Druin's Interface

[SeaMonkey]

It seems to me that you were saying there was a problem with Druin's rotary interface.

I can't get it mess up for me and I was wondering if you could tell me what to try to get it to mess up, and what exactly the problem is with it.

Doesn't the druin board just send a left of right key stroke for every click?

[Druin]

I can't get it mess up for me

I think this is great news personally!

I think people are just saying that the way the whole rotary thing works by the nature of mame is the mess-up, leading to inherent glitches such as over or under-turning of the character because MAME treats the inputs somewhat inaccurately.  The original arcade hardware had 12 distinct inputs for the rotary position so no matter how sloppy you do the rotation, once it lands on a position the game knows exactly where it is and can adjust the character.  With mame, even if you turn the joystick perfectly, the emulator itself seems to sometimes overshoot or miss the input entirely (you can experiment with pressing a keyboard instead of using the hardware and see how accurate mame is)  so the character will just start whizzing around and stop like a roulette wheel and you may think you turned 3 times, but you end up 2 or 4 or something unexpected.

So that's the issue as I see it, and we're stuck with it unless we want to use up that many distinct keyboard switches and hack mame to accept the inputs discretely instead of relatively (I forget if there's already a hack like that but if so, I think it is also imperfect as far as MAME goes in some games).

I don't think this affects gameplay, back when I first built the device in 2000, I played and beat Ikari no problem (never could do it in the arcade but I also didn't have infinite quarters).  It's just an authenticity issue.

[SeaMonkey]

Druin, great device by the way.

Let me ask you this. Does the board buffer the keyboard inputs, or does it send a left or a right immediately?

If I remember that is where the discussion went last time I saw it, but, like I say, I can't make your board fail when I try.

[rdagger]

A problem I noticed with the rotary interface I made and my IPAC, is that it does not work well on slower computers.  It makes lots of mistakes on my old 300 MHz Pentium laptop.  However, as soon as you get above 1 GHz the problems go away. 

Also I found that if the LS-30 are not properly grounded, static electricity can interfer with the rotary interface.

[Druin]

Let me ask you this. Does the board buffer the keyboard inputs, or does it send a left or a right immediately?

It doesn't buffer, which is a decision I made back when I was doing tryouts originally.  I noticed that if you hold down a rotation input, the character keeps repeating that direction instead of accepting it as a one time press, and I noticed mame wasn't 100% accurate with what the user was pressing, so I thought why go so far as to accurately count inputs and assert that many outputs when mame will only round it off anyway.

The other issue was at the speed that a user can rotate during gameplay, compared to the amount of time the output is asserted to register keystrokes, coupled with the MAME input rounding (turning keystrokes into analog action), it seemed redundant, if I did count say 10 inputs and then go on to send 10 outputs, it would look almost like a continuous keypress anyway, plus mame would treat it as such.

So however it exactly evolved, I ended up with what I have today and to me it's optimal for what we have to work with.  If you're aiming at 12:00 on the screen and you need to aim down at 6:00, you're going to twist so fast that mame sees a continuous keypress instead of 6 pulses sent.  Or at least if it does see the 6 pulses, it will treat them as a long stretch of an analog motion.

If you run a game and just sit there on the keyboard pressing the rotate right key at a slow rate like once or twice a second, eventually it'll move 2 notches on one hit, or not even move at all for that hit. 

[Druin]

A problem I noticed with the rotary interface I made and my IPAC, is that it does not work well on slower computers.

[Lilwolf]

Well...

[SeaMonkey]

Well...

[rdagger]

What kind of mistakes did it make, and how often?