[memsom]

No, I was there. I'm British and in my 50's. I lived through this. I'm not remembering something I was told or reading you a Wikipedia article, I actually used this technology regularly in the 80's and 90's before Digital TV/DVB killed it off.

Prestel was something else. It was a teletext style system, but teletext was on every TV in the UK after the BBC started broadcasting CEEFAX (their service) and ITV started providing TELETEXT (their service). Channel 4 also had a service, but I don't remember what it was called.

Teletext was using the same style of presentation (BBC Micro had mode 7, and this was Prestel/Teletext compatible.) But Teletext was one way - it was broadcasted as part of the TV signal and your TV would decode the data and display it. If you wanted a specific page, you entered the number and then the receiver waited for the broadcast to get to that page and it decoded it and displayed it. There was no uplink. It all happened as part of the transmission and all of the pages were transmitted serialy in order so you would feel like entering in 123 would load page 123 directly, but actually it was displayed the next time 123 was transmitted.

[memsom]

In fact - ITV had ORACLE till the early 90's, Channel 4 had 4-TEL and TELETEXT didn't replace ORACLE till about 93. I forgot about ORACLE....