Sir: The video recorder pictured in your "Where are they now?" piece about failed technologies (21 April) is not a Betamax machine, but the Philips/Magnavox video cassette technology, boasting clunky square cassettes, which predates Betamax by perhaps five years.
Students of the technological trash-can of history may also recall the Philips "Video 2000" technology, which boasted double-sided cassettes, longer playing times, and allegedly superior picture and sound. This system was available in the Betamax era, but was a catastrophic failure. A keen techno-junk shopper, I haven't seen a single Video 2000 machine since its disappearance in the early Eighties.
What happened to Elcaset, the quarter-inch "hi-fi" audio cassette format of the late Seventies?