IN-DEPTH Exploring Prestel

Mike Bedford shines a spotlight on the online data service that predated the World Wide Web by more than a decade…

T hirty years ago the CERN European particle physics laboratory near Geneva in Switzerland released the first web browser. For the first time, the World Wide Web, which had been developed at CERN a couple of years earlier in 1989 by British scientist Tim Berners-Lee, was available to other research institutions and the general public. It’s no overstatement to say that the world has never been the same since.

How that milestone has influenced industry, commerce, popular culture and so much more is well-known. What is less well-appreciated is the technology that this momentous achievement helped bring to a close. That earlier technology – the UK’s Prestel system and similar Viewdata services in other countries – is our subject in this month’s feature.

This isn’t just a history lesson, though. We’ll show you something of the underlying technology using some exercises that you can try out yourself and, if you’ve ever doubted it, you’ll discover how much of a game changer the web really was compared to its predecessor.

CONNECTING WITH PRESTEL

“Although some home computer users accessed Prestel on their BBC Micro, ZX Spectrum or similar, most people used a Prestel adapter.”

Prestel uncovered

If you’re not old enough to have delved into Prestel back in the 80s, or if you were around at the time but, like so many people, never used Prestel, let’s take a look at what is was like. In fact, even if you’re a former user of the system, you might still like to take a look to remind you how different it was to today’s online world.

Although Prestel closed back in 1994, you can find an emulator at https:// vd-view.azurewebsites.net which enables you to access several Prestel-like services. Once you head over to that site you’ll be presented with a display screen on the left and a keypad on the right. You’ll probably prefer to use the keys on your keyboard, but these will be limited to the figures 0 to 9 plus * and #, as the on-screen keypad makes clear. For although some home computer users of the early 80s accessed Prestel on their BBC Micro, ZX Spectrum or similar, most people used a Prestel adapter.

This connected to a TV and the phone line, and which had just a numeric keypad as its user interface.

To start, you need to select your service and, at least initially, we suggest that you choose Telstar (slow) from the menu at the bottom of the keypad. Then click Connect. Unlike most of the other supported services, this restricts the speed to that which was achievable on Prestel and you’ll notice two things: First of all, you’ll be able to see pages bring written, character by character and line by line, and it takes several seconds for a page to appear. Second, despite the slow update, the screen resolution isn’t exactly high. Specifically, all pages are 24 lines of 40 characters plus a header line and, although graphics were supported, this was achieved using special so-called mosaic graphics characters, which split each character position into two blocks horizontally by three blocks vertically.