Octopus Systems

Teletext+ Support

 
 

Teletext+ Support

Updated 1 July 2003

This is the support area for Teletext+ users. If you haven't already got Teletext+ then see the main Teletext+ page too.

Teletext+ is now fully compatible with the IYONIX pc.

Existing users can upgrade to Teletext+ v7.25 by sending a £15 cheque payable to Octopus Systems together with their master disc. Alternatively you may send a cheque and supply your serial number and Email address for an update by Email. Please add £5 (ie £20 total) if your would like a wire-bound 5th edition manual too.

Note that most Teletext cards, including those from Computer Concepts, do not have a podule ROM, so there is no need to update the card. Similarly, external teletext adapters from Ground Control, Solidisk and Morley will not need any updates other than the new Teletext+ software.

Teletext+ v7.25 Software

Features added recently include:

  • Now handles pages transmitted with incorrect checksums. Note that ITV no longer transmit correct CRCs, so this update is important for data logging from ITV (see below)
  • Grabs share price data from Channel 4 with their new transmission system
  • Alarms now work for programmes starting after midnight
  • Alarm window shows channel for TV and Radio programmes
  • Alarms can be set if keywords appear in programme description (not just title line)
  • TeleButler (TV output) display now shows the channel for TV and Radio programmes
  • Improved TeleButler display on televisions (less flicker)
  • Several script improvements
  • Fully compatible with RISC OS 4 and RISC OS 5

Problems with ITV Teletext

We have been in contact with Teletext Ltd to discuss the problems with Teletext broadcasts on ITV. They have just upgraded their Teletext insertion systems and have experienced a number of problems with their new software.

Initially the new system was sending pages with incorrect sub-page numbers, so a page with a single sub-page was being sent with sub-page number 1 instead of 0, and some other pages were sent with missing sub-pages (eg sub-pages 1, 2, 3, 29 and 30). This problem has been fixed in their latest firmware and the London transmitter is being upgaded today (2nd June). Other transmitters across the country should be upgraded soon.

This problem will cause Teletext+ to stick when it encounters a single sub-page with a sub-page number of 1. This implies that there should be more pages so Teletext+ will wait without moving on to the next page. Teletext+ will timeout if it doesn't receive a page within a set time, but in this case it will still receive the page and it won't timeout.

As a temporary solution you can remove any pages from your cache and scores file that suffer from this problem (ie any pages with a single sub-page numbered sub-page 1 that Teletext+ sticks on). Otherwise you will have to wait until Teletext Ltd upgrade your transmitter.

A more serious problem is the lack of CRCs checksums on their new system:

Corrupt Pages on ITV Teletext

Every Teletext page should be transmitted with a CRC (Cyclic Redundancy Check) checksum which enables the Teletext decoder to determine whether the page was received correctly.

The new hardware that Teletext Ltd have installed does not broadcast a CRC check at all as the manufacturers did not regard it as important. This violates the Teletext specification and is likely to cause problems especially for anybody who wishes to log data from ITV. It is unknown whether this is likely to be resolved, but if you would like to make your feelings known you can contact them on:

Broadcast Support Teletext Limited
101 Farm Lane
London SW6 1QJ

Fax: 0171 386 5618

When Teletext+ receives a page with an invalid CRC checksum it flashes an asterisk in the page header to indicate a fault, even though the page may be correct. ITV Teletext are sending pages with a CRC of 2020 for every page. This is a violation of the Teletext specification and it makes it impossible to determine whether a page has been received correctly.

This shouldn't affect Teletext+ users too much unless you have script commands to log data from an ITV page. In this case Teletext+ will wait until the page is received with a good CRC before moving on to the next page.

Teletext Ltd say they are investigating the problem and hope to resolve it soon. Meanwhile, we have produced a new version of Teletext+ (v7.09) which ignores the CRC if it is 2020. Just install the new version and the problem should be solved. For more technical details, read on:

More About CRCs

This section explains more about CRCs for users who want the full technical details - you don't need to read it to use v7.09. Some users have suggested that Teletext+ shouldn't stick on a page when the CRC is incorrect. In fact it will display and cache pages with a bad CRC just like pages with a good CRC, with the proviso that it will never overwrite an old cached page that has a good CRC with a newly received page that has a bad CRC (ie if you return to a page that has previously been received it will always show a good entry in preference to a newer version with a bad CRC). Once all of the sub-pages are received it will move onto the next page that it wants to cache. However, if a script command is used to log data from a page then Teletext+ will wait until a good copy of the page has been received.

If you are logging data from ITV then Teletext+ must be fooled into thinking that the pages have good CRCs when in fact they don't. This is achieved in v7.09 by telling it to ignore particular CRC values and treat the page as good when they are encountered. The CRC values to ignore are set in the Teletext+ !Run file:

     Set TTX$ignoreCRC 2020 8080 

This line makes Teletext+ ignore the CRC if it is 2020 or 8080 (hexadecimal).

A CRC error is indicated in the status window with a "BAD CRC" message when the page is received and the CRC also appears here. The cache list also shows bad CRCs by marking the page with an asterisk.

If another channel is posing a similar problem and showing BAD CRC on every page then you can identify the CRC value that is being sent and enter the same value in the TTX$ignore line.

Alternatively, if you have very poor reception and receive a lot of CRC errors you can make Teletext+ ignore the CRC check completely by changing the line in the !Run file to:

     Set TTX$ignoreCRC *

This may also be useful in countries where CRCs are not transmitted.

TeleButler Home Information System

It is now possible to connect your Acorn computer to all of the TV sets in your house to provide a useful home information system.

All incoming and outgoing telephone calls can be displayed on every TV set in your home, so when the phone rings you can switch to channel 9 and see who is trying to call you.

This is possible using a Computer Concepts tuner/teletext card which has an RGB/composite video output in addition to the normal Teletext functions. Our Caller Display and Teletext+ software work together with this card to make it display useful information which can be connected to your TV sets.

The display is quite separate to the computer's normal display, and the computer can still be used normally while it is generating the extra TV display. The TV display can be used to show all sorts of useful information and there are even system calls to allow your own programs put useful information on it.

Caller Display and Teletext+ update this display automatically, so if the telephone rings or Teletext+ beeps to warn of a television programme starting the details are immediately displayed on a spare television channel.

Display which can appear on channel 9 of every TV in your home

See our new TeleButler Home Information System page for more details.

Ceefax Regional Pages

Ceefax has just started broadcasting regional pages in most areas, with local news (page 160), weather (page 402) and travel (437). The TV pages (603 etc) also show the local ITV region. See Ceefax page 300 for a full regional index.

Irlam Risc TV Card

The Risc TV card offers a television display on your desktop as well as Teletext. It doesn't slow the computer down when displaying television (since the television image is overlayed on the video output which is routed through the card) and the window can be re-sized or made full screen. The TV sound is played through the computer's sound system and it is also available on a separate headphone jack. It has a composite video and S-video input for connecting video recorders, camcorders or digital cameras.

The system can grab still frames and save them as sprites and moving video is promised as a future upgrade. The optional Teletext module is needed to receive Teletext which works well with Teletext+.

If you already have Teletext+ and wish to upgrade your hardware we can supply the Risc TV card with the Teletext module for £339 (you can even trade-in your old teletext cards or adapters). We can also supply the Risc TV card, Teletext module and Teletext+ software for £369. Prices include VAT and carriage.

Hints for Risc TV Users

Steve Lee passed on this useful tip for Risc TV users:

If you have a video recorder connected to the composite video you can set the RiscTV to display the composite video input (channel 0) and then change the channel you are watching on the video machine (ie using the tuner in the video recorder). This allows Teletext+ to use the Risc TV tuner so it can happily hop between the channels without affecting your viewing. Obviously you need a video recorder to do this, but it is a very useful tip.

Hints and Tips

Multi-Line URLs on teletext Pages

Teletext pages often contain URLs (Universal Resource Locators) which you can click to open the relevant page (assuming you are connected to the Internet at the time). This works for Email addresses, web pages, ftp sites and some other Internet services. Similarly clicking on a telephone number will dial the number. However, some web page addresses are quite long and can extend over two lines on the Teletext page. In such cases Teletext+ only looks at the single line so it will not open the correct address. A simple solution is to save the Teletext page as text into Zap. It is then possible to join the two line by deleting the intervening space and Return character and then open the web page by Alt double clicking over the URL.

It has been suggested that Teletext+ should automatically detect such cases and append the next line if it looks like part of the URL. I don't think it is possible to reliably decide whether the next line is part of the URL so I am reluctant to do this as it may cause existing single-line URLs to fail should there be text on the subsequent line. Any suggestions would be welcome.

Searching Sub-titles for Keywords

You can search sub-title pages just like any other page, but if a match is found it will generate a beep rather than appearing in the keywords window. You can use this to search football sub-titles for the word "goal" or "scored". You can also use it to make the computer beep when a particular subject arises in a television programme. For example, you might hate Top of the Pops, but want to see one particular artist, or you might be interested in a single item that you know will appear on Watchdog or Tomorrow's World. For example:

     #define subtitles
     1888
     2888
     3888
     4888
     5888

     #search subtitles
     acorn
     goal

Teletext+ v7.08 uses three descending beeps to indicate that a keyword match appeared on a sub-title page. Earlier versions use a single, long, low beep.

When using this facility you must select the sub-title page on the required channel and Teletext+ will not grab any other pages while it is grabbing sub-titles.

TV Programme Listings

If you press REVEAL when looking at a TV listings page you'll see the date and an extra time appear on the page. This is used for video programming via Teletext but it can be useful to find when the last programme ends without going to the next sub-page.

Changes to Page Numbers

Many page numbers have been changed on Ceefax and ITV Teletext, and you may find that the page list facility no longer takes you to the right page. Furthermore, the keyword searching system will not be much use if it is searching the wrong pages for keywords. Since pages are normally searched by group name it is a simple matter to update the #define section of your script file using the new page numbers.

We have produced a new script file (21 Jan 97) which can be downloaded and merged with your existing script file. If you have entered your own keywords you should just replace the #define sections in your file with the one from this new script file. If you are using the default script file you can replace it with the new one.

Alternatively you can edit the script manually: Shift-Click on the Teletext+ icon (on the icon bar) and then double-click on the Script file. Search for the Radio programme listings (lines starting with 264) and change the numbers to start with 164.

For example, the radio 4 listings were on page 2644 (ie page 644 on BBC2), but they are now on page 1644 (page 644 on BBC1), so you should change the line:

     2644,Radio 4 Today

to:

     1644,Radio 4 Today

When you have changed all of the radio lines in your script file, press f3 and then RETURN to save the file.

Telephone Number Dialling

Many Teletext pages advertise telephone numbers and Teletext+ can dial these numbers automatically (via DTMF tones played through the computer's loudspeaker) when you click on them.

Teletext+ Keystrip

We now have a new Teletext+ keystrip with all of the mouse and key short-cuts listed. Our thanks to Roger King for providing the initial design.

You can download the keystrip from here and drag it to Spark or Sparkplug to decode it and extract the Draw file.

Teletext on the Web

Teletext Ltd provide Teletext for ITV and Channel 4 and they now have their own web site: http://www.teletext.co.uk/

Weekend Operation

Separate modes for weekend operation are not supported yet, although it is possible to install two copies of Teletext+ in different directories and use different script and score files with each one. A simple BASIC program could even be written to run the appropriate version depending on the day.

BBC Engineering Info

The BBC Engineering department has some new contact details for reception enquiries. You can now Email them on enginfo@bbc.co.uk or access their Web site on http://www.bbc.co.uk/info/reception/.

The Web site is particularly useful as it contains details of aerial types, reception problems and NiCam availability. Their new telephone number is 0345 010313 but overseas callers should use +44 181 231 9191 and this line is manned 0900-1700 on weekdays.

Teletext Specifications

More details of the Teletext system are available in the MRG Systems Tutorial. This will be of particular interest to users writing their own software to grab Teletext pages.

For more details please email us at (2)No such file or directory: exec failed (mailaddr.cgi) or see our contacts page for our phone number and postal address.

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