Level 2.5 Teletext part I

Level 2.5 Teletext is an extension to the original teletext standard where packets > 24 can be used to, amongst other things, define new colours maps and dynamically redefine character sets (thus giving access to high-resolution graphics).

Not many broadcasters use Level 2.5, but ZDF do in a limited capacity:

The standard Level 1.5 view.  But if your set supports it...

...a few seconds later you get the Level 2.5 version

Latest: Last two grabs incorrectly dated; Ceefax technical page

Well, I thought that the post-1991 Ceefax pages were going to be completely boring but there is a single test page in the carousel at page 595:

What does this all mean?

On deeper investigation, the recent BBC grab and the YTV ORACLE grab are from 1992, despite the 15 September being a Saturday in 1990.  Unbelievably, the headers are consistently reading the wrong date, both on the Ceefax and ORACLE grabs - the news items point to September 1992, so it's either the 5th, 12th, 19 or 26th September.  It's definitely a Saturday as the TV Guide confirms this.  My guess, from the news, is that it's the 5th.

I need to find older recordings to go at.  I seem to remember that Ceefax was full of music reviews, puzzles, telesoftware and quizzes, and was much more magazine-like in feel; I'd love to see it again.

ORACLE processing done, Ceefax started

The YTV ORACLE processing has now finished (50,000 VBI frames!) and can be found here: http://teletext76.no-ip.org/ytv-19900915

Adding more VBI frames seemed to become less effective over time - it might be that the deconvolver always interprets certain characters incorrectly, and these reinforce themselves over time.

I've started another grab processing: it's from the same tape, and is the horrible cyan Ceefax design from when BBC News (I think) took responsibility of it. I'll check this when teletext.mb21.co.uk comes back up.  You can see this here: http://teletext76.no-ip.org/bbc1-19900915