I have recently heard about recording video games' binary codes from radio programmes which was quite popular several decades ago.
The computer name was ZX Spectrum. The general idea behind the process was that you had to turn on recording when the radio program started. The whole radio program sounded like a high-pithced noise to human ear but overall it could be decoded to a binary file and run by ZX Spectrum.
I would like to learn about the technology which made this cool process work. As @hotpaw2 mentioned in the comment, it might be quite interesting to learn something about the modulation scheme and protocols used to transfer the programs over RF.
Lately, I learnt some basics about the signal modulation schemes, so I think I am capable of understanding general ideads behind this technology.
What are these modulation schemes and protocoles used in this particular technology? Why it usually took over 15-20 minutes to transmit the whole program over RF.