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
Calculator watch appointments, names, addresses, and phone numbers. Mass-produced calculator watches appeared in the early 1980s, with the most being produced in the middle of the decade, The future of the calculator watch as a practical and useful electronic device has been impacted by the introduction of PDAs, mobile phones, and other powerful multi-functional compact computing devices. As a result, many calculator watches are used for aesthetic purposes. Calculator watch A calculator watch is a digital watch with a built in calculator, usually including buttons on the watch face. Calculator watches were first introduced in the 1970s and continue to be produced,