Brussels / 1 & 2 February 2025

schedule

Bildschirmtext - Reeenacting an ancient communication system using Javascript and Common Lisp


The German Bildschirmtext system was an early large-scale public access information service established in 1983. Using telephone connections, users would dial in to a central system which offered them with access to commercial and non-commercial offerings. Television sets were used as display devices, with a set top box or built-in decoder proving the terminal functionality. Communication was bi-directional with a low-speed back channel that allowed typing in text messages.

The introduction of Bildschirmtext overlapped with the home computing era, but for regulatory reasons, home computers could not easily be used as Bildschirmtext terminals. This, among other technical and non-technical reasons, caused the service to fail to reach its full potential. It remained in use as a carrier system for home banking and other high security applications until it was finally switched off in 2007.

As Bildschirmtext was a centralized system operated by the federal Deutsche Bundespost on mainframe systems, much of the content that was available has been lost. A couple of the original data files of the Chaos Computer Club have survived, however, and as the CCC became notorious in the context of Bildschirmtext, that content made for an entertaining exercise in re-engineering.

In the talk, I will present my journey as a recent Bildschirmtext enthusiast. I will describe how the service was organized, how content providers edited content and put it into the system and how users would access it. I will also dive into my implementation of a Bildschirmtext terminal emulator in Javascript and a central service system written in Common Lisp, providing the audience with an insight of the challenges, constraints and possibilities of the system.

Speakers

Photo of Hans Hübner Hans Hübner