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Ipac Usb Vs, Ps/2

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RandyT:

--- Quote from: AndyWarne on September 23, 2014, 04:20:53 am ---USB wins in fighting games owing to the need for detecting complex moves involving simultaneously pressed keys whereas PS/2 is a slower serial interface.

--- End quote ---

"Slow" is an extremely relative term in the data realm.  PS/2 communicates at rates of up to 16khz, which is up to 1600 keypresses or 800 releases per second.  Considering that it's a dedicated port specifically for that one function,  it has more than enough speed for gaming controllers.  As indicated, on original hardware, any events which occur prior to the next screen blanking will be considered as having occurred simultaneously.  At that point, the original games internal code would decide priority.  However, input data is buffered by the OS, and given the time constraints, the emulation code will at some point need to stop reading data from the buffer so it can perform other tasks.  What is being discussed is the order in which these events are placed into the buffer to be read by the application.  If the system cannot guarantee the order in which data from the USB packets is placed into the buffers (and MS states it can't) then you have a possible scenario where an event can be delayed by a frame, even though it physically occurred prior to an event which was not delayed.  The same thing can happen with the "complex moves" described above, but this particular scenario could occur with either input device type.


--- Quote ---In spite of the PS/2 interface being simple at the hardware level, the data still has to get through all this lot: http://msdn.microsoft.com/en-us/library/windows/hardware/jj128267(v=vs.85).aspx

--- End quote ---

Which is still quite a bit less than an HID device.


--- Quote ---...  gone on longer than it should already. Much like the PS/2 interface itself :)

--- End quote ---

I guess we will agree to disagree on that point.

DeLuSioNal29:
To be honest, the only reason that I chose PS/2 for my encoder was that it freed up a USB port for other purposes.  I figured, hey, if there's a port there I might as well use it.  It's worked well for me.  :)

Moving forward though, the MB manufacturers now have tons of extra USB ports, so for me it's no longer an issue.   :applaud:

DeLuSioNaL29

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