I think it said 750 made from the PDP-8 FAQ.
That has nothing to do with how many survived.
Compare that to the thousands of PDP-8's and Tens
of thousands of PDP-11's.
One day at RCS, we went over just how many surviving PDP-12s we know
about. The number was somewhere above 20, maybe up around 25. These
numbers did not include the one just on Ebay, or the three that were
pulled out of Temple a few years back. By now, the number of survivors
might be around 30 - a fine showing for such a large machine.
There actually may be more PDP-12s out there today than there are PDP-8s
or PDP-8/Is. Certainly more than the PDP-8/S or LINC-8 machines.
William Donzelli
aw288(a)osfn.org