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Suzo- Happ PC Arcade Spinner? Plug and Play?
RandyT:
I might as well add something to this thread now that it has re-surfaced. As a result of the discussion with Derrick about how MAME handles input, the TurboTwist 2, High-Low, EIectric ICE Trackball and all other optical interfaces shipping from GGG are now backspin-free, with no changes whatsoever required by the user to the OS. In order to maintain the high-speed polling of the optical sensors, I opted against having this as a user-configurable option. It is automatically disabled by systems with higher poll rates enabled anyway.
Based on the way MAME deals with input now, capping the outputs has a practical zero negative effect, and high polling rates have a practical zero positive effect. An 8ms poll rate at +/-127 position offsets is extremely fast movement (about 13 revolutions per second before backspin would occur!), and is impossible to maintain by a human hand or ever be an issue while playing. The only time an overflow would really come into play is at the moment of initial acceleration when one really tried to "flick" the knob to spin it fast. Derrick has been telling me, if I am understanding correctly, that MAME doesn't actually poll the hardware but once every 16ms, or once per frame refresh. In cases where the original hardware expects smaller chunks of data to be received more frequently, MAME then divides up the movement data it received at the last poll and then uses a sort of smoothing algorithm to feed the data to the original code at a rate it would expect. It should also be noted that there is no way for any spinner interface to prevent backspin at the level of the actual game. This is strictly a function of the interaction between MAME, the OS and the original game code / hardware emulation. In other words, if you could make the original game backspin, as you could with Tempest, then you would be able to do it no matter which spinner you used. Otherwise, you would not have true emulation.
So the short of it is that, once the outputs are capped to prevent overflow at the initial moment of inertia when spun rapidly, extremely high poll rates are of questionable benefit. But upping the poll rate in the OS is still an option and will make it so the capping never kicks in, if one so desires.
RandyT
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