Is it really so, that the USA controllers have physically only one button? If they have two buttons that both act same way it should be easy to convert them to 2-button joysticks. Only one wire needs to go to different pin.
The Atari 2600 controller has only one physical button.
...or you can always take a Sega Master System pad and adapt it for MSX use. It's just a matter of barely change 2 wires, then you'll be able to use the 2nd button.
The Genesis pad, as the SMS one, only support 1 button; but with some rewiring, slightly more difficult than the first, you'll also get the 2nd button working on MSX.
Last; but not least, remember that the X68000 pads are compatible with MSX. Although here in Europe, is easier to find MSX joysticks/pads (I got mine with a SMS adapted pad
); maybe there in the states, the X6800 pads are more common, don't know...
meant *F1 spirit and gradius being the obvious outliers... oh well...
