Octopus Systems

Teletext+ Technical Details


The fully RISC OS compliant Teletext+ software displays teletext pages in a window and happily multi-tasks alongside other programs. The user can choose pages either by entering a 3 digit page number on the keyboard, by using the on-screen keypad, by using the on-screen menu listing of page names or by clicking on a page number on the teletext page. For example, the News index usually lists 20 news stories, each with a description and a page number, and each story can be quickly accessed by simply clicking on the relevant page number.

A screenshot (90k) is available showing most of the important features.

Page Cacheing for Fast Access

The major problem with traditional teletext systems is the speed of accessing teletext data on a television set, or using a typical computer system can be quite tedious. After entering a page number it can often take 25 seconds before the page is available, simply because the teletext provider transmits each page in turn.

The Octopus Systems Teletext+ software avoids this problem by storing pages in a cache, ready for future use. The user can specify the size of the cache, but anything from 100K to 600K is reasonable.

Pages are automatically stored in the cache as they are received. A list of wanted pages can be stored on disc and the software will step through this list, grabbing the wanted pages. It does this transparently, in the background, without affecting the normal use of the teletext system. If the user selects a page manually then that page will be retrieved from the cache if possible, otherwise the system will grab the page and display it.

Sub-Page Cacheing

Some pages, such as television programme listings continue over several sub-pages. On a traditional teletext system it can be quite tedious waiting for the right sub-page to appear and remembering to press the HOLD button when it is displayed to stop it changing.

Teletext+ stores all of the sub-pages for each page as they are received and allows you to step forwards and backwards through the sub-pages. Cinema pages, share price listings and gig guides with 10 or 20 sub-pages can now be used quickly without any tedious waiting. Simply choose the page and use cursor left and right until you reach the sub-page you want.

Predictive Cacheing

The system logs every page number you request, and keeps a score for each page. If you look at a page quite frequently the score will grow quite large and the system will give that page a high priority, grabbing it as soon as it can. If you stop reading a particular page, the score will slowly decay and eventually the system will stop grabbing it automatically. The scores are stored on disc automatically when you quit (or shutdown).

When grabbing pages for the cache the software automatically changes channel, so it can grab pages on all of the channels you use.

In practice the system can grab about 6 teletext pages per minute. Letting the system 'warm-up' for 10 or 20 minutes means the most of the pages you read will be ready for immediate access. After an hour you will hardly ever need to wait for a page.

Saving Pages

Pages can be saved to disc as videotext (teletext pages), sprites, plain text or Impression DDF files. Teletext pages can be re-loaded into Teletext+ while sprites and text files can be loaded into other applications.

There is also a menu option (and a script command) to save all of the sub-pages within a page as a single text file. This is especially useful for saving pages containing large lists such as index pages, share prices, events guides and feature articles etc.

Keyword Searching

Keyword searching automatically searches for keywords as pages are received. Different pages and groups of pages may be searched for different keywords. It is quite easy to set up separate page groups for TV, Radio, News, Weather, Shares, Cinema etc and then search any combination of these groups for specific words or phrases. You could simply put all of the pages into one large group, but this is not always ideal as it can produce unwanted finds. For example, you may want to search the music pages for the pop group Thunder, but you don't want to be told when the weather page says there is thunder in Scotland (or vice versa!).

Page numbers are all 4 digits, the first digit being the channel number. Changing the keyword file is quite easy, and you can soon build up a large list of keywords to search for things like: TV programmes; radio programmes; actors and producers; music; local cinema and theatre; film news; share prices; weather warnings; pollen counts; local news. Once the keywords have been set up you will find the system constantly telling you about interesting news stories, events or television programmes that you would otherwise have missed. Some sample keyword script files are provided to get you started.

When a keyword is found in a teletext page it is displayed in a text window beside the main teletext window. Each entry shows the page title (as defined in the script file), the page number (including sub-page number), the keyword itself, and the line in which the keyword occurred. Clicking on one of these lines causes the teletext page to be displayed and the line containing the found keyword is flashed for a couple of seconds to help you find the reference.

Automatic Data Logging

As well as searching for specific keywords in pages, it is possible to log values on disc. When a keyword is found that line, or just the next value, can be appended to a text or CSV file. Their is also an option to include the date, and to suppress multiple entries, so if you run twice in one day it won't record the information twice. This is ideal for recording daily weather information or share prices, and the resulting files can easily be loaded into a spreadsheet. Commands can also be placed in the script file to save pages (with multiple sub-page), lines or values to a file and the filename can be generated from the current date to make it easy to log data daily.

Setting the Computer Clock

Teletext+ can set the computer's clock from the Television Service Data Packet (TSDP) which is broadcast along with the teletext pages. It can also be configured to check the system clock against the teletext time whenever it is run and warn if it is inaccurate, or if summer time has started or finished.

Internet Links

Some teletext pages have Email or WWW addresses and Teletext+ will pass these on to the ANT Internet software when they are clicked.

Saving Share Prices

Teletext+ can now save share prices in a format suitable for the Apricote Shares4 or Shares5 program. You don't need to transfer the shares file every day as Teletext+ will append the share prices to the data file on a daily basis and the data can then be incorporated into the portfolio database when needed.

An Example Script

As an example of the power of the script language:

   #define Television  
   1601 BBC1 Today
   1602 BBC2 Today
   3113 ITV Today
   4414 Channel 4 Today
   2631 BBC1 Tomorrow
   2632 BBC2 Tomorrow

This defines a group of pages with the name "Television". This means that subsequent searches can simply refer to this group name rather than the full list of pages. If the page numbers change you only need to change it once in the group definition. It also allocates names to the pages so that matching keywords can be listed in context with the page name.

   #search Television      ; Search the television group
   Star Trek               ; Display line in keywords window
   Scuba diving            ;  if these keywords are encountered in
   Ipswich                 ;   any of the television pages

This makes this system search the television pages for the phrases "Star Trek", "Scuba diving" and "Ipswich&. The comparisons are case insensitive and strip out punctuation, so &Scuba-diving" would also match. The matches are displayed in a separate window. See the screenshot for an example.

   #savealltext "TV#p" Television ; Save all television pages to disc

This would save all of the television programme listings (defined in the television group) with each page saved in a separate file and the filename is generated automatically using #p to insert the page number (#s can be used to insert the sub-page number, #d to insert the date and #t to insert the time). All of the sub-pages for BBC1 today would be saved in the file "TV1601" with each sub-page appearing one after another in the correct order.

   #after 3106 grass pollen
   +2 East Anglia

This command searches for the "grass pollen" listings on ITV page 106. Once it has found that phrase it then searches for East Anglia. This prevents the system from listing all of the other air quality statistics that appear on page 106 and just lists the pollen count. The +2 makes the next two lines appear in the keywords window so you can see the value without actually going to that teletext page.

   #fileoptions VNS
   #file "Acorn" 4532

This searches for the word AcornCmpt on the share price page and then appends the value it finds to the end of the CSV file "Acorn" along with today's date. After a few days the file would look like this:



Teletext+ can remind you when your favourite TV or radio programme is about to start. If it finds a keyword on a TV or radio programme page then it looks for a start time and sets an audible alarm (with a 5 minute warning) to remind you:

It can handle multiple alarms and alarms still work in the background so you can still use teletext while it is doing the keyword searching and data logging.

A simple command is included in the script file to enable this:

   #alarm "today"

This causes the system to set an audible alarm whenever a time is encountered in a keyword match on a page where the title contains the word "Today". For example, if the BBC1 listings include:

         1800 Star Trek: Picard meets the Borg

The system would set an alarm for 5:55pm (5 minute pre-alarm) causing this line to appear in a teletext alarm window (the Acorn Alarm application is not used as any unacknowledged alarms block subsequent alarms). Alarms are audible but use a different sound to the standard alarm application and they clear themselves automatically after an hour.

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