[Coladam] analog vs. digital joystick input

Geoffrey Oltmans oltmansg at gmail.com
Wed Sep 4 15:47:36 CEST 2013


Nope, that won't work. Still no ADC inputs on the joystick interfaces.

The Atari driving controller (that is used for Indy 500 and a scant few
other games) might be directly adaptable to work, since those controllers
are quadrature-encoded like the Roller Controller is (similar to what is
done for mice), but it would only work for games that use the roller
controller  (and then you'd be missing a fair few buttons). There's no
analog inputs at all on the CV/ADAM. When paddle controllers are used on
the CV or ADAM, it's as Rich describes... the controllers are plugged into
the expansion module, and those are interfaced directly to the TIA chip,
which does have inputs for up to four POTS (the game Warlords would allow
for four paddle players for example). Actually going back and reading the
TIA manual, it appears that these inputs are not "real" ADC inputs, but
rather the potentiometer on the paddle controller is hooked up to a
capacitor. This capacitor is discharged by setting a digital output to dump
the charge and then released. The capacitor is charged and while charging
the system counts how long it takes for the digital input connected to the
capacitor circuit to change to transition from a 0->1 state (or vice
versa). Clever way of doing it really, and probably more akin to how light
pen inputs are done on older computers that had such things (since it
appears to be related to the refresh timing circuitry in the TIA chip).
Probably not near as fast as a real ADC either. At any rate, you could
probably do something like this on the CV, but it would require external
circuitry to support, and either you would have to patch the BIOS or bypass
the joystick scanning routines to do it, but there's enough signals
available through the joystick interface that something similar could be
constructed.



On Wed, Sep 4, 2013 at 6:16 AM, Kevin Powers <kjpmail at gmail.com> wrote:

> What about via a pair of Atari paddles?
>
>
> On Tue, Sep 3, 2013 at 11:42 AM, Geoff Oltmans <oltmansg at gmail.com> wrote:
>
>> Only digital. There are no adc inputs in the joystick ports.
>>
>> Sent from my iPhone
>>
>> On Sep 3, 2013, at 10:35 AM, Kevin Powers <kjpmail at gmail.com> wrote:
>>
>> > Does the Coleco stick send both analog and digital joystick data to the
>> > ADAM?  Or is it only digital?
>> > _______________________________________________
>> > Coladam mailing list
>> > Coladam at adamcon.org
>> > http://adamcon.org/cgi-bin/mailman/listinfo/coladam
>>
>
>


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