Way to detect 4 player joystick adapter?

[earok]

I was wondering if there was a way to detect if a 4 player joystick adapter (Dynablaster style) is present.

Also if there's a general guide on how to use it. The closest I've found is the source code for a Blitz Basic third party library

[koobo]

The joysticks are wired to parallel port pins which are directly available in the CIA registers:

bit 2 in $bfd000 = adapter port 1 fire
bit 0 in $bfd000 = adapter port 2 fire
bits 0-3 in $bfe101 = adapter port 1 directions
bits 4-7 in $bfe101 = adapter port 2 directions

These are active low signals. I read some example sources in the recent past where these were used, I added support to my own application successfully.

[phx]

Correct. I bought a 4-player adapter in the 90s and started to write some games using it, so I could check my old sources.

The directions are:

• bit 7/3 : right
• bit 6/2 : left
• bit 5/1 : down
• bit 4/0 : up

And don't forget to clear all bits in DDRB to make all lines of port B input.

[Korodny]

Originally Posted by phx

started to write some games using it

Anything that got released? Just wondering if I missed some four player classics

[earok]

Thanks all, that's a very handy reference!

[phx]

Originally Posted by Korodny

Anything that got released?

No. Most games we did in the 90s have never been finished. The source I checked for the 4-player adapter was M.U.L.E. 92 (only intro and player-selection exists): https://night.owl.de/index.php?id=56

[Daedalus]

Yup, reading is pretty simple as described. I have also seen (and built) adaptors that support two buttons on the extra controllers, but that's not a standard feature.

As for detection, there's no way to detect it because it's completely passive. All the joystick inputs are open-circuit until they're actually used, so electrically there's no difference between an empty parallel port and a 4-player adaptor with untouched joysticks. It would be trivial to add a little bit of logic to enable detection, but with so many passive adaptors out there, the horse has bolted on that one.

[earok]

Originally Posted by Daedalus

Yup, reading is pretty simple as described. I have also seen (and built) adaptors that support two buttons on the extra controllers, but that's not a standard feature.

Do you mind if I ask how you would read the second button on such an adapter? I'm assuming it's just different bits on $bfd000 to the single button? Also does WinUAE emulate such an adapter?

The reason I'm interested in supporting second fire is future proofing for Scorpion - there are at least some four player games in development (notably Mixel's Wizonk). It would be cool to offer, for example, second fire jump on custom parallel port adapters that have that feature.

[Daedalus]

Yeah, just reading a couple of the extra control bits in $bfd000 - the exact bit I'm not sure of. I'll have to dig out my adaptor to see which lines I used, but as far as I know, there's not a single game that uses it, and WinUAE doesn't emulate it. Probably the only software that does use it is ControllerTest, a controller tester I wrote.

I would suggest that adding it to Scorpion would be a good way of establishing a standard for 2-button 4-player adaptors, so any way you can get it working would be a valid approach.

Edit: Gah, now I'm just thinking about a way to go the whole hog and do an active 4-player adaptor with support for CD32-type controllers via the parallel port, with backwards compatibility for games expecting the standard 1-button 4-player adaptor. I don't need any more projects...

[Toni Wilen]

WinUAE has "Parallel port Joy1 Spare/2nd Button" input event that maps to normally unused parallel port pin (not mapped by default). I think there was at least one game that used it.