Bookmarks: Some stuff to read on the internet

Martin at Currybetdotnet explores the forgotten history of copy protection on vinyl records:

I dimly recalled that there was a form of copy-restriction placed on some vinyl albums. A high-pitched frequency was pressed into the album, which was inaudible to the human ear during playback, but which would destabilise the process of recording the album to cassette tape.

The reason I remember it more than anything was that a family friend had built some sort of decoder to eliminate the frequency, and was hoping, should it become widely adopted, to become rich on the back of selling little gizmos that would strip this primitive analogue rights management from recordings.