In the early days programs, like on other "HOME" computers were saved and loaded to/from a standard cassette recorder, this seemed to work fairly well, but on some machines a program saved on a hot day, may not load on a cold day. The clock frequency (often a simple NE555 circuit ) drifted with temprature. The Interak circuit was much better then this, using an AY-3-1015 UART, dual output and relays to switch the recorder motor on and off.
It was not until we had Floopy drives 3.5" 720Kb that we had a choice of Basics and Pascal, "C" etc. This all ran under CP/M 2.2. Which we still use, even if it's on a Compact Flash card.