Those BBC TV shows had the unusual feature of broadcasting software over the end credits. Just had to tape the screeching and play it back into the computer.
That was your queue to literally physically stick the box over that square on the screen and then a few minutes later during the end credits that square would turn into what would look like to the human eye just plain old static but to the sensor in the box stuck over it, it was reading it as a datastream that the software would interpret and save.
To be honestly it wasn't terribly reliable, I think we got it to work maybe once or twice in the few times they did it but was an interesting experiment by the BBC back in the 80s!
I actually tried downloading programes from the Dutch radio station back in those days - and it worked.
Can you explain this? Do you mean that BASIC programs were encoded as sound in some way, and then could be uploaded into the computer and run?
The tape would contain bleeps and blurps which would be decoded into bytes by the computer. EG this is the sound produced by an Amstrad cpc464 loading a game: https://www.youtube.com/watch?v=OvChkOHgDIo
This meant that to copy software you didn't even need a computer, just a double cassette deck.
And that by recording the credits of this BBC show to tape and playing that back into the computer you'd load some program. That's actually a brilliant idea, I wonder what kind of software they broadcasted.
Sounds (pun not intended but noticed) like steganography.
Software has even been distributed on vinyl records and flexi singles!
You could connect a domestic cassette recorder up to a BBC Micro and use to save and load software onto normal cassettes!
There were favoured devices that would give better results and better cassettes for data storage and so on.
Its all ancient history and folklore now :-)