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When I first set up my "digital TV antenna", I remembered how annoyed I was at the lack of TV guide information attached to all those tens of megabits per seconds worth of data. Many channels have nothing, some have the current show's title, and if you're really lucky, some description about the current show. Nothing about what's next.

It just so happens that, in the 70s, the BBC transmitted not only digital text information alongside the TV signal, but even published software you could download. And, yes, that included some TV guide information.

I discovered "datacasting" about 15 years ago when there was a clearance sale of Microsoft SPOT watches, just before the radio service it was using to display "data" was discontinued (that is, if it were ever available in Montreal). At that time, I was starving for a digital watch of any kind, and only ridiculously bulky analog watches were available (apart from the few sport digital watches, which were even bulkier).

There was also the rare mystical Satellaview ROMs for the Super Famicom. Those time-limited games were downloaded over satellite into some flash memory storage, and only a few of those games were backed up before they were automatically deleted at the next transmission.

What I didn't know was that, in the late 70s, in the UK they were taking advantage of the amount of time between the TV frames to send some data in the television signal (the "Vertical Blanking Interval"). It isn't a lot of data, but it was enough to send multiple pages of text in a minute, using affordable technology available at that time. This was "Teletext", also called "Ceefax" by the BBC. Even if microchips at that time had almost no memory, the pages of text would be resent with the TV signal continuously, at a rate of about 7 kilobits per seconds.

Interestingly, TV tape recorders recorded all of that signal, not just what is visible on the television screen or is audible, so a few old recordings still have that teletext data. A few example of archives are available from Nigel Reed's Teletext site, the one from, and The Teletext Archive. If you want an interactive experience simulating a TV that supported teletext, you can try the Teletext Viewer.

In the 80s, the BBC channel also had a few Teletext pages dedicated to "Telesoftware", a few small educational BASIC programs that could be downloaded to a BBC Micro using a "Teletext adapter". Here's an example of Telesoftware from 1983 (use the page and subpage links to browse), though it should be noted that, due to the age of those tape recordings, the text got corrupted a bit.

Teletext remained in use until the late 2000s in Europe. So, what did we get in North America? We got Closed Captioning, copy-protection (CGMS-A and Macrovision) and age ratings (using the infamous V-chip). Embarrassing.

Published on July 3, 2023 at 14:40 EDT

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