IBM Model-M keyboards
Those are very old keyboards but a lot of them are still floating around. Most should work with the adapter However, due to their age and variance there is no guarantee that the one you have will work. The main problem is current consumption. The adapter is capable of supplying 200mA of current. However, at that current level the PS/2 output voltage will drop slightly (from 5.0V to around 4.8V). The Model-M keyboard has a long cable which further reduces the voltage seen at the keyboard end. This voltage (around 4.6V) is barely above the required minimal voltage of old TTL components. A slight change of condition such as the increased resistance in old cable will make the keyboard fail.
PS/2 wedge scanners should work without problem. A number of keyboard-emulating USB ones were tested and confirmed to work.
Magnetic Strip Readers (Credit Card Readers)
We have tested several magnetic strip readers and most of them do work, for example, the widely available ones from Magtek (S/N 21040140, 21073062). Be sure to configure them as keyboard mode. HID mode does not work.
We have developed our own RFID reader that is designed to work with the Adapter. Those from other vendors may or may not work.
YubiKey Security Device
Yes. Tested to work with YubiKey, a one-time password generator.
The Enter key on keypads for iOS devices
The Enter key on a keypad (either as part of a full size keyboard or as a standalone numeric keypad) generates a different keycode (0x58) than the one generated by the normal Enter key (0x28). iOS devices do not seem to handle this key correctly (if it handles it at all). Pressing this key does not do anything. As a remedy, we added a mapping in the adapter to map the that key to normal Enter key. This mapping is on by default. It can be turned off via command line. The command is “set map keypad_enter [on|off]”.