
PROGRAM PITSTOP
Your Sinclair, July 1993

Back (back! Back!) after a month of, er, not
being here, it's CRAIG "Not here" BROADBENT!

For those amongst you suffering from Pitstop withdrawal symptoms, fear
not, for I have returned! For the less astute, it seems that Pitstop
didn't appear in YS last month due to a problem at my end which I have
failed completely to identify. So commiserations to Paul Seamark,
whose luvverly SAM menu system would otherwise have been gracing the
Pitstop pages, but, as they say, c'est la vie. More to the point, it
means that I won't get paid for all my hard work last month, so I'll
try to slip some of it in here cunningly, thus reducing my gargantuan
workload (some of us have got exams to revise for as well, you know).


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THE BEAST
by M.P. Carter

After thirteen issues' absence, MP (who still offers no elaboration on
those elusive initials) finds himself back in the focus of the
Spectrum programming world, with a routine which he himself described
as "a complicated beast". (Hence the name, you see. It would probably
be more apt to describe it as "a routine offering two collision
detection functions which are much faster than the BASIC alternatives,
along with a demo program to show the routines in action", but we
might have had a spot of trouble fitting that in as the title.)

Anyway, fine routine that it is, let's have a look at how to use it.
To get it up and running, just type in the BASIC, which will not only
enter the code for you, but will also provide you with a demo (as
mentioned) in which you have to move a blob around while avoiding
being eaten by the terrifying copyright symbol. The routine acts on
variables x and y (the screen co-ords of your blob), so these must be
defined before you start. The first function is at 64245 and LET A=USR
64245 will read the keyboard for any one of eight directions (using
the keys Q to T for up, A to G for down, O or L for left and P or
ENTER for right), and places in A the ATTR value for the intended
position of your blob. The second function, called by LET A=USR 64248,
places in A the ATTR value for the actual position of your blob. With
reference to the demo, the first function is used to determine whether
your blob is about to run into a * or a $ sign, and the second is used
to tell you when you've been 'got' by the rabid copyright symbol.

To round off, just a few little bits of info for those to whom the
word 'generic' means 'not for long'. The values for x and y are stored
at 64154 and 64155 respectively, and you can adjust the screen area
used by POKEing 64173, (left edge-1), 64183, (right edge+1), 64202,
(top-1) and 64220, (bottom+1). The maximum value for the bottom is 22,
and you can wrap the values round, so that POKE 64173,255 gives a left
edge of 0.


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SPIROGRAPH
by Stephen Pert

It's been said that people in glass houses shouldn't throw stones, so
I'll refrain from commenting on Stephen's surname, concentrating
rather on this little program he's sent in which, er, makes pretty
patterns. It's all done in one swift burst by using a triple-
parametered DRAW command, and you can change the values in lines 100
and 110 to make new shapes (keep the values odd, though). When you see
one you like, hold down BREAK and the program will eventually stop,
allowing you to save it off as a SCREEN$, or whatever it is you want
to do with it.


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BORDER PRINT
by Andrew Burfield

[The listing for this was only one line long (line 100), but they printed]
[it merged into a duplicate of the Spirograph listing.               JimG]

Cheap visual effects time and thanks go out to Owen Stott, who sent in
something similar. Completely dependent on the speed at which the
program is executed try replacing FOR f=1 TO 5, also leaving out the
FOR ... NEXT loop altogether, and also leaving out both the FOR ...
NEXT and the IF ... THEN, replacing them with PAUSE 1. This last
option is a bit useless application- wise, but it does give a static
effect. Be warned, 128K users will get different results to those
here, so experiment until you get something nice.


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OWEN'S BIT

You'll remember that last time I asked you for program suggestions -
what you wanted to see in Pitstop and all that sort of thing. Well,
Owen Southwood of Woodbridge in Suffolk (blimey, I sound like a crap
radio presenter, don't I, readers?) has given his opinion on all
things Pitstoppy ...

"The initial spark which fires the imagination of a
games-programmer-to-be is the typing in of their first BASIC game.
Okay, so it might be crap. Okay, so it's written in BASIC and
commercially unusable. But it works! From there it's a short step to
writing bigger, better and faster games, and from there to (gasp!)
machine code. I believe that if we were given the opportunity to show
others what we have done - a reason to write games in BASIC, machine
code or a mixture of both - then a whole new generation of games
programmers will develop. This is how it all started for the Speccy,
with the mags printing readers' games. There was a great enthusiasm to
push the Speccy further and further.

"My suggestion is to print readers' games in Pitstop - like the
Program Power pull-out section of old. Why not promise a place on the
cover-tape for any that are good enough?"

Some interesting points there, Owen. What do you other folks think?
Write on in! Maybe Jonathan will give me 10 extra pages to fill with
all the material you peeps have been coming up with! Or something.
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