Apparently some keyboards have a circuit to switch to the older format when they detect the right signal. I suspect newer keyboards will, or have, left this out since the technology is dying fast.
Folks, I had an idea that the Duck might work with old computers, especially those used for Point of Sale systems which still use PS-2 keyboard connectors. I dug up several old PS-2 to USB converters and tried them, but no joy. The PS-2 keyboard communications scheme is different than the USB method. It may be possible to write drivers to make the conversion. -R