>> I've successfully used LK401's on many DECstations (3100,
>> 5000/133, 5000/150, 5000/200, 5000/240, 5000/260), as well
>> as vt220's and vt320's.
>
> Someone once told me that the LK-201 successors (lk-401 &c) were
> designed so that they all powerup into LK-201 compatibility mode.
> they are plug-compatible wiht LK-201s and can be used as field
> replacements for LK-201s on vt220s, vt240s, and Vaxstations.

OK, these are definitive answers. LK401 works with any DECstations
except for MAXINE.  Because I know LK421 (handsomely small, my
favorite) is interchangable with LK401 in DEC 3000 series (TC alpha
machines), LK421 will also work with DECstations 
 
> AFAIK the only exception is the LK-501 DeskTopBus keyboard used on the
> Personal DECstations. Ted - do you know if DTB was some kind of
> external standard, like Apple's ADB, or was it purely a DEC WSE invention?

DTOP bus seems not a DEC invention.  Check and see www.NetBSD.ORG
documentation page refering to "ACCESS.bus" specification. 

Tohru Nishimura
Nara Institute of Science and Technology