[atari7800] Re: Reading both fire buttons ?

  • From: "Andy Mucho" <m00@xxxxxxxxxxxxxxxxxxx>
  • To: <atari7800@xxxxxxxxxxxxx>
  • Date: Wed, 29 Sep 2004 11:19:21 +0100

> > Any press from a dual button pad, also triggers the single button ?
> That's how it is on the real 7800 as well. The Proline controllers
> are wired in such a way that they will trigger the 2600 fire button
> input as well as one of the 2600 paddle inputs.

I suppose that makes sense thinking about it, otherwise how would I have
been able to use the dual-button sticks on the 7800 in 2600 mode? I should
have realised this earlier.. Doh! And I also remember being able to use them
on my C64 back in the 80s which should have hit me earlier :(

> The Falcon source code is from an early prototype. It probably
> was written while the system was still in development. Maybe the
> original Proline joysticks were wired in such a way that the 2600
> fire button wouldn't be triggered in dual button mode. And if it
> was, it might have caused damage to the 7800. Maybe this was changed
> later on. Maybe this is what the resistors are for in Proline
> joysticks and joypads? The 7800 programmers manual doesn't mention
> any potential damage being caused by using dual button support,
> so there probably isn't anything to worry about.

I thought that some of the code in that looked a bit odd.. I was under the
assumption it was a finished title, thought some of the things, ie:
initialisation of the hardware looked a little odd compared to what I'd seen
in Robotron and many others.. I shall forget all the questions I had about
this then, well until me joysticks starting smoking ;p

> But if you still want to be sure, you could check for a change
> on the 2600 fire button input without there being a change on
> one of the paddle inputs at the same time.

Yeah, that sounds like the right thing to do, just check the paddle inputs
and ensure that the 2600 input changes with them if not drop into one button
mode.. Sounds like a good plan. I kind of really like the idea of being able
to auto-magically identify the joystick type and support them both, if
indeed that is even possible.. Either way it's only a couple of lines of

> BTW, if you are still looking for a way to test your game on
> a real 7800 and don't mind doing some soldering, you could have
> a look at the plans for modifying your 7800 and one game cartridge
> into a RAM cart. The PAL 7800 is actually quite easy to modify,
> because some of them already have the BIOS on an EPROM chip.
> You can find the plans on my website at http://home.arcor.de/estolberg/ .
> The nessessary programs are in the tool section and plans for
> better RAM carts and instructions on how to modify the PAL
> console can be found in the link section.

I've seen the BIOS replacement stuff and I'm intrigued, my only problem is
the soldering required for a 128K ROM + 16K RAM cart, and my soldering
skills are about equal to those of a donkey with large gloves on ;)

I'm toying with getting the idea of getting a EPROM Emulator device for
testing, and doing the bare minimum required to convert a 128K cart to
EPROM.. I figure this probably wouldn't be a wasted investment as it'd be
equally applicable and useable on every other system I dabble on..

I'm getting very close to wanting to run on a real machine, as there's a lot
of questions Mess isn't answering for me very clearly, for which actually
seeing the thing on a real screen complete with real artefacts would be
heaven ;)

Anyway, I've got some polygons that need filling ;)



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