When I wrote about Ceefax the other day, I hadn't realised one of our regular readers is capable of reeling off The Story Of Ceefax from memory.

So I was mildly surprised to find Carl, whose comments you might have spotted before, had written a comment as long as your arm beneath my pitiful Ceefaxy offering.

There's some cracking information in this so I've reprinted the majority of it here, since it deserves a slightly wider audience (the three people who read Dayorama as opposed to the one person who checks the comments).

Here we go then. I present The Life And Times Of Ceefax, by Carl...

"Ceefax (and indeed any other teletext services) pages are composed of a 40x24 screen. This translates to a row of text 40 characters across the screen, with 24 rows in total, plus an extra row for the Fastext (coloured) options on the very last line, making it 40x25 really.

"All tetetext services (and indeed Ceefax) are transmitted digitally over the analogue signals in the hidden areas of the picture. These are the parts of the picture, just beyond the top and bottom of the TV screen that you cannot see. On TVs made before the 1990s or so, it was possible for the viewer to adjust the picture, and it was here that the normally invisible parts of the picture could be made visible by adjusting the vertical hold, etc. Teletext services can be seen as little dancing lines at the top of the picture – very strange looking!

"There is no technical reason why teletext services cannot continue after digital switchover, and teletext services have been digital since their inception anyway! Indeed, some satellite and cable channels operate small services on digital platforms.

"However reliable it is, it’s often not a good idea to use teletext services to check your lottery numbers. The reason for this is that errors can sometimes occur, leading to the occasional character not being displayed at all, or perhaps even the wrong character! This does not happen with the newer interactive services, like BBCi, but they’re not quite as fun at times, or nearly as accessible or fast. Teletext services have a whole 7 megabits of capacity all to themselves!

"I know all of this off by heart – I didn’t look it up! How sad! Well, I have always wanted to be an ICT teacher. Why I do know these terribly nerdy facts about Ceefax? Well, I once edited pages like this, though these were viewed by around 1,000 or so people, not several million! This was in the heady days of the early 1990s – well, up until 1994 actually – where my secondary school run its own internal Ceefax-like service. We called this “Noticeboard”.

"In those days computers started up almost immediately, and after pressing a red function key, one was quickly presented with the main Noticeboard page. From here, you would enter a three-digit page number that would take you to any number of pages of information. In fact, we had hundreds! Pages included sports pages (the school was and still is recognised for its sports activities), a ‘home page’ for each form, fun facts, quizzes… all sorts.

"Lots of fun in those days, though it had to be shut down in mid-1994, when the BBC network was finally switched off and we moved to an all-PC network. I had the grand title of... wait for it... "Acting Deputy BBC Network Manager". Beat that!"