Flat Packs

Rick Bensene rickb at bensene.com
Sat Aug 9 20:07:29 CDT 2008

I've only come across two electronic calculators that use flatpack IC's.

In 1965, Victor Comptometer made an attempt to build a fully-electronic
desktop electronic calculator, called the Victor 3900, that proved to
push the state of the art just a little too far.  The 3900 used
round-case flat-pack IC's, with 22 leads, with spot-weld type technology
used to connect the leads to the circuit traces on the circuit board.
Unfortunately, the yields of the ICs were not very high, and there were
lots of infant mortality problems with the chips dying once the machines
were in the customer's hands.  The machine, had it been successful,
would have put Victor in the enviable position of making a massive jump
in technology over the electronics used by anyone else at the time, and
would have kept them ahead of the game for quite a long time.  There's
some information on the Old Calculator Museum website exhibit on the
Victor 14-322 (a machine made significantly later using very
conventional technology) at

In around 1970, the Casio AL-2000
(http://oldcalculatormuseum.com/casal2k.html), an early small-scale MOS
IC-based programmable (in very limited form) calculator, used two 24-pin
flat-pack integrated circuits made by Philco, in ceramic bases with gold
lids and leads in the arithmetic logic unit.  These are medium-scale
devices, one of which (part number SC-1770) is a bit-serial adder adder,
and the other chip (SC1771) is a complimenter IC, date coded in late
1968 to early 1969.  The chips are surface mounted, again using some
kind of spot-welding to connect the leads of the device to the traces on
the circuit board.

Rick Bensene
The Old Calculator Museum

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