Cassettes in the 1970s were great for recording music off FM radio and also for making copies of LPs you owned (or borrowed) that you could play in the car. I bought very few if any prerecorded cassettes as the sound quality didn't seem as good as LPs. Dolby and other forms of noise reduction were big for getting rid of "tape hiss." Sometimes the cassette deck would mangle the tape "bandsalad" I have heard it called. Cassettes with screws were preferred so you could fix a mangled tape. C-90 length tapes were the optimum since they could easily hold an LP and seemed a bit more robust than the C-120s. John Peel was the DJ I listened to and recorded from the most off the Beeb back in the UK.