Popular Electronics 1/1975: An under $90 Scientific Calculator

[Karl-Ludwig Butte]

Dear all,

Popular Electronics issue #1, 1975 is famous for its presentation of the Altair 8800 computer. But on page 53 there is another interesting article for us calculator-centric folks: An under $90 Scientific Calculator.

The article describes the scematics and the construction of a scientific calculator with 10 digits and double nested paranthesis. It even prints the PCB layout. But - and this is a BIG but - it does not name the type of the two main integrated circuits. The reader should buy the complete building kit from Network Research Corp., 27 Eagle St.,Spring Valley, NY 10977.

All this is 41 years ago. Does anyone of you perhaps know which MOS ICs (IC1 & IC2) were built into this calculator or even has this model in his/her collection?

Best regards

Karl

[Didier Lachieze]

The ICs are the MOS MCS 2525 & MCS 2526 (used also on the Commodore SR 36 & 1400 and other calculators at that time), the calculator described in this article is the Melcor 535, I have one as well as the two Commodore.

Two others similar articles have been published in Popular Electronics:

• Martin Meyer, Build The 'Senior Scientist' Calculator, Popular Electronics, Oct. 1975, p. 33 which describes how to build a calculator similar to the Melcor 655 which was sold as a kit.
• Martin Meyer, Now You Can Build A Scientific Programmable Calculator, Popular Electronics, May 1976, p. 36. This document includes at the beginning the article "Here Are The New Programmable Calculators"
  

[Karl-Ludwig Butte]

Hi Didier,

thank you very much for your comprehensive reply and the additional articles.

Best regards

Karl