Introduction to the TELSTAR Viewdata system

From GlassTTY
Revision as of 10:35, 22 May 2018 by Glasstty (talk) (=Using the Service)
Jump to: navigation, search

The TELSTAR Viewdata System is a modern application that provides a simple viewdata/videotext platform in the style of Prestel (

Using the Service

The aim of the software is to provide a Viewdata experience for anyone who is interested in how thinng 'used to be'. The modern service uses an internet connection rather than over the public switched telephone network (PSTN). The service currently runs out of Digital Ocean's data centre in London and can be accessed using a Telnet modem, such as the modem described by Daniel Jameson ( or a WiModem232 (

Terminal software needs to be able to handle the Viewdata/Prestel format, packages are available for the BBC Micro such as Commstar. Set the speed to 2400baud (both directions) and set the parity to None with 8 data bits and one stop bit.

TELSTAR is available at the following address.

   Port: 6502


Currently the system takes several news feeds from the BBC and Reuters and others, and financial information from Google sheets. In addition a small computing section has been included which includes a Telesoftware service (see below) as well as a single feed from the forums.

The content is a little weak at the moment, especially on the intermediate pages, however, with the development of the Teletext convertor complete, It will be possible to edit pages using a Teletext editor such as the one at, and import all or part of a page into TELSTAR, converting to Viewdata format in the process. Therefore, as the system expands, it is hoped that the content will become more refined.


Routing is loosly based on the Prestel system, where navigation can take place by following the menu system, additionally, direct access to a page can be gained by using the special combination shown below.

   *<page number>#
       e.g. *890#

'Routing Map' support has been added which means that when following the menu selections pages, data from different IPs can be displayed. This mimics the original Prestel Cross Referencing service and allows full interlinking of content.

There are a few differences between Prestel and Telstar. Under Prestel, page rendering could be interrupted with a keypress. This was very useful in navigating deep hierarchical trees. This does not work with Telstar at the moment due to some nuances with streaming data to a TCP socket whilst listening at the same time. This is less pf a problem with Telstar that Prestel as the Prestel database was far larger and the system was therefore far more hierarchal that Telstar and secondly, data rates of 2400 baud is the recommended receive speed for Telstar rather than 1200 baud that prestel used.

Prestel used to have a history of three pages allowing the special sequence *# to move back one step. Telstar has an unlimited history.


The protocol used for Telesoftware is documented in the article [TELSTAR Telesoftware Protocol]. Due to the limited number of documents relating to the subject, the protocol was created by reverse engineering other software. To date the system has worked as expected with clients such as Pace's Commstar software.

The provided TEST program is a tokenised BBC BASIC program aimed at providing a simple mechanism for users to test their respective client systems.

More software will be published as it becomes available.


Copyrights and Trade Marks

It is the aim of TELSTAR to respect all copyrights and trade maeks. Please let me know if you are affected by any software and content that is published on the system.

Development Aims

The system has seen incremental improvements over the last few weeks and is now a reasonably stable viewdata platform. Content is generated automatically with data being updated every 10 minutes. Whilst this is ideal from a content management perspective, it requires that graphical content is created automatically also. This has shown itself to be quite challenging. It is an aim, especially as content grows, to develop this aspect further.

Other development activities under investigation are;

  • Response Frames, for data submission, messaging etc.
  • Master Pages to replicate Information Providers (IPs) section menus.
  • Apple II Viewdata Client Software
  • Arduino based Telstar Adapter (Telnet Modem)

Technical Details

The TELSTAR system runs on a Digital Ocean cloud based server hosted at glasstty.oerg, port 6502. The software is written in Python 2.7 and runs on Debian Linux (Jessie) and is managed by systemd.

Currently only a single service is running, referred to as Monty, however, the service can accept many concurrent connections. The service also includes a Telnet negotiation process that sets compliant Telnet clients to character mode as apposed to line mode. This is included to better support Telnet modems and to allow simple connectivity tests to be made using a standard telnet client.


  • [1] Fedida, S. & Malik, R. (1979) The Viewdata Revolution Associated Business Press
  • [2] Martin, J. (1982) Viewdata and the Information Society Prentice Hall