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
Programmable calculator now available. It is installed via a cable or IrDA connection with a computer. RPL is a special Forth-like programming language used by Hewlett- Packard in its high range devices. The first device with RPL calculator was the HP-28C released in 1987. The language PPL was introduced with the HP Prime calculator and is much like Pascal An on-board (i.e. right on the calculator) assembler for TI 89 and related calculators was announced and released in 2014. Machine language programming was often discouraged on early calculator models; however, dedicated platform hackers discovered ways to bypass the built-in interpreters on some