The C64 Cass Interface makes it possible to store and reload data on a normal HiFi cassette recorder. For this purpose the data is processed in the interface before it is sent to the C64. It doesn't matter if the data was previously saved from a datasette or a cassette recorder. The interface can also take over the motor control of the cassette recorder if it has the appropriate function. In addition, you can switch between the recorder and the datasette simply by using a switch on the interface.