380 DRAW cx%+px%(st,x%),cy%+py%(st,x%),
l+(st MOD 3)
390 DRAW cx%+px%(st,x%+l),cy%+py%(st,
x%+l),l+(st MOD 3)
400 NEXT x%
410 IF st=5 THEN RETURN
420 lc(st)=0
430 cx(st+l)=cx(st)+l.5*r(st)*SIN(sa+lc(st))
440 cy(st+l)=cy(st)+l.5*r(st)*COS(sa+lc(st))
450 st=st+l st=st+l
460 GOSUB 340
470 st=st-1
480 lc(st)=lc(st)+2*sa
490 IF (lc(st) MOD 360)<>0 THEN 430
500 RETURN
510 ik(l)=l+RND*25
520 IF ik(l)=ik(2) OR ik(l>=ik(3) THEN 510
530 INK 1,ik(1)
540 RETURN
550 ik(2)=1+RND*25 ik(2)=1+RND*25
560 IF ik(2)=ik(l) OR ik(2)=ik(3) THEN 550
570 INK 2,ik(2)
580 RETURN
590 ik(3)=1+RND*25 ik(3)=1+RND*25
600 IF ik(3)=ik(l) OR ik(3)=ik(2) THEN 590
610 INK 3,ik(3)
620 RETURN
When you RUN this program, it will ask you a question (line 40) - answer 3 for the speediest
results. The program will then display the message Calculating, and display a dot . every few
seconds (line 245) to indicate that it is still ‘thinking’ to itself and confirm that the program is still
running.
The subroutines called by lines 300-320 flash the different coloured inks at the rates determined by
the E V E R Y command. If you want to slow down the flashing, E D I T lines 300-320 to read:
300 EVERY 250,l GOSUB 510
310 EVERY 150,2 GOSUB 550
320 EVERY 50,3 GOSUB 590
To see what you have done, look up the E V E R Y command in Chapter 8, it’s one of the most useful
features in AMSTRAD BASIC. One interesting effect of the E V E R Y command is the way it stacks
up requests to do something if the program is interrupted by pressing the [ESC] key - only ONCE.
Pause the operation of the program for a few seconds by doing this, then restart by pressing ‘any
key’. The display will flash frantically as the ‘queued’ timing instructions rush through to catch up.
There’s only a finite amount of space in the queue, so after a while, the new EVERY command gets
discarded until space is made by allowing those in the queue to work their way through.
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