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News Archive - Introducing Electronic Arrays' S-129 Two-Chip Calculator Chip Set


Electronic Arrays New S-129 2-Chip Calculator Chip Set Introduction
Radio-Electronics Magazine, April, 1973

An article introducing the Electronic Arrays' new S-129 two-chip calculator chip set.

The S-129 is Electronic Arrays' (EA) next generation of its calculator chip sets, beginning with the S-100 six-chip calculator chipset that was the first publically available calculator chipset, with all prior calculator LSI integrated circuits being proprietary developments fabricated exclusively for calculator companies. EA first started with six chips, the five, then four, then two, and finally they produced a single chip calculator IC.

The S-129 chips consist of one 40-pin device(EA 7023), and another 28-pin device(EA 7022). The chip set combines to provide the functionality of a twelve-digit calculator with four functions and a percentage function, as well as an accumulating memory register. The chip set uses fixed decimal point positioning, with the number of digits behind the decimal point set by an external switch. The chip set provides its own clock generator, power-on clear, keyboard scanning, and display generator for multiplexed seven-segment display devices.

This chip set is used in a the SCM Marchant 221 calculator that is in the museum's collection but is not yet documented on website. The museum's Marchant 221 calculator is likely a rather early production unit because the date codes on the chips are from the March/April timeframe in 1973, and given publication leadtimes, it's likely that the chip set was shipping to customers in the late part of 1972.

 
The SCM Marchant 221 calculator and circuit board showing the Electronic Arrays S-129 chip set