Casio 161
Image Courtesy Takaharu Yoshida

The Casio 161, along with stablemates Casio 120 and 121, were Casio's first foray into electronic calculators utilizing first-generation Japanese-made MOS (Metal-Oxide Semiconductor) integrated circuits. Previous Casio desktop calculators were constructed using discrete transistor circuitry. The 161 has sixteen digits of capacity, a single accumulating memory register, and offers fixed or floating decimal. It has a round-off mode, and supports negative numbers. It is a basic four-function calculator. The display is composed of individual Nixie tube display elements. Circuitry is contained on four plug-in circuit boards, populated with small- and medium-scale IC's in both metal can-type and DIP (Dual Inline Package) packages. Register storage is by dynamic shift registers. This series of calculators was introduced sometime in 1968, and was sold until at least the early 1970's. This calculator was also marketed in North America by Canadian electronics distributor Commodore, as the Commodore 1161.