On Mon, 20 Dec 2010, Rick Bensene wrote:
Friden EC-132s with serial numbers 3902 and above were
three-counter,
with earlier machines four-counter
I've just checked our two machines (the third was from a friend), these
are the serial numbers on the bottom front of the base (and also somewhere
inside the machine):
* 132-33797
* 132-4638-1910
There were some wiring differences between the
machines, which did limit
the compatibility of boardsets (e.g., not a good idea to put a
four-counter boardset in a calculator made with a three-counter
boardset, but there are specifics in the service bulletins that give a
matrix of compatibility between the machines based on the individual
board pairs.
I need to scan these service bulletins and put them online on the museum
website, but haven't gotten to it yet.
The Fridens are very interesting machines, I'm always impressed by the
ingenuity of the designers of early electronic calculators. The Diehl
Combitron series is another example, clearly bearing the hallmarks of
Stanley Frankel.
Christian