Programmable calculator to use magnetic strips were the HP-41C and TI-59. Continuous memory does not lose its content when the calculator is switched off. With continuous memory the user can, for example, change batteries without losing the entered programs. Compact Cassettes offered a simple, inexpensive alternative to magnetic cards. Usually, an interface module, such as the Casio FA-1, was used to connect the calculator to an ordinary cassette recorder and digital data were encoded as frequency-shift keyed audio signals. Sharp and Hewlett-Packard also sold dedicated micro- or mini-cassette recorders that connected directly to the calculator. These set-ups, while being more practical and
Koyo Electronics Corporation Limited Koyo Electronics Corporation Limited Koyo Electronics (Kōyō Denki) and its subsidiary Koyo Electronics Industry (Kōyō Denshi Kōgyō), often collectively referred to as just Koyo, are Japanese electronics companies based in Kodaira, Tokyo that manufactured radios since 1955 until 1973, and now its subsidiary manufactures industrial electronics devices and factory automation control systems. Their first product was a vacuum tube radio released in 1955, and their first transistor radio was the KR-6TS-1 radio released in the spring of 1957 at the price of 14,000 yen. Through the 1960s, Koyo had manufactured and sold millions of portable transistor radios, particularly, their best-selling