I spent some time with the NCR minis at AT&T and a soon to bankrupt major
airline.
The premier box was the 3600, which was probably the box that the original
poster described as "2 refrigerators", or some such...it was about that big
or bigger. As I recall, it had up to 32 i486 processors (I vaugly recall a
Pentium upgrade, and maybe a PPro one) and used some Teradata interconnect
IP. They were touted as "data warehouse" boxes, and were usually used for
some big DB app. Million dollar boxes. Ran pretty bog standard SVR4.
I never saw a place to plug a keyboard and mouse into one of these...
Then there were the 3550, 3500 and 3450 (at least...I think there were
more). Proprietary Pentium multiprocessor, Microchannel minis...well
constructed and fast for the time. Kinda sorta like Sequents. They ran
SVR4 or SVR3.2, and I've seen at least one of them run NT 3.1.
Someone even thought about porting Linux to the thing:
http://www.anime.net/~goemon/linux-3550/. I shall not hold my breath.
All of this stuff was superceeded by the Worldmark line, which was pretty
much standard multiproc Intel stuff with an NCR badge.