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
North Eastern Electric Supply Company World at the time. After the First World War it took over the Cleveland and Durham Electric Power Company, the Northern Counties Electricity Supply Company, Durham County Electric Power Company, and Tees Power Station Company. It also took over the assets of the Durham Collieries Electric Power Company and the Hexham & District Supply Company following their liquidations. NESCo opened North Tees Power Station in 1921 and Dunston B Power Station in 1933. In 1927, the company moved into their new headquarters at Carliol House in Newcastle's city centre. The building was designed by Robert Burns Dick. Carliol House Ltd.