Does Kong Have Lag?

[Shamrock]

This is a question I am asking to the forums because something weird happened during Kong Klash 9. Its something I've never seen nor thought was possible.

So, during a good run of a game, and then a subsequent run, I experienced a lag input of the button i.e. when I pressed jump, it didnt jump. I thought maybe the button was having issues, so it got cleaned, and nothing happened. Then a few games later I go to press the jump button, Jumpman takes two steps AND THEN he jumps, which causes me to get hit by a barrel.

I thought "Okay, maybe I'm crazy, that has to be a fluke" but I brought it up with Daniel Solis, our head tech. This morning as he is moving Kongs around to prep for standard opening, he goes off and plays a game, and sure enough, he experiences the same phenomenon on the same cabinet. It happened to him on the right side in a non-crucial spot a few inches before the safe spot on the top right of a barrel stage. Mine happened near the first full ladder of a barrel stage, decently far on the right side.

Is there maybe something in the code that doesnt allow Jumpman to jump immediately in certain places? It isnt a button issue either, we tested voltage and it reads the moment the button is depressed. But to have Jumpman take two full steps and then jump just seems like something in the software, and this only happened on one machine. During my first good run he didnt jump at all, which leads me to believe that was input lag as well because I died to a barrel by running into it. It didnt make any sense at the time, bit looking back I can see that being an issue.

So are we crazy or is there really something to a sort of input lag?

[Flobeamer1922]

From some testing I’ve done in MAME using frame advance, it seems that Donkey Kong inherently has two frames of input lag.

[Sock Master]

This scenario is technically not possible in Donkey Kong's program code and hardware...  unless it's the button itself that is faulty and it's not making contact/closing the circuit right away.

The program code that handles registering jump button input runs once per game frame and it only lets a jump button input through for one frame for every push of the button.   If you press the button and hold it down, the game code will only receive a signal that the jump button was pressed for one frame - the moment the button made contact.
That's why if you press the button before Jumpman is done landing a previous jump he won't jump after he lands, even if the button was held down.  The code ignores the button until you let go and press it again.


If we're talking MAME or some other emulation, the story is different as there can be any number of lag frames.  I've seen 60-in-1 boards that don't show anything happening on the screen until several frames after pushing the joystick/button.

[Scoundrl]

Make sure the button wiring is correct. This happened to me with a game once and it turned out to be wired normally closed not normally open.

[YesAffinity]

The microswitch is starting to fail.  It will become more frequent with time and/or more use.  Replace the microswitch now.

Have had an above average number of microswitches failing recently.  Joysticks, buttons, you name it.  It always starts with intermittent failure, leading to extensive troubleshooting, thinking it's something else and has been fixed, and then it keeps recurring with greater frequency.  Replace the microswitch, and that was truly the problem all along.