Happy 50th birthday, Compact Cassette: How it struck a chord for millions

A while ago a solicitor rang me about a case, and asked me if I could work with really archaic recording technology. Wondering if he had perhaps found some wax cylinders, I was surprised when he explained that these antiques were in fact compact audio cassettes - the common or garden analogue cassette! Of course, I said, we work with them all the time, as these are what the police use for recording interviews under PACE.
And it is the 50 year anniversary of the cassette:

http://www.theregister.co.uk/2013/08/30/50_years_of_the_compact_cassette/