Oh, right, I played with this from the examples folder of BBC Basic. Really neat idea! Wish I could have played with Teletext more, but a combination of factors prevented me from doing so before everyone started turning it off.
Yes, it's only the example program from BBC BASIC but I thought it deserved its own listing. It can also be run on the web without needing to download anything (I wish itch.io allowed you to publish an app with both download and web implementations, but it doesn't seem to).