Rectangular slots in the panel?
Yes.
Hmmm, one could build a whole computer using 6977s as
the active
device. ?Wouild make a heckuva glow-in-the-dark display...
You could - but keep in mind they are simply awful triodes. People are
using them as in-base UV201 subs, due to their crummy specs.
Until recently, I had a large stock of EM80 "eye" tubes - probably
enough for a 4 bit machine.
--
Will