How did old games from 8-bit era game consoles store music?
Each console had a few channels, each with a different "instrument" built into hardware and set in stone. It's not like today where you literally just record the audio. It was more like sheet music that the console reads and plays. Sometimes they had to shuffle things around the different channels to make things work. It was kind of like how vector graphics are to a bitmap.

I don't think we're not supposed to do video links here, but this video explains it far better than in text:

https://www.youtube.com/watch?v=q_3d1x2VPxk