A look at the CBM BTX Decoder


BTX is an abreviation for the german word "Bildschirmtext". It was something like the french MiniTel, operated by the famous "Deutsche Bundespost". Like most other things operated by the "Deutsche Bundespost" (DBP), it did not work very well and was absolutely overpriced. As a result, the system did never fullfil the expectations, and even in the best days there were only some 100.000 users.

The DBP expected a user to buy an expensive BTX device and to pay monthly fees for beeing allowed to participate in BTX. The result of this was a very limited user count and a bad image, since there was a high percentage of "redlight" services.

To help market the BTX service, the DBP tried to convince computer manufacturers to sell special "BTX decoders" (an adapter card plus a BTX software) because these adapter cards could be sold cheaper than the standalone devices originally developed. One of the result was the Commodore BTX decoder for the C64, which was the best selling home computer in these days.

The result was the Commodore BTX Decoder. It had the same case as the Commdore REU with three DIN connectors on the rear side. One was connected over a sealed device (owned by the DBP) to the phone line. The other sockets were use to connect an additional(!) monitor or tv set. To utilize all functions of the module the user was required to connect this additional monitor or tv set. Top

One of the largest German manufacturers of telco equipment is Siemens. And in fact, the Commodore BTX Decoder was manufactured by Siemens and just labeled as a Commodore product. Commodore did this with several other products, namely printers, which were often manufactured by Epson or other printer companies.

Top The post horn on the left side of the label was the logo of the "Deutsche Bundespost". The numbers on top of the post horn were the license numbers of the device. In the old monopoly days, any device that was sold to connect to the phone line needed such a license number. The device had to pass very expensive and bureaucratic tests, which made it up to ten times more expensive than devices without the license number. Often, advanced features were only available with illegal devices. For this reason most mailboxes were using modems without a DBP license - and they often got busted because of this.

Unfortunately, I did not open the device when I made these photos a few years ago. So you have to live without a look into the decoder - at least until I find the time to do some additional snapshots.


Richard Atkinson Richard.Atkinson@cl.cam.ac.uk has made nice photos from both versions of the BTX decoder (yes, there were two versions, and I do have both of them, but I forgot that when I wrote the text above - I'm an old man, please bear with me). Have a look at his pictures.


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