JVC announced VHS in 1976, and launched it round the world over the next two years. It blew away all the rival VCR systems.
For the first ten years all improvements, were compatible; new recordings still played on old machines.
For instance, when JVC developed a compact version of the cassette, for use in camcorders, an adaptor let the VHS-C cassette play in a full size deck.
The HQ system improved picture quality, but tape recorded on HQ decks also played on ordinary decks.
The introduction of Hi-Fi stereo sound was compatible, too, because all the tape contained two versions of the same sound, one in mono for playback on old decks and the other in hi-fi sereo for new machines.
But then, in 1987, the gold rule of backwards compatibility was broken.
JVC announced S-VHS, a Super system that would deliver far better picture quality than ever before. This would encourage tv manufacturers to improve set quality, and offer larger screens. So movie studios could sell and rent tapes that delivered widescreen images and rivalled a trip to the cinema.
That was the theory, anyway.
Unfortunately the only way to get such dramatically better quality onto the tape was to change the method of recording, so that higher frequencies were captured. This meant new magnetic tape coatings and new recorders to work with them.
Although new S-VHS decks could be made to play back old “standard” VHS tapes, the hundreds of millions of ordinary VHS recorders in homes round the world could not play the new S-recordings. So the movie studiios would have to make two versions of every movie, one standard and one Super.
Shops would have to stock both, too. They all said no. So there were virtually no S-VHS movie tapes to rent or buy. With nothing to play on them, there was no incentive for people to buy S-VHS decks. So there was no incentive for the movie studios to start releasing S-tapes. And they never did.