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49-way vs 4-way vs 8-way in MAME: Differences...
Tiger-Heli:
The text below is just my understanding of the problem.
BTW, also see these threads from 2003 (relates exactly to what you are asking)
http://forum.arcadecontrols.com/index.php/topic,7288.0.html
http://forum.arcadecontrols.com/index.php/topic,5854.0.html
--- Quote from: AndyWarne on April 13, 2005, 06:54:58 am ---Good (and quick!) replies, thanks.
So in fact it's the ROM which is doing the sorting-out of 8-way not MAME itself nor the Allegro code in MAME.
Andy
--- End quote ---
Well, yes and no - I think it's gone into Web-History now, but Derrick Renaud (discrete sound MAMEdev now) did some work on using relays to make an electronically switched 8-way to 4-way joystick. This was eventually converted to software and added to MAME (probably somewhere in the mid-36 or mid 35 Beta series) as what came to be known as "Sticky Mode".
I don't remember which was Sticky and which was non-Sticky, but the basic idea was:
METHOD 1:
If you are moving left and then go to a diagonal, it still reads that you are going left. When you break the diagonal and hit "up", it then changes to up until the next clean direction change.
METHOD 2:
If you are moving left and then go to a diagonal, it immediately switches to the new direction.
The problem is that in either method, it sometimes guesses wrong about what you are intending, and sends the wrong signal. PacMan is more tolerant of wrong guesses than DonkeyKong, so the ROM does have some effect, but it's definitely not the only consideration.
You could probably add some "fuzzy logic" in MAME and get it more accurate - monitor the amount of time the diagonal was pressed to determine whether a direction change was intentional or not - but this goes against the spirit of the project, so probably won't happen.
The big advantage with the 49-ways (or an analog stick) is the greater resolution allows you to make better guesses, i.e. an 8-way just knows Up and Right are pressed, and has to decide what to do. A 49-way can say Up and a little Right is pressed, so probably Up is what is intended.
But RandyT also posted that the mappings that work are not what you would analytically expect them to be.
paigeoliver:
Also, I am not sure how useful sticky mode can be when Mame doesn't even know the correct joysticks for half the games. Last time I checked Mame listed dozens of 4-way games as 8-way games and several 8-way games as 4-way.
Tiger-Heli:
--- Quote from: paigeoliver on April 13, 2005, 07:38:44 am ---Also, I am not sure how useful sticky mode can be when Mame doesn't even know the correct joysticks for half the games. Last time I checked Mame listed dozens of 4-way games as 8-way games and several 8-way games as 4-way.
--- End quote ---
Yes, there is that as well.
RandyT:
--- Quote from: AndyWarne on April 13, 2005, 06:09:21 am ---... I think I am missing something.
Do I need to add electronic division of the analog circle into 4 or 8 sectors? I don't think I do, but will do so if there is going to be a real benefit.
Andy W
--- End quote ---
This is pretty ironic, considering this post.
I guess it's only ok if you are the one knocking off someone else's ideas. This post is tantamount to you "asking permission" from the community to do so.
RandyT
AndyWarne:
For goodness sake...the thought of copying anything did not even occur to me. What do you mean by copying exactly? The concept of mapping a 49-way stick is an old one, documented in several places including here:
http://www.urebelscum.speedhost.com/49waySticks.html
I am not intending copying anything at all. When you brought out the Keywiz did I accuse you of copying the I-PAC? Of course not because you didn't. You designed an alternative product which performed a similar task to an existing one. Nothing wrong with that.
Mapping an analog stick into sectors (as opposed to a 49-way stick) is such an obvious thing to do I am sure plenty of people have thought about this before and I am sure there are sites which document this, although I have not searched. Nothing new here at all and certainly nothing copied from yourself.
Andy