PROGRAM PITSTOP
Your Sinclair, September 1990

Despite the fact that he's had a whopping great helmet stuck
to his head for the past three months, JONATHAN DAVIES still
manages to leap into action for yet another instalment of,
you guessed it, Programming Pitstop. Hurrah!

Oh, um, I was just about to have lunch actually. Could you hang on for
a few minutes?

Right, off we go then. It's been a busy month on the whole, what with
one thing and another. Luckily, though, I've been able to take a short
break from my hectic life-"style" to sift through the latest heap of
contributions. And what a corking collection they are. Blimey, yes.
It's been almost impossible to choose the best ones, it really has,
but a decision has had to be made. The results are as follows ...

After an absence of several months from professional Pitstopping, The
Fractal Farm has re-entered the arena with a massive pile of stuff,
the choicest titbits of which are reproduced below. And there are also
a couple of stonking special effects routines from Paul Dias and
William Fraser.

Hokay. You know what comes next - a bit of fancy finger-work on your
part, and hours of unadulterated hex-filled bliss. Go to it.

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FRUITY FRACTAL FRIPPERY
by The Fractal Farm

Plunging straight in at the deep end, here are a couple of dubiously
technical and. extremely complicated progs from our chums down on The
Fractal Farm. And who are they? Well, there's Thomas George Amsler
Rushton (snigger) and Jonathan Scott, who both should really have been
concentrating on their uni exams rather than playing with their
Spectrums. Be grateful they didn't though. Their fractal research has
now progressed into the third dimension, giving us a 3D Mandelbrot
generator which you'll absolutely lurve.

It's Basic all the way, so there's no need to fiddle about with
hexloaders. Just hammer it in and ... eek! It wants you to type in
four numbers! Fear not though. These are the usual Mandelbrot
coordinates, so you could try -2, -2, 4, 50 or indeed -1.5, -.5, .5,
100. Or just about anything, in fact. The results will be impressive,
but they'll take absolutely ages to appear, so be patient.

Next on offer is a Henon Strange Attractor plotter. You'll probably be
wanting to know what a Henon Strange Attractor is, eh? Ah.

Well it says here that it forms an infinitely long line that never
crosses itself using the equations:
	xnew = y + 1 -1.4 x X x X
	ynew = 0.3 x X
which sounds fairly handy to me. You'll also be delighted to hear that
the program features a zoom mode, so pressing 1 while the program is
running will make a little box appear that can be moved around with
the cursor keys (using Shift for added speed), and pressing 0 will
plot the area zoomed in on. Space will start plotting from scratch.

Once again, the speed of the thing falls some way short of "lightning",
so you'll have to either compile it or be extraordinarily patient.

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FADER
by William Frazer

This one speaks for itself really. Er, okay then. It doesn't. What it
is, in fact, is a fader which fades your screen to black any time you
want it to. It comes in hex form, so whip out the hexloader from last
month (or the month before) and type it in. Address 60000 is
recommended as the start one, but you can actually put it anywhere
(it's relocatable, you see). Done that? Right. To get it working,
RANDOMIZE USR 60059. And to alter the speed of the fade? POKE 60066, a
number. And that's it.

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WIZZLE
by Paul Dias

Okay, gimmick fans, this is your lucky day. You might have thought
that new ways of plopping a picture from memory onto the screen were
running pretty thin on the ground these days, but Paul Dias has,
against all probability, come up with another one. And it's got to be
one of the weirdest yet. It sort of "pours" the picture onto the
screen, giving the sort of enthralling effect that you'd be able to
sit and watch for hours if it didn't keep making you need the loo.

To use it you'll need to have a screen lying around on a tape
somewhere, but I'm sure you've got piles of those. As the machine code
is all built into the Basic program, all you've got to do is type it
in and take it from there. Upon running the thing the machine code
will be installed and you'll be given instructions on how to get the
routine working. The trick is to load your picture from tape into
memory somewhere (say, 40000) and then write a couple of lines of
Basic as instructed. These could be incorporated into a larger program
of course. There are various ways of making the screen appear, and
these can be selected by varying the numbers you put into the LET a=FN
... line.
