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
Comptometer The Felt & Tarrant Manufacturing Company reabsorbed the Comptograph company at the beginning of World War I The Felt & Tarrant Mfg Co became public in 1947 and changed its name to the Comptometer Corporation in 1957. In 1960, the Bell Punch Company bought the British rights to the Comptometer design and trademark, and continued its development. In 1961, Sumlock, a division of the Bell Punch Company, was renamed The Sumlock Comptometer Ltd, and began marketing the first all-electronic desktop calculator, the ANITA Mark VII. The entire calculator division of the Bell Punch Company was bought by Rockwell International in