20 Dec
2010
20 Dec
'10
9:50 a.m.
I wrote:
manufacturing
To which Christian replied:
perform the
math operations. After the 130 was introduced, in the
process of developing the EC-132 (which added square root), it was
realized that all of the functionality could be done with three
counters
rather than four, and a rework was done of the
EC-130 boardsets to
use
> this realization to reduce the part count, and thus the cost. A few
EC-132's were also made with the four-counter
architecture,
but soon into production the EC-132 was also
changed to the
three-counter design. Each of the three counters had a slightly
different logic design.
I think that this claim is wrong as we have repaired
three EC-132s
some
weeks ago, and all have four counters (A, B, C and D),
they are
clearly
visible and marked on the PCBs. The machines also had
very different
serial numbers.
Even the boards on your site
(http://oldcalculatormuseum.com/friden132.html)
show the four-register version although you've labelled them "three
register architecture". You'll see that the test connectors at the top
of
the sandwich-PCB have marking like A->B, A->D, B->C etc., and also ADV
A and ADV D (advance A resp. D).
The four counters are built all the same way, i.e. the flip-flop
with
2N2635. They differ slightly in the logic driving the
flip-flop
drivers,
the B and C can't shift, and D shifts in the inverse direction of A
(it's
more like a rotate with "top" bit inversed and fed back to the bottom
FF).
I will double check the photos of the boardsets in the EC-132 exhibit.
The photos were from a spare boarset that I have, and I may have
misidentified it. Thanks for pointing this out.
The information relating to the different architectures I provided was
taken from Friden's internal service bulletins, which I have copies of.
Friden EC-130s with serial number 8500 and above were three-counter
machines. Machines prior to #8500 were four-counter machines.
Friden EC-132s with serial numbers 3902 and above were three-counter,
with earlier machines four-counter
I have seen both EC-130's and EC-132's with both architectures. I have
three EC-132's, one of which is SN 1984, and it's definitely a
four-counter machine, while the other two (SN 10663 and 11945) are
definitely three-counter machines.
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.
-Rick