HP-HIL keyboards with PS/2 connectors

Years ago I bought two HP 9000/715s. I've barely done anything with them, so I don't remember for sure if they even came with keyboards. That unit's keyboards are supposed to be HP-HIL, and I know there was a breakout box to use a PS/2 *connector* on such a keyboard; but I'm wondering about the particulars of that. I have run across one HP keyboard in my stash, which has a PS/2 connector. It only partially works on a PC -- certain keys don't register at all. What I'd like to know is: is it certain that this is just a broken beige box PC keyboard? The alternative I'm pondering is that it's really an HP-HIL keyboard with a PS/2 connector that just coincidentally seems to partially work on a PC. That's unlikely, I know, but I just want confirmation to rule it out.