HP 1663A Logic Analyzer keyboard

[Chuck Guzis]

On a sudden impulse, I put in a bid for an HP1663A logic analyzer for 
$30 and won for $29.  Just got the thing--it's essentially in like-new 
condition--not even a scratch, no CRT burn and comes with the original 
set of pods and grabbers.  Not so much as a fingerprint anywhere--even 
the line cord is clean.  Must have come from a rental place.

I've got the user and programming manuals, but that keyboard jack in the 
back has me befuddled.  It's an RJ45 modular jack with the middle 4 
positions populated.  The manual only refers to it as a "standard" 
keyboard and mouse connector.  What does that mean, exactly?  What kind 
of signals does this "standard" keyboard use?

Thanks,
Chuck