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
Integrated Electronics Piezo-Electric the sensor or cable. In between these two limits a functional sensor has been detected. The bias voltage is cut off by a coupling capacitor at the instrument input and only the AC signal is processed further. Piezoelectric sensors which do not possess IEPE electronics, meaning with charge output, remain reserved for applications where lowest frequencies, high operating temperatures, an extremely large dynamic range, very energy saving operation or extremely small design is required. Integrated Electronics Piezo-Electric The abbreviation IEPE stands for Integrated Electronics Piezo-Electric. It characterises a technical standard for piezoelectric sensors which contain built-in impedance conversion electronics. IEPE