VT131 needs keyboard help

Another weekend project of mine has been working on a VT131 terminal. The terminal seems to work fine when receiving data. The terminal always powers up with a "4" in the corner (keyboard error?). Typing characters on the keyboard will give no response from either the terminal, or the system to which it's connected. The lights flash (all at once), and the speaker beeps when power is applied to the terminal. No lights are ever activated afterwards, though. Having taken apart the keyboard, it does have an empty socket for a DIP. Anyone know what this is? Is it possible that this is a "lookalike" keyboard? Did DEC make different models for different VT100 terminals -- were they compatible? If this is an authentic DEC keyboard, will it be marked as such somewhere? If so, how? The key layout _looks_ like VT100, but... The reason I'm asking about the brand is that there was another terminal at the junk yard, completely trashed, which looked like a VT100, but had a completely different branding. I forget the brand right off, but I'm afraid I may have picked up the keyboard for the dead terminal, and that it may not be compatible at all. Failing a way to positively identify the keyboard, are there any common modes of failure along these lines? Also, I'm guessing at this point that the terminal is in good shape. Does anyone know where to get a keyboard? Chris Christopher Smith, Perl Developer Amdocs - Champaign, IL /usr/bin/perl -e ' print((~"\x95\xc4\xe3"^"Just Another Perl Hacker.")."\x08!\n"); '