"As far as I remember, the idea for teletext came out of a Graduate Trainee Study Group (a kind of 'think-tank', when we had time for that sort of thing). The idea was originally for subtitling for the hard-of- hearing. I remember it being said that it would only be viable if the cost per set could be less than about £5.00! At the time, that was about 1/16th of my monthly take-home salary. That was in about 1970, possibly 1971. I still have the file in my office, but unfortunately only the cover, which has been re-used. The contents have long since disappeared."Bob Walker of the BBC, from Teletext Then and Now
Confirmation that the initial brief of teletext was to provide subtitles.
Why were the pages so limited in size?Adrian Robson, from Teletext then and Now
One factor was almost certainly the cost of memory. In around 1975 it cost £50 for the amount of memory that held one page, i.e. 40 characters on 24 lines, or around 960 bytes.
960 bytes? That's not even a kilobyte!
The Alarm Clock page - 160 - was updated every minute providing the original intended use for the Time Coded Page function. At the preselected time the ALARM CLOCK graphic would be superimposed onto the picture in a similar way to a newsflash. (These days the TCP function is more commonly used to access a specific sub-page.)From An Evening With Ceefax, Teletext then and Now.
Maybe I need to look into this alarm clock function more. I've seen it before on the Paramount Text pages but I've never actually seen it in practice. I wonder if it is no longer available?