With the spreading popularity of the electronic desktop calculator (denshisiki takujyo keisanki in Japanese), the name was shortened for convenience to dentaku. Through the appearance of integrated circuits (IC) containing complete electronic circuits on one chip, and then large-scale integration (LSI) that further increased the level of integration, calculator manufacturing became much simpler. In 1965, many new manufacturers began to enter the calculator market due to the strong company demand for the product. As a result, Japanese calculator production continued to double each year, and in 1970 the market exceeded 100 billion yen in total value. At its peak, there were over 50 companies in the market, and this meant a period of severe competition in development and sales, called the “calculator wars.”

The production volume was set at 100,000 units per month, which was an incredibly high amount at that time. Many people inside and outside the company voiced their misgivings about this high production level, but the release of the Casio Mini resulted in an explosive hit, and production had to be raised to 200,000 units per month. Only ten months after its release, deliveries of one million units were achieved. Subsequent improvements were made to the Casio Mini, and it went on to become a huge hit, with a final production total of ten million units. Due to the success of the Casio Mini, Casio secured the number-one position among calculator manufacturers.

Main Models up to the Casio Mini

To meet the intense individual demand that was ignited by the huge success of the Casio Mini, the Hachioji Factory (now Hachioji Laboratory) went into operation alongside the Kofu Factory in June 1973. Production was also expanded to affiliated plants in Japan and overseas, and a large-scale production system was created.

The popularization of the pocket calculator, including the Casio Mini series, has a special place in the history of electronics production in Japan. The Japanese semiconductor industry, which was still in its infancy at the time, realized many advances by applying its technical capabilities to the large-scale production of pocket calculators. In this sense, pocket calculators can be seen as the pioneer that helped pave the way for the development of Japan as an electronics superpower.

However, the Japanese clock and watch industry in the mid-70s was closely integrated from the production to sales levels, making it very difficult for new manufacturers to enter the market. Casio made intensive efforts to overcome this barrier, and in October 1974 it released a computerized watch, the CASIOTRON. This watch not only showed the hours, minutes, and seconds, but also had a unique function that could automatically determine the number of days in a month.