Teletext & Minitel

Ceefax, 1974. A network with no address bar: you reached a service by knowing its number.

P100 CEEFAX 100 Sat 2 Aug 21:47

IN THIS MAGAZINENOT IN IT

PAGEPress three digits.

You waited, because the page was not fetched.

Every page in the magazine was broadcast in a continuous loop. Your set watched the signal go past and grabbed yours when it came round. Ask for a page near the end of the cycle and you waited longer. There was no request, so there was nothing to hurry.

That page will never arrive.

That page was not in the magazine, and teletext had no way to tell you so. A request was not a request, so there was no reply and no error. The set simply kept waiting for something that was never in the loop.

The 404 is a courtesy this system could not extend.

Why teletext pages have ragged edges

Type a word, then add a colour before another word. Watch what the colour change costs you.

Nine cells used. No colour changes yet.

Minitel shipped a colour standard to monochrome terminals

France put colour in the spec. Most homes had a grey screen, so designers composed for the grey. Flip the switch.

red 50% · green 70% · yellow 90% · blue 40%

Field marks: how to spot teletext

The header row is 32 columns, not 40. The first eight cells carry control codes that are never displayed, and the last eight are the clock.
Ragged right edges everywhere. Every colour change occupies a real character cell, so text after a colour code starts one space later than you typed it.
Double height eats the row below it. A double-height line does not scale, it consumes the next row entirely.
Graphics are made of six blocks per cell, so every picture is built from nothing but colour and absence.
Exactly eight colours, full-intensity RGB and nothing between: black, red, green, yellow, blue, magenta, cyan, white.

What it cost

Ceefax ran for 38 years and stopped in October 2012. Minitel, which France gave away to get people online a decade before the web, was switched off in 2012 as well.

Both were slow, and both were free at the point of use, carried by infrastructure that was already there. Neither had an account, a login, a recommendation, or a way to know who was reading.

The problem it solved: information could be broadcast to everyone at once, with no request, no record and no reader to identify.

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Source. Cell geometry and decoder behaviour are taken from the captured edit.tf source (GPLv3, read only, not copied) and Minitel geometry from miedit. Type is Bedstead by Ben Harris, released into the public domain, derived from the Mullard SAA5050 character generator. The pages here are composed in the period dialect rather than rehosted: there is no freely licensed source of real Ceefax or Minitel page content, and broadcast pages remain third-party editorial copyright. This is a recreation, not an emulation.