Teletext on Amiga – the real world’s first!
In the aftermath of my Teletext experiments on Amiga – which I totally believed to be a world’s first breakthrough – blog reader Martin contacted me to tell me about his own Teletext experiments back in 1992, with a working solution in 1994, making his setup probably the real world’s first Teletext output directly from the Amiga!
Also check out Martin’s Teletext applications at teletext-manager.de!
It gets better: His Teletext work was even used in a real, actual broadcasting setup for a local cable TV provider in 1995! The technical details are interesting as well:
(I’m paraphrasing the key points myself here, kindly provided by Martin himself.)
- Amiga 500 with an added ECS Denise chip
- Custom screen mode screen mode based on Euro36 to reach the vertical blanking interval; border turned off
- Horizontally, the 360 Teletext bits are displayed in Amiga hi-res pixels
- Every 45th pixel, a duplicate pixel is inserted, stretching 720 hi-res pixels to 736 pixels
- That’s about the same approach I found to be best working in my own experiments – fascinating!
- Separate tools for bitmap generation and Teletext signal insertion, distributed on two Amigas connected via ParNet (ad-hoc network using the parallel port)
- One Amiga to produce Teletext pages as encoded bitmaps into a shared folder
- Another Amiga to read and display these bitmap patterns, while inserting a timestamp for the header rows in real time – fast enough on a 7 MHz Amiga 500!
- Coded and compiled in GFA Basic
- Additional tools: editor, decoder, renderer
- Teletext specs 8R4 and 8R5 obtained by snail mail from the German Institut für Rundfunktechnik, then responsible for standards and research on broadcasting technology
- Broadcast-tested at a local cable network, providing channel frequencies for TV, UKW and digital radio via Teletext, along with the operator’s imprint and some advertisements
Developing all this from a spec on paper, having no way to quickly look up some nasty encoding details on the internet, and probably only cumbersome methods (if any) to compare your actual Teletext signal with a known-good signal of the same content — I am in awe for this accomplishment!
Martin took my Worms shenanigans as an inspiration to dig out his original tools, acquire “new” CRT TV sets and get everything working again. Enjoy these screenshots of groundbreaking Amiga Teletext awesomeness in action!