the one at WH was directly connected to a vax 11/780, no paper tape either.
so that now finally explains why /dev/cat was write only, it was substituted
for a paper tape reader. it was always a curiosity that you could write
to it, yet never read it (i.e. get a status). a "cat /dev/cat" would
get you a "cat: cannot open /dev/cat" while a "cat /some/file >
would succeed, but act like you used /dev/null instead
(as /some/file was not valid phototypeseter input)
From: Doug McIlroy
The wikipedia description
seems pretty accurate although I have never seen the beast myself.
I can confirm the wikipedia description. At Bell Labs, however, we
did not use paper tape input. As soon as the machine arrived, Joe
Ossanna bypassed the tape reader so the C/A/T could be driven
directly from the PDP-11. The manufacturer was astonished.
The only operational difficulty we had was with the separate
developer. If you didn't hand feed the end of the paper perfectly
straight into that machine, the paper would tear. Joe Condon
fixed that by arranging for the canister to sit on rollers so
it could give when the paper pulled sideways.
The first technical paper that came off the C/A/T drew a query
from the journal editor, who'd never seen a phototypeset
manuscript before: had it been published elsewhere?