alt Hacker Newslike the ones in Holland in the 90s? I don't remember if i noticed it in other countries at that time, but for sure there was like whole text areas on TV channels you could go to, and i think someone at the time told me there was interactive chat through the TV too but they may have been yanking my teenage chain.
There actually were ones that did interactive chat, but that required a modem too.
For teletext it would display 40x25 text with eight colours (the colour control codes took up a character space) and simple block graphics, which was stored in the first 25 lines or so above the top of the screen.
In the UK, the BBC ran Ceefax and ITV ran Teletext, which you could access with a button on your TV remote. These days it's actually possible to recover them from VHS recordings with really careful analysis (the bandwidth wasn't really there for it to work with a naive data slicer). During the day BBC2 ran "Pages from Ceefax" with some library music behind, when it didn't have Test Card F up (making Carole Hersee the most broadcast face on British TV, probably even to this day).