From: Rick Bensene
E-mail: rickb@pail.dev.com
Hi, I have an old Japanese-made calculator, which appears to have been made sometime between 1969 and 1972. It uses all SSI (Small Scale Integration) Integrated Circuits for the logic. This is in contrast to earlier calculators which used discrete transistors (like the Wang 300-series and Friden 130/132 machines), and those that used LSI MOS IC's for brains. This machine has 101 14-pin IC's, all of which bear a logo which looks just like the Mitsubishi Motors 'diamond-star' logo. I'm assuming that these are Mitsubishi chips. There are a small assortment of different parts used. The numbers are: M5391, M5373, M5936, M5946, M5930, M5340, and M5962. I believe that these parts were made before TTL SSI IC's were available, and assume that they are probably DTL. I'm hoping that someone out there may recognize these, and be able to provide me information on function and pinouts of the IC's. The calculator works perfectly, I don't need this information for repair, I'm just curious as to how the machine works, and knowing this will help in some 'reverse engineering'. If you have any information on these old IC's, please drop me an EMail.
Rick Bensene