Ghost button presses on IPAC4 -- bad MAME key assignments?

[Roo5676]

The question: Is there a definitive list of known "problem" keys to avoid using when setting up a keyboard encoder for use in MAME?

The details:

I have a Quad Controller from mameroom.com with an IPAC4 in it.  After getting it configured to my liking for all the different programs I run, everything seemed to work great.  Played some intense 2 player games and tested out the buttons of all 4 players individually.

I wasn't having any problems until I had my first 4-player arcade night.  Most games (X-Men, Bomberman, Power Stone 2 on DreamCast), never showed any problems that I know of, despite chaotic tapping of buttons from all four players (although it might be a bit hard to notice if there was).  But when we were playing NBA Jam, there were occasional random phantom/ghost key presses.  I would be running down the court (holding turbo) and then my guy would just jump into the air or shoot unexpectedly -- usually when someone else jumped/shot.  It's worth noting that jump and shoot are the same button.  It happened to me for awhile, then other people on and off throughout the session.  Sometimes it was fine for a bit and didn't happen to anyone.  I don't think it ever happened to player 4, just players 1-3 at different points.

I am not using any special/windows keys in my set up.  It's pretty much all letters, numbers, special characters like ";" "?", etc., and number pad numbers.  I am not using CTRL, ALT, WIN, HOME, END, PG UP, PG DN, INS, DEL, PRT SCR, PAUSE, F1-F12 etc.

Now I've read that the IPAC is not supposed to have any ghosting or maximum simultaneous key press issues.  I also had changed the buttons on NBA Jam to buttons 7, 5 and 6 to be more comfortable for that game (default MAME buttons for other games like X-Men are 1, 2, 3; PowerStone on NullDC is set for 1, 2, 4, 5).

So the big question is...Are there keyboard keys which are known to cause issues in MAME, outside of the ones mentioned above?  I've searched and searched but couldn't find a definitive list -- just topics about people accidentally hitting ALT-ENTER, etc.

Here are the keys we were using to play NBA Jam when I was seeing the phantom button presses.  Does anything jump out?  I'm a little suspicious of "[" on P4, since P4 never experienced the issue to my knowledge.  I suspect MAME because I saw no problems on Power Stone 2 on NullDC, using a lot of the same buttons.

Player 1
Joystick: (Up) (Down) (Left) (Right)
Buttons: (C) (Number Pad 5) (Z)

Player 2
Joystick: (R) (F) (D) (G)
Buttons: (/) (W) (,)

Player 3
Joystick: (I) (K) (J) (L)
Buttons: (Number Pad 6) (O) ( ; )

Player 4
Joystick: (Y) (N) (V) (U)
Buttons: (\) (M) ([)

Thanks...

[vagabound]

What MAME build and what version are you using?

What is your setting for waitvsync & syncrefresh?


I normally get ghost input even in single player games, no matter what mapping, with many version of official MAME build when I try to sync the game with monitor for smooth scrolling. The only MAME build and version on Windows I found so far that gets me smooth scrolling with good sound synchronisation and without ghost input is WolfMAME.106, which is official and only MAME build allowed for setting world records at Twin Galaxies, so it makes sense to use this build if only for the reference since it has been tested quite a bit by now.

[jimmy2x2x]

Driverman, Driverman can he spam? Of course he can.

[newmanfamilyvlogs]

There was a thread a while back where someone's phantom presses apparently ended up being a ground wire at just the right length to act as an antenna for a nearby radio transmitter, picking up just enough RF energy to occasionally trip the sensor on the ipac.. the solution was to change the length of the ground wire (essentially changing the tuning frequency). Sometimes it's the weirdest things that end up being solutions.

The mundane answers are to inspect the switches themselves..make sure they aren't shorting out. Look for loose wires that might be swinging during gameplay.

Open up Notepad and leave it running a few hours untouched. Does anything show up? Do the same thing put wiggle your cab around a little (as if people were playing on it hard). Trigger it then? If it doesn't then  you're starting to rule out something physical as the source.

Randomly press buttons/joystick on each player, while in notepad. Do a character search for the buttons assigned to other players. Anything show up that it shouldn't? Maybe it's a wiring problem. Maybe the IPAC is damaged.
 

[vagabound]

There was a thread a while back where someone's phantom presses apparently ended up being a ground wire at just the right length to act as an antenna for a nearby radio transmitter, picking up just enough RF energy to occasionally trip the sensor on the ipac.. the solution was to change the length of the ground wire (essentially changing the tuning frequency). Sometimes it's the weirdest things that end up being solutions.

I would expect PC ports to have some threshold and minimum operational voltage above the minuscule amount that can be induced by EM radiation. What "sensor" is there on the IPAC? Are you suggesting electric current was induced in some "sensor",  in some wire going from IPAC to control panel, or along USB cable going from IPAC to computer?


It was mentioned the problem seem to manifest only with MAME, but in any case why would you think it would be the weirdest thing when all you have to do to get ghost input is to enable "syncrefresh"? What's weird is that everyone should want to have "syncrefresh" enabled if they want to have smooth scroll, so the real mystery to me is why no one seem to be aware of this very obvious bug persisting in MAME for the last ten years?

Go ahead, take the latest MAME.143, for example, and run 'Bank Panic' with default settings. Hold left or right and fire quickly with just one button, notice how input does not overflow, no ghost actions, but there is terrible tearing, waving and choppiness in the scroll. Now, run the game again but this time enable "syncrefresh", and to make it work in this version you also have to disable throttle, then try the same thing again and you should see how input lags quite a bit and after only 10-20 seconds if you let go from the controls it starts to play all by itself. Yes? No?

[Roo5676]

Thanks for the responses - I haven't had time to test more thoroughly lately.

To answer the questions: I'm using the 64-bit command line version of MAME .142 on Windows 7.  I know I have vsync turned on; I don't think I've touched synchrefresh.  But I've never had any issues in single player, or indeed in any other circumstance other than I described originally.

It is a tough thing to test, though.  A friend and I later tried to duplicate the issue in NBA Jam with the two of us each controlling two players and pressing as many buttons as we could at once and weren't able to.  Yet when we were playing 4-player for real it was happening consistently enough over a period of 1-2 hours.  Probably happened 10+ times to me (as Player 1) in that time.

I will try to play with it more tonight and try out some of the ideas mentioned.

[Roo5676]

Ok, I tried out the notepad idea.  No input when just left sitting there or when shaking it.  No stray input from any one player when using a different player's buttons.  I don't think it's something physical.  Besides, this thing was built by pros who make several control panels a week.  I'm not saying it would be impossible, but I trust their build more than I would trust my own (since I don't know anything about wiring) and it's been rock solid except for this one rare problem.

I can confirm my original settings were:

 - waitvsync: 1
 - syncrefresh: 0
 - throttle: 1

I had originally enabled vsync because I saw noticeable screen tearing otherwise.  The other two are defaults.  I cannot duplicate the lag problems that vagabound is describing, though, even with syncrefresh enabled and throttle disabled as mentioned.  I tried Bank Panic and 1941 and could not see any difference that either (or both together) of the settings made.  Both games ran smoothly with perfect input.  Note that I'm running on a brand new 3.6 ghz dual core i3 if that matters - maybe it would affect my results with these settings compared to an older PC.

Even if I had been able to duplicate it, it does not sound at all like what I'm experiencing.  We're talking one random button press every minute or so, not "input lags quite a bit and after only 10-20 seconds if you let go from the controls it starts to play all by itself".


By the way, forgot to mention that I'm shocked that Twin Galaxies allows any emulated games for records.  I thought those guys were pretty hardcore about having original, unmodified hardware.

[newmanfamilyvlogs]

vagabound was the newest nickname of a guy who's historically been about 30% accurate and 70% flaming ---That which is odiferous and causeth plants to grow---. He's regularly banned on the boards. Usually he's safe to read, think about, but otherwise ignore.

Twin Galaxies has a special category for emulated high scores.

I wonder if you've got a 'shfit' key somewhere you don't know is set up. I'm about half-stumped at this point.

[hoffy84]

I know this is an old thread, but it was never resolved,

So I PM'd ROO5676 to see if he ever got it fixed, and he said no. I was having the same problem as well, and I am pretty sure I resolved it (at least on mine).

So I am just posting this, in hopes that if someone else out there is having similar issues then maybe this will help....

Roo is using an IPAC4, which I do not know much about, but I will tell about my setup, and perhaps things can snowball off that:

Attached is a picture of my control panel, and as you can see, I have 7 joysticks, and a sh*tload of buttons. So the encoder I went with is a Hagstrom KEUSB108, since there are a lot of inputs availbale, and of course no possible ghosting. I have mapped it several times, using keyboard only (including SHIFT + keys, bc I was running out of inputs). That could have been one problem in itself (using SHIFT).
I then realized that my encoder had a "JOYSTICK" tab, that you could map most of those inputs to (4) POV hats and 64 JS button assignments. (I do not know if the IPAC4 has the same feature). (Attached is picture of my Hagstrom KEUSB108 GUI screenshots)

 So I remapped my main 4 joysticks to the 4 POV hats, and remapped most of my buttons to the JS buttons 1 - 32 (BTW the Mame sees those as 0 - 31) Also I have 33 - 64 JS buttons, but Mame doesn't see those for some reason.

So combined with that, whatever buttons were left over to assign, I adhered to HiTek's "Optimal Key Layout". (picture attached)

Lastly, When I set up the General Controls in the MAME Tab, ANYTHING that I would not be using I blanked out. (Things such as Analog Paddle , Player 1 button 16, and so on). I think this is important, because by default those functions are set up as what MAME determines are default keys on your keyboard. (So even though you reassigned it in your encoder, MAME, by default, sees it as the original key-press, and that may trigger one little stray movement during game-play.

I tested on Mortal Kombat (by myself) and interference is completely gone. I still have not tested a 4-player simultaneous game (Which will be the REAL test), so I will post my findings next time my buddies come over and we'll try Turtles in Time, Simpsons, NBA Jam, etc.

For now, if anyone is having the same issue, then I hope this helps narrow things down for you, and Roo, hopefully your IPAC4 lets you assign JS inputs. If not, then there has to be some plug-in that allows you to do so.