Help me map this button on a somewhat non-standard bartop control panel

[spedinfargo]

Building a bartop for my buddy - standard Degenatron from Haruman.  Because I wanted to have two joysticks (Robotron) and if I'm doing two joysticks I might as well have a some buttons for the second player but I still want to have 6 buttons for player 1... well, I ended up with kind of a mess but it works pretty well and it's comfortable enough and I think it'll be fine for the 99% of the time he'll be playing solo.

Anyway.  Attached is a diagram but I ended up with this:
P1:  Joystick + 6 buttons
P2:  Joystick + 4 buttons

Left and Right Pinball buttons
Front:  Mystery button, Player 1 start, Player 2 start.

So my question:  what should I map to the extra button?  Any ideas?  Is there a benefit for maybe button 7 or 8 for P1 or maybe 5-8 for P2?

I'm using an Xarcade controller for the guts if that matters...

[harveybirdman]

add coin....

but why do you want Pinball on this thing?

[zallax]

Extra button could be a Pause or Exit.

Button 7 on is only beneficial for a NEOGEO if made inline with maybe the bottom row.  I would say buttons 5 & 6 are beneficial on P2 for games like Street Fighter and such.

[JDFan]

If going to have 2 player - I'd add a 5th and 6th player 2 button so you can play the fighting games with 2 players and wire them in tandem with the pinball buttons (since you will not be using both sets at the same time might as well have both the pinball buttons and player 2 buttons 5 and 6 wired together so you only use 2 inputs for the 4 buttons. (and might actually add a second set of pinball buttons since most pinball emulations use 2 sets of buttons and wire them in tandem with player 2 buttons 3 and 4 also - freeing up a couple more inputs so you have the ones needed for your coin buttons.

So instead have 2 player set up with 6 buttons each 2 start and 2 coin buttons ( 8 inputs for the 2 joys and 12 for the buttons and 4 for the start and coin inputs = 24 inputs ) which IIRC leaves 4 inputs for the pinball buttons if the xarcade controller supports 28 inputs or as mentioned wire the pinball buttons to the same inputs as player 2 buttons if it has fewer than 28 inputs.

[spedinfargo]

Thanks for the responses and ideas!

I tried to figure out a way for 6 buttons for each person - there just ain't enough room.  I don't think he'll be playing any head-to-head fighting games, but I wanted six buttons on the P1 in case he wants to play solo fighting games.  I did want at least one or two buttons for P2, though, especially for Joust, Gauntlet... theoretically he can go 2 player Track and Field, even though the buttons would be terrible for the second player.

Pinball buttons were really only put there for things like coin in, exit, pause, etc.  I thought that the left PB was supposed to be coin in, but not sure.  Regardless I guess it makes most sense to make that third button on the front to be the Coin 1 button.  That's what I'll probably go and and do...

[paigeoliver]

I would drop the player 2 buttons altogether. Better to have a machine that does 10 things well than it is to have one that does 20 things poorly.

[spedinfargo]

I would drop the player 2 buttons altogether. Better to have a machine that does 10 things well than it is to have one that does 20 things poorly.

Too late unfortunately - final holes are already drilled and buttons are in place.  Finished product (except the aforementioned extra button not hooked up yet).

I disagree with dropping the 2p buttons altogether, though.  I thought about it a lot and the solo control panel that Haruman provides didn't do it for me (I had him send me a couple uncut ones as well for me to play around wtih).  At the least I wanted:  Robotron (two joysticks), Joust (second joystick and a couple buttons) and Gauntlet (second joystick and a couple buttons).  That second player stuff will probably never get used very much but didn't want to exclude all of those games altogether...  He's mostly into early 80s arcade games.