[tommyd]

I seem to recall reading that the BBC did the same for the BBC Micro, although I can't find a reference now. Waiting half an hour for a game to load just to find the tape had got corrupted right near the end ("R Tape Loading Error" on the ZX Spectrum I grew up with) was one of the aspects I less fondly remember!

[DanBC]

The BBC Micro had a port for a light pen.

There was a small rubber sucker attachment that you could stick to a TV screen, with the light pen attached. The BBC (tv station) had a programme (probably MicroLive) that would overlay a flashing block on a small section of the screen. The light pen would read that flashing and you'd have a small program.

Here's someone talking about it:

http://forums.theregister.co.uk/forum/1/2014/02/18/ian_mcnau...

The BBC (and Sinclair, and possibly Amstrad) did a lot to make computing accessible.

http://www.bbc.co.uk/news/technology-15969065

[jamesbrownuhh]

The flashing block was "4 Computer Buffs" on Channel 4 - you can see them describe the process here:

https://www.youtube.com/watch?v=wKmu68URUeI

I recall seeing a torrent of the full series a while back - I'd like to think that it's probably still possible to decode the programs even today. :)

4 Computer Buffs also transmitted some software as audio, usually over teletext pages or the test card, while the channel was off air - again, see here:

https://www.youtube.com/watch?v=T4gRgcnj8lg

One of the BBC programmes - either 'The Computer Programme' or 'Making The Most Of The Micro' transmitted a BBC Micro program as audio, too, but they intentionally kept it very short so as not to offend viewers who didn't like the noise.

That said, they lengthened the broadcast as a result of transmitting the program at 300 baud - they did tell everyone at home to make sure they typed *TAPE 3 (i.e. to crank the loading speed down to 300 baud rather than the Beeb's normal 1200 baud), presumably to strengthen the chances of some usable data actually making it through. :)

[geon]

Assuming PAL with 50Hz refreshrate (interleaved), that would be max 50 bit/s.

[marbletiles]

You might be thinking of software on ceefax: they had pages in the high numbers which contained gibberish to the viewer but which could be read by a BBC Micro with teletext adapter

[billybofh]

They also, as I remember, used to broadcast data at the top of the picture (possibly just about off-screen) during 'The Computer Programme' or one of its follow-ups, that a BBC Micro could decipher with some kind of dongle.