NESpad compatibilty

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I tried to use NESpad with teensy3 and it doesn't work. I know there is two 
things which may be reason for not working.

Background googling:
"At first I thought how could they possibly mess up a shift register! The only 
electronics inside the NES004 controller is the one chip. Then I opened a 
NES004E controller and saw more. There are pull up resistors on the clock and 
latch lines. Apparently the Mattel NES (and possibly all European NES) use open 
drain outputs. The NES can pull those lines low, but needs the pull up 
resistors to set the lines high. That means a European controller will work on 
a USA system, but not the other way around. The dog bone controller also 
includes pull ups."

Questions:
Does NES gamepads work with 3.3V? NES-004E which I use is built with HD14021BP, 
which supports 3-18V. Is anyone tested this?

Does NESpad support all gamepad versions? Do I need to setup input line to use 
pull-up resistor?

Original issue reported on code.google.com by [email protected] on 9 Oct 2013 at 6:19