets up the colour and ink conditions to make sure
that whatever was in the memory of the CPC464 at the time is reset to produce the expected results:
1 0 I N K 0 , 0 :I N K 1 , 2 6 : I N K 2 , 6 : I N K 3 , 1 8 : B O R D E R 0
2 0 R E M t h i s p r o g r a m s d r a w s p a t t e r n s
3 0 m o d e l : D E G
4 0 P R I N T " 3 ,4 o r 6 s i d e d p a t t e rn ? ";
5 0 L I N E I N P U T p $
6 0 I F p $ = " 3 " T H E N s a = 1 2 0 : G O T O 100
7 0 I F p $ = " 4 " T H E N s a = 1 3 5 : G O T O 100
8 0 I F p $ = " 6 " T H E N s a = 1 5 0 : G O T O 1 0 0
9 0 G O T 0 5 0
1 0 0 P R I N T : P R I N T " C a l c u l a t i n g " ;
1 0 5 I F p $ = " 3 " T H E N O R I G I N 0 ,-5 0 , 0 , 6 4 0 , 0 , 4 0 0
E L S E O R I G I N 0 , 0 , 0 , 6 4 0 , 0 , 4 0 0
1 1 0 D I M c x ( 5 ) , cy(5),r( 5 ) , l c ( 5 )
1 2 0 D I M n p ( 5 )
1 3 0 D I M p x % ( 5 , 8 1 ) , p y % ( 5 , 8 1 )
1 4 0 s t = l
1 5 0 c x ( l )= 3 2 0 : c y ( l ) = 2 0 0 : r ( l ) = 8 0
1 6 0 F O R s t = l T O 4
1 7 0 r ( s t + l ) = r ( s t ) / 2
1 8 0 N E X T s t
1 9 0 F O R s t = l T O 5
2 0 0 l c ( s t ) = 0 : n p ( s t ) = 0
2 1 0 n p ( s t ) = n p ( s t ) + l
2 2 0 p x % ( s t , n p ( s t ) ) = r ( s t ) * S I N ( l c ( s t ) )
230 p y % ( s t , n p ( s t ) ) = r ( s t ) * C O S ( L c ( s t ) )
2 4 0 l c ( s t ) = l c ( s t ) + 3 6 0 / r ( s t )
2 4 5 I F ( l c ( s t ) M O D 6 0 ) = 0 T H E N P R I N T " . " ;
2 5 0 I F l c ( s t ) < 3 6 0 T H E N 2 1 0
252 p x % ( s t , n p ( s t ) + l ) = p x % ( st,l)
2 5 4 py%( s t , n p ( s t > + l ) = p y % ( s t , l )
2 6 0 N E X T s t
2 6 5 C L S : i n k 1,2
2 7 0 s t = l
2 8 0 G O S U B 340
29 0 L O C A T E 1,1
3 0 0 E V E R Y 2 5 , l G O S U B 510
3 1 0 E V E R Y 1 5 , 2 G O S U B 550
3 2 0 E V E R Y 5 , 3 G O S U B 590
5 3 0 G O T 0 3 3 0
3 4 0 R E M d r a w c i r c l e p l u s 3 , 4 or 6 o t h e r s
a r o u n d i t
3 5 0 c x % = c x ( s t ) : c y % = c y ( s t ) : l c ( s t )=0
3 6 0 F O R x % = 1 T O np(st)
3 7 0 M O V E c x % , c y %
/more