The format is very simple, basically a square wave with different pulse widths for 1s and 0s [1]. Spectrum software was typically sold on audio cassettes and the radio broadcasts are the exact same format, typically people would record the broadcasts to cassette. The loader program in ROM just copies all the data from tape (or radio) into RAM so yes any game logic would be included in that.
Comments
The format is very simple, basically a square wave with different pulse widths for 1s and 0s [1]. Spectrum software was typically sold on audio cassettes and the radio broadcasts are the exact same format, typically people would record the broadcasts to cassette. The loader program in ROM just copies all the data from tape (or radio) into RAM so yes any game logic would be included in that.
[1] https://en.m.wikipedia.org/wiki/ZX_Spectrum_software