Re: Joystick Needs for //GS !

[frankc <frankc@srv.net>]

> frankc writes ...
> >
> > Okay, I have looked at what it takes to convert a PC joystick
> > to an Apple II joystick.  I have found it to be suprisingly
> > simple.  I have seen some web sites that discuss using
> > capacitors, resistors, etc...  The problem is some of these
> > tend to lose functionality if you do this.  So I pulled apart
> > a joystick that has both a PC connector and an Apple II (9
> > pin) connector and found that the only thing that is being
> > converted is the digital side, the buttons.  The
> > potentiometer is being fed 5 volts on one side and fed to the
> > Apple and PC input pins.  So I came up with a simple circuit
> > that RETAINS THE RAPID FIRE functionality of some joysticks.
> > I have built a schematic and have made it into a GIF file.  I
> > tried to upload it here, but the message never showed up.
>
>      The net seems to be messing up here and there recently. Your posting
> with the diagram came in okay on my server; thanks for posting it. Your
> diagram is reproduced below. (I added more line colors to help see what's
> going on.)
>

Good

>
> > So if anyone wants it they can have it if they mail me
> > directly.  I have not tested it just yet so be warned it may
> > not be %100 percent.  I will not take resposibility for you
> > torching your computers!  Anyway, it should work fine.
> >
>  ....
>
>      It looks like your design should be fairly torch free. It will not work
> properly as-is because the standard PC joystick's pots max out around 100k
> Ohms, 50k less than the pots on Apple II joysticks.

The commercial version of the joystick I have does not have caps anywhere, but
the pots are
145K on those.  I would bet though that even a 100K would work well on an
Apple.  It may
not have the full range if the Apple assumes a certain time constant or if the
Apple does
calibrate it should work fine.  I will have to defer to people who have used a
joystick in thier
programs and/or are familiar with how the Apple treats a joystick.  I will have
to test this for
myself as well.

>      Adding a small capacitor (approx. 0.01uF) on each paddle lead going to
> Ground should compensate for the difference in max resistances.

To increase the time constant I assume.

>      Using a logic IC to invert Button/RapidFire signals is an interesting
> approach. (The design for doing this referenced on the FAQs KB&Joystick page
> uses PNP transistors.)  Since there is about six feet of wire connected to
> each gate input on the IC, you may need to add pull-up resistors-- about 3.3k
> going to +5V-- on each input to avoid false triggering due to noise.

I am not sure this would not work just fine.  The PC joystick input is TTL as
well.  Parallel ports
are just TTL, and some have pullups and some do not.  The NES uses a CMOS chip
in thier
paddles and the cables are not shielded and seem to be noies immune.  I would
try without and
see how it turns out.

Tell you what, I will build one and test it out and make any adjustments.  I
will build a nine 9 external
and a 16 pin internal adapter to cover the most bases.  I will use the different
joysticks for the tests
as well.  My gut feeling says it will work.  I would hate to add parts when they
are not really needed.

Thanks for the feedback,
Frank