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
Ultra Electronics Ultra Electronics Ultra Electronics Holdings () is a British company serving the defence, security, transport and energy industries. It is listed on the London Stock Exchange and is a constituent of the FTSE 250 Index. The Company was started by Teddy Rosen in 1920 as "Edward E. Rosen & Co." manufacturing high quality headphones. In 1923 the company moved to new premises at Harrow Road, London and in 1925 a new company "Ultra Electric Ltd." was formed. Ultra introduced its first mains powered wireless set in 1931. After further expansion the company moved to larger premises at Erskine Road, Chalk