Re: Apple /// Joystick

[Rubywand <rubywand@swbell.net>]

Paul Grammens writes ...
> 
> I was trying to get a joystick working on a IIe card. Going thru the
> joysticks I had, I found one in pristine condition. It wouldn't work,
> though. At first I thought that was why it was in such good shape, but then
> I noticed that the pins on the connector were completely different from the
> working joysticks. Looking at the bottom, it says "Cursor ///  A3M0010".
> Could this be for the Apple ///? Does the Apple /// use a different joystick
> pinout?   If so, I could make an adapter so I could use this on either
> model.
> -Paul

     An adapter might be doable; but, it would be a bit more bother than the one used
for PC sticks. Here is some info posted a few years ago by David Empson:

>>

The Apple III joystick port has very little in common with the
Apple II one.  Do not attempt to connect an Apple II joystick to an
Apple III, or vice versa.  At the very least, it will not work.  At
worst, you could damage the computer.

For starters, if you push either button, you will short out the power
supply (+5V will be connected to ground).

Here are the pinouts, for comparison:

   IIe   III

1  SW1   GND
2  +5V   +5V
3  GND   GND
4  PDL2  Joy-X
5  PDL0  SW0
6  SW2   +12V
7  SW0   GND
8  PDL1  Joy-Y
9  PLD3  SW1

Luckily, no single joysticks use pin 7 (SW2).  If you pressed that, you
would short out +12V to +5V, which could do some serious damage to the
motherboard.

The Apple III also uses a different circuit arrangement within the
joystick.

The switch inputs are supposed to have pull-down resistors (270 ohms),
and have a momentary-closed contact to +5V.  (The Apple II doesn't
need a pull-down resistor, but it wouldn't matter if one was there.)

The joystick analog inputs are supposed to be connected so that one
end of each potentiometer is grounded, the other end connected to
+12V, and the wiper goes to the joystick pin.  The potentioment value
can range from 1K ohm to 700K ohm (the manual says that with higher
values, a limited range will be available, so I expect that 100K ohm,
as used in a PC joystick, should be OK).

(The Apple II uses a 150K ohm potentiometer to +5V.  There is no
connection to ground - one end of the pot is left unconnected.)
-- 
David Empson
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Rubywand