title: ZX spectrum loading sound
body: <p>Apologies for the vagueness of this question; I'm remembering back to the early 1980s! When I loaded programs from cassette tape into my 48k ZX Spectrum, the sound (and bar animation) was quite distinctive, and followed a fairly standard pattern for perhaps the first 10 seconds. What was it about the structure of programs that led to this standard loading approach?</p>