Introduction to the TELSTAR Viewdata system
The TELSTAR videotex system, developed in 2018, is a modern application that provides a simple viewdata/videotext platform similar to those that were prevelant during the 1980s such as Prestel (https://en.wikipedia.org/wiki/Prestel).
The aim of the system is to provide a Viewdata experience for anyone who is interested in how things 'used to be'. Services in the past typically provided access via the public switched telephone network (PSTN) connection, however, Telstar makes use of a simple internet connection. Three Telstar servers currently operate from Digital Ocean's data centre in London and can be accessed using either a Telnet modem in conjunction with a home computer or from a PC/Mobile device using Richard T Russell's BBC Basic for SDL 2.0 example (see below).
For a full up to date list of content available through Telstar, please se the TELSTAR Directory.
- 1 Connecting and Using the Service
- 2 Connecting from a Modern PC or Mobile Device
- 3 Content
- 4 Routing
- 5 Telesoftware
- 6 Copyrights and Trade Marks
- 7 Gateway Facilities
- 8 Colossal Cave Adventure
- 9 Response Frames
- 10 Technical Details
- 11 Acknoledgements
- 12 References
Connecting and Using the Service
The service can be accessed using a vintage computer such as the BBC Microcomputer, Torch or Spectrum using an internet modem, such as the one described by Daniel Jameson (http://www.amibay.com/showthread.php?99878-WiFi-retro-Modem-for-under-a-tenner) or a WiModem232 (https://www.cbmstuff.com/proddetail.php?prod=WiModem232OLED).
To access the system from a PC/Mac/Linux/IOS/Android see #Connecting from a Modern PC or Mobile Device
A vintage home computer requires suitable vintage videotext software. Software designed for use with Prestel will work with Telstar, packages are available for the BBC Micro such as Commstar, other software packages produced in the 1980-90s exist for other systems. Ideally the speed should be set to 2400baud (both directions) and set the parity to None with 8 data bits and one stop bit.
Each internet modem will have its own method for connecting to an IP Address and Port combination, Telstar is listening on the following endpoints.
There are three instances of the TELSTAR service, these are named 'CURRER', ELLIS' and 'ACTON' respectively. The first two are identical and are available at the following addresses.
Url: glasstty.com Port: 6502
Url: glasstty.com Port: 6503
The third service is used to test new features and may be subject to short periods of interruption.
Url: glasstty.com Port: 6504
Please Note that these endpoints are not Telnet Servers nor Web Servers, they are simply TCP listeners.
Connecting from a Modern PC or Mobile Device
Richard T Russell has written BBC BASIC for SDL 2.0 (https://www.bbcbasic.co.uk/bbcsdl/) which is available for desktop (Windows, Linux, Mac OS-X, Raspberry Pi) and mobile devices (Android/IOS). This product includes a Telstar Client within the General section of the included examples.
The following images show the BBC Basic for SDL 2.0 Telstar client in use.
Currently the system takes several live feeds from the BBC, Reuters, Daily Mail, Express, Stardot.co.uk and others. This provides current and automatically updated news and financial information as well as information relating to arts, culture, sport etc. The data is typically refreshed every 10 minutes.
Some static content is provided, this includes index and routing frames as well as those encoded frames used for Telesoftware.
Some content is created by accessing external APIs. For example, the Weather service accesses the Yahoo Weather API.
For a full list of the content available please see the TELSTAR Directory. This is currently a 'work in progress' and will be expanded as the content is developed.
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#
Some special combinations allow for pages to be redisplayed of for navigation to a previous page as follows;
*00 Re-display current frame. *09 Re-diaplay current frame (included for compatibility). *# Navigate to the previous page.
'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 of an issue with Telstar than it would have been with Prestel, as the Prestel database was far larger and the system was therefore far more hierarchal than Telstar. It also helps if Telstar is accessed at the recommended baud rate of 2400 baud rather than 1200 baud that Prestel used.
Prestel used to have a three frame history allowing the special sequence *# to move back up to three frames. Telstar has an unlimited history. All other special sequences used by Prestel are supported.
The protocol used for Telesoftware is described in the document File:Prestel Telesoft Protocol Low Res.pdf.
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.
TELSTAR now features Gateway access to other viewdata systems. At the time of writing it is possible to 'gateway' to CCL4, over at fish.ccl4.org, and to the test version of TELSTAR for a sneak preview of any new features.
In addition, it is also possible to access some none viewdata systems, see #Colossal Cave Adventure below.
Colossal Cave Adventure
TELSTAR, via its #Gateway Facilities can now access the famous 360 point version of Colossal Cave Adventure.
Colossal Cave Adventure (also known as ADVENT, Colossal Cave, or Adventure) is a text adventure game, developed originally in 1976, by Will Crowther for the PDP-10 mainframe. The game was expanded upon in 1977, with help from Don Woods.
TELSTAR includes the facility to present forms to the user requesting input. The frames are referred to as response frames. The first use of this functionality was for the city/town/region search facility for the Yahoo weather service.
The TELSTAR system runs on a Digital Ocean cloud based server and runs on Linux, the services are managed by systemd.
TELSTAR is written in Python 3 and uses the Tornado library for networking. The service can accept many concurrent connections and includes a Telnet parser to better support Telnet modems and to allow simple connectivity tests to be made using a standard telnet client.
- Darren Storer http://www.g7lwt.com/
- Richard T Russell http://www.bbcbasic.co.uk/index.html
- Daniel Jameson https://stardot.org.uk/
- Rob O'Donnell https://viewdata.org.uk
- Dave E J Hitchins
- Dave Banks https://github.com/hoglet67/
- dukkie http://stardot.org.uk/forums/memberlist.php?mode=viewprofile&u=10052
-  Fedida, S. & Malik, R. (1979) The Viewdata Revolution Associated Business Press
-  Martin, J. (1982) Viewdata and the Information Society Prentice Hall
-  Money, S.A. (1979) Teletext and Viewdata Newnes
-  Stokes, A. (1980) Viewdata: a public information utility (2nd Ed.)