Re: Reading Joystick Position

["Mark Cummings" <NOTfigjams@primus.com.au>]

> ...and the reason why the timing is crucial is because you *must*
> wait while the capacitors in the joystick discharges, or you will
> end up reading bogus values. Hence, the NOPs (no-operations) inserted
> simply to waste a little time in precisely known amounts of delay.

Normally there are no capacitors in the joystick for an Apple ][ (not
counting line capacitance of course which is negligable)
the RC timing components are 1. capacitor on the motherboard and 2. resistor
in the paddle/joystick.

there is a mod/circuit in Rubywand's FAQ that describes how to modify a PC
joystick that normally uses a 100K potentiometer to make it compatable with
the Apple ][ which expects a 150K potentiometer (for full control). I have
yet to build it, but basically the circuit adds capacitance to the joystick
port to alter the C value in the RC time constant. this has the effect of
allowing a PC's 100K pot to work correctly on an Apple ][.

Mark