Screen text (short BTX or BTX, in Switzerland Videotex ) was an interactive online service. He combined telephone and television screen to a means of communication.

BTX was introduced in Austria in June 1982, in the Federal Republic of Germany from 1 September 1983 nationwide. Today screen text has lost its meaning due to competition from the open internet, now the service in most countries is set.

Was in the general population and on-screen text is often confused with the television video text, which also helped that the service in Switzerland Videotex was called (without t end ).

  • 2.1.2 DBT -03 and other modems
  • 2.1.3 Unlike the Internet



BTX was presented in 1977 by the then Postmaster General Kurt Gscheidle at the IFA exhibition in Berlin. It was developed in Germany under the direction of Eric Thank you, the later a board member of T -Online. Thank you Eric was in 1975 became aware of by a specialist publication on Samuel Fedida and PRESTEL on the original British technology. In 1980, a field trial with about 2,000 participants in Dusseldorf with Neuss and Berlin. On March 18, 1983 in Bonn, the Government of the countries signed the treaty on screen text. The contract is set free to anyone interested to act in accordance with certain rules as a provider of on-screen text. The German Federal Post launched in 1983 an interactive on-line service, which initially required a sophisticated videotex device. In 1983 there was next to the videotex videotex control center in Ulm switching centers in Dusseldorf, Hamburg, Frankfurt, Munich and Stuttgart. The plan was to expand to 150 Btx exchanges. The expected user numbers were never achieved. So it should be around one million in 1986, actually there were only 60,000. The Million was only ten years later reached after BTX was coupled from 1995 with the new T - Online offer including email and Internet access. BTX 1993 became part of the newly created service Datex -J. On 31 December 2001, the original videotex service was officially shut down. A stripped-down version for online banking was operated until 10 May 2007.


In Austria there were Btx since June, 1982. MUPID house development, a special terminal for the use of videotex services, was developed by the former PTV itself and could be rented by the users. The videotex terminal cost was in March 1984 around 150 ATS and the monthly fee was 70 ATS. The service has been end of November 2001 set.


The service was called in Switzerland as videotex (without t end ). Having started from the former PTT in the 1980s, he was operated from 1995 by Swiss Online. 30 September 2000, Videotex was adjusted.

Other countries

In Denmark there was the name of Teledata, in Italy and in the Netherlands Videotel Viditel; the greatest success had the appropriate French Minitel system under the name.

Features screen text in Germany


The German videotex originally required special hardware that had to be purchased or rented at the post office. The transfer of the data was carried out over the telephone network with a modem ( DBT -03) or acoustic, the appearance on the TV, PC monitor, or on a special videotex device.

BTX used, as well as the French Minitel, originally the British PRESTEL standard, then the standard CEPT T / CD 6-1. Later on the backward-compatible KIT Standard ( Kernel for Intelligent communication terminals) changed, but who could never enforce properly. CEPT allowed the transfer of graphics pages with a resolution of 480 × 240 pixels, 32 out of 4096 colors simultaneously and DRCS ( Dynamically Redefinable Character Set) could be shown. This corresponded to the technical possibilities of the early 1980s. Many videotex pages of PRESTEL standards were similar to the teletext pages still in use today with a line graphic of colored ASCII characters. In Btx first ever whole pages at a speed of 1200 bit / s were transmitted. The page request by the user was performed with 75 bit / s The possible access speeds have been increased with the advances in modem technology also from the Federal Post Office.

The downloading of data and computer programs ( telesoftware ), especially shareware and program updates, using a software decoder and a PC was possible.

The pages have been addressed by a number of prefixed with an asterisk (*) and adjusted in this context referred to as a "hash" hash character ( # ) was (eg * 30000 #). By the end mark # the system could distinguish so at address number entries if the entry is complete or there are more digits and creates a larger (theoretically infinite ) number available space remained ( counterexample: Telephony with entering numbers without end marker ). Numeric entries without preceding asterisk were interpreted as commands, which led some to another page (eg " 23") or confirm a paid page view (to avoid accidental confirmation is always " 19"). The combination * # led back to the previous page.

DBT -03 and other modems

The DBT -03 modem allow a data transfer rate of 1200 bit / s for participants and 75 bit / s from the subscriber to the center (ITU- T V.23 standard). The access authentication took place over the twelve digit connection ID (which was hard-coded as a hardware ID in the ROM of a DBT -03) and a password, which the user could specify. Then the operation with other modems was later allowed ( after applying a so-called software identification ). Thus, it could be used (for example, Amaris ) BTX with any ordinary PC and a so-called software decoder. Also for the C64 and C128 there was a videotex hardware decoder for the expansion port and connection to the DBT -03.

As in the DBT -03 modem, the connection identifier was hard-coded, an opening was not right. The modems were sealed, an opening could be made only by destroying the seal. An original device had a yellow, after repair, it got a blue seal. The dial-in number was hard-wired to the phone number 190

Unlike the Internet

At the German videotex system, the part of providers were stored in the Urdatenbank on a central computer system from IBM in the BTX - control center Ulm and retrieved from there if the local screen text exchanges ( Vst ) this is not in their database or participants had computers available. The local node could use the page requests from 95 to 98 percent. The page file on the local node was subject to an aging process. Little requested pages were overwritten with frequently requested.

The pages of so-called " External computer " this were an exception. They did not exist statically in the database of BTX - control center, but were each dynamically generated by the computer of the provider and transmitted to the user via the BTX -Vst. The external computer were connected to the videotex Vstn in the global network via X.25 ( Datex -P). This possibility was only a few major vendors (eg source), but which is used as a precursor of online banking by many banks.

On the Internet, there is neither an unconditional central instance still exists a fundamental division into information providers and users. Instead, the computer all participants are on the Internet largely equally and can occur in both functions.

Costs and Offers

The cost to the user caused by the retrieval of a page; the provider has, for the classification largely free hand. He was next to the free on demand either a page- based compensation ( 0.01 DM to 9.99 DM) collect, or a time-dependent compensation ( DM 0.01 to DM 1.30 per minute). The costs were charged to the phone bill of the users.

BTX already offered numerous services that are available on the internet today. So BTX participants could discuss with each other online (chat), mutually send electronic messages in the form of videotex pages for the price of 30 cent per page and get the latest news (ticker, homepages ). Furthermore, there was the opportunity to make their offer dynamically via a so-called " external computer " for providers. It was established a connection via Datex -P to the computer of the provider on a "hand- side " of the normal page inventory of the respective videotex exchange. From then on, then took over the computer control of the page contents displayed on the terminal. This offer was mainly used by banks ( as a precursor of today's online banking system ), mail order companies and the travel industry (Lufthansa, Air Inter, German Federal Railways or German Railways). The BTX customers are able to interactively conduct their banking transactions or give online orders by mail order. Even federal agencies such as the Employment Service were accessible via Minitel.

The setting of offers in BTX was relatively expensive, so it was hardly used by private individuals. Providers were mainly large companies such as mail order and individual SMEs. Also at Btx an ever increasing number of providers in the Adult area was observed.

The Chaos Computer Club was also represented with an offer in BTX. The club took a number of technical weaknesses in BTX and tried to show the limits of the system, including through the reported national television Btx hack.

Nevertheless, remained Btx the great success denied, mainly due to the restrictive policy, high user fees: lay a solid binding contract with the Federal Postal (1983 DM 8.00 monthly fee and a connection fee of 55.00 DM). This allowed for the use of BTX only specific, authorized by the post office hardware that had to be purchased separately at high prices. Although CEPT decoder were like the C64 available for home computer then spread at an early stage, the Post refused the admission of these devices. In France, where the necessary hardware was provided by France Télécom, partly free, the local contrast, Minitel enjoyed great popularity.

The post - monopoly on these terminals, modems and phones did not come until the early 1990s. At the time, private mailbox networks such as FidoNet or MausNet that could offer some of the available via videotex services for private individuals far more favorable spread. In the area of electronic banking long time there was no alternative to BTX.

BTX 1993 became part of the newly created Datex -J service to separate the network infrastructure of the information service. Datex -J with BTX was redesigned in 1995 to T-Online.

The subsidiary T -Online International AG operated the system until May 2007, however, under the name "T-Online Classic" and with strong encryption, where one was ITSEC " E4/hoch " certified encryption library Transport / S in use. To ensure that the access to the "T- Online Classic Client" on the Internet world was possible under the URL " classicgate.t" on port 866. Alternatively, some banks also operate the CAT system (CEPT Access Tool ). A separate CAT - emulated server for the existing access at T-Online.