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
Braun (company) producing film slide projectors, a mainstay of its business for the next forty years. By 1956, Braun was marketing the first fully automatic tray film slide projector, the PA 1. Braun AG slide projectors all utilized a linear or straight tray as opposed to a round-tray design, which allowed the projector to remain small and compact. The 1950s also marked the beginning of the product that Braun is most known for today: the electric shaver. The S 50 was the first electric shaver from Braun. The shaver was designed in 1938, but World War II delayed its introduction until 1951.