You should read about the development of a Ludum Dare entry called Ponk.
It’s a C64 version of Pong, developed on a real C64 with only a C2N datasette to save code. Back in the day I was lucky enough to have a 1541-II disk drive. I can’t imagine how painful it must have been working with a slow and unreliable cassette.
In the end he couldn’t transfer his game to a PC so he had to take screenshots of his game and OCR them, hand checking every byte. I did something similar about 20 years ago when I was tinkering with a C64 to Amiga cable and needed to somehow transfer a C64 programme from the Amiga to the C64 to do the transfer .. Painful.