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Teletext and hypertext

Before the web, we had Teletext.

Teletext

As a child growing up with a home computer, I was fascinated by Teletext. Unfortunately, we didn’t have a TV with a Teletext decoder, as those were pretty pricey. My only chance to enjoy real Teletext was when visiting relatives. However, I had a BBC Computer, which had a Teletext mode known as Mode 7.

BBC Micro

In Mode 7, you could put a control character at a particular point on the screen, and all character cells to the right of that cell would display block graphics in a particular color when filled with a character code 160 or higher. Each character cell was split into 6 pixels, for 64 possible combinations represented by characters 160 to 255. Something similar exists today in the form of the Unicode block-drawing characters.

The Mode 7 screen was 40×25, so your maximum graphical resolution was 78×75, with the left column of cells being used up switching on graphics mode. Even for the 1980s that was pretty awful, but it had the benefit that an entire screen of text was only 1000 bytes. On a system with just 32K of memory in total, where video RAM was taken out of total system RAM, that was a major benefit. Plus, it meant you could fit 100 pages on a floppy disk!

As well as the poor resolution, there were obviously limits on which colors could be next to other colors, and how complicated your shapes could be. But the biggest problem was that working out which character codes you needed to (say) draw a box on the screen was a major pain. So in 1984 I wrote a teletext graphics editor which would allow me to create my own Teletext pages, with an easier way to draw lines and shapes and select colors. It also eventually supported automatic generation of banner text, text written in pixels. (Which, because the pixels were so big, was huge.)

I shared the program with friends at school, where we had a lab of BBC Micros. I also sent a copy to Personal Computer World magazine (PCW), who (to my surprise) published it. (This was back in the days when computer magazines printed listings in BASIC which readers would type in for themselves, and also back in the days when PCW wasn’t all IBM PCs all the time.)

Encouraged by my unexpected success, I went on to develop my own network-aware Teletext information system for the school. Users could create as many pages as they wanted, stored in their network filespace. (An Amcom E-net system with a hard disk.) Each page could link to other pages by username and page number. You could select page links using cursor keys then hit a key to go to that page. It was basically a primitive multi-user hypertext system, like the web — but in 1985, 5 years before the first web browser. I had been inspired by reading about Ted Nelson’s IBM and Brown University hypertext project of the 1960s, so I don’t claim any genius level originality; hypertext was something that was going to happen, we were just waiting for networks to get good enough.

I didn’t stop with text and graphics, though. I extended the system to allow downloadable executable code, so you could use it to build a hypertextual menu of educational software which you could launch right from the menu screens.

For some reason, nobody else at school was as excited by the possibilities as I was. Eventually I got an Atari ST, went to university, and started building hypertext systems on Unix. The code for my network teletext system is long lost at this point. I don’t even have the floppy disks. I wish I had kept them, if for no other reason than to provide examples of prior art to fight patent trolls.

I finally got my own Teletext TV in 1990, and enjoyed it for a few years before emigrating to a country that had apparently never heard of anything that advanced.

For more examples of Teletext pages, see the Teletext museum. It’s now being rediscovered as an artistic medium.