Desk Electronic Calculators

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Casio 121K

Casio 121K

Casio 121K

Display is 12 Nixie type tubes.

4-function.

Semiconductors - Fairchild LSI ICs SL-35021, SL-35022, SL-35023, SL-35024, date coded to the beginning of 1971, & 21 MSI ICs on 2 boards 10" x 5 1/2".

250 mm wide, 290 mm deep, 80 mm high (10" x 11.5" x 3.5"), 2 1/2 Kg (5.5 lbs.).

Made in Japan.

Similar electronics to the Casio AS-C but a completely different looking calculator.

Casio have always been at the forefront of the development of electronic calculators.
Fairchild, one of the giants of the semiconductor world at this time, were only briefly involved with calculator integrated circuits.

The 4 large ICs among a scattering of small ones illustrates the growing takeover of the electronic functions by Large Scale Integrated-Circuits (LSI) at this time.

Inside Casio 121K

With the cover removed. On the right is the top circuit board, the bottom board is underneath it.

Casio 121K circuit boards

The two circuit boards removed. The four Fairchild LSI chips are on the board on the left.

Vintage Calculators

© Text & photographs copyright Nigel Tout   2000-2017  except where noted otherwise.