* - The late Kashio Tadao, founder of Casio Computer Co., Ltd., was born in Kureta-mura (now Nankoku City) in Kochi Prefecture, Japan, in 1917. In 1923, after the Great Kanto Earthquake, the whole Kashio family moved to Tokyo at the invitation of an uncle working there.
After graduating from high school, Tadao began working as an apprentice to a lathe operator. The factory owner recognized Tadao's skill and encouraged him to begin studies at Waseda Koshu Gakko (now Waseda University), while still working at the factory.
He gained experience in a variety of jobs, making pots, pans, and bicycle generator lamps, and soon earned a reputation for himself and received subcontracts to process parts.

* - April 1946: Tadao Kashio founds Kashio Seisakujo. (樫尾製作所) Tadao Kashio in his day as a lathe worker.
* - Kashio Seisakujo was a small subcontractor factory that made microscope parts and gears.
Kashio Seisakujo was a small subcontractor factory that made microscope parts and gears. Tadao had three younger brothers, Toshio, Kazuo, and Yukio. Toshio initially worked at the Tokyo office of the Ministry of Communications (now NTT) as a technician, building and equipping telegraph and telephone facilities. However, when Toshio saw how Tadao was toiling every day at his job, he began to wonder if he could come up with something to help his older brother with his career. As a child, the thoughtful Toshio had admired Edison, and told his family that he wanted to become an inventor when he grew up. With his extensive electrical knowledge, Toshio had already achieved results in system improvement at his workplace; however he decided to quit his job to go work at Kashio Seisakujo in order to really test his own abilities for innovation.
Utilizing his natural inventiveness, Toshio tried out several new ideas. One of these was “the yubiwa (finger ring) pipe.” At that time in postwar Japan, commodities were in short supply, and people smoked their cigarettes down to the very nub. For this reason, Toshio came up with a ring-mounted cigarette holder so that he could also smoke while doing his work. Tadao produced it on a lathe, and their father Shigeru went out to market it. Orders gradually began to pour in and the yubiwa pipe became a hit product soon after it was produced. The profits from this invention would later go towards the capital needed for development of a new kind of calculator.
  The Yubiwa pipe
Looking for a new product to follow the yubiwa pipe, the Kashio brothers laid eyes on foreign-made electric calculators at the first Business Show held in Ginza, Tokyo, in 1949. Most calculators at that time used mechanical gears, and there were none that employed electronic circuits like today’s devices. The main type of calculator used in Japan at that time was the hand-operated calculator, which employed gears and a hand crank. Although electric calculators using a small motor to turn the gears had already appeared overseas, they could not be manufactured in Japan, as a high level of technical expertise and special quality materials were needed in order to process the parts.
Although the electric calculator was faster than the hand-operated model, it was still much slower than calculators today, and since the gears turned at a high speed, it made a shrill noise. With his electrical knowledge, Toshio thought that he could resolve a lot of the problems by using all electrical circuits instead of mechanical parts, and decided to try to make his own calculator. Toshio used a type of electromagnet called a solenoid, and began development of an electric calculator without gears.
  Ginza street in 1949