Telesoftware |
elesoftware was broadcast by both CEEFAX
and, for a time, ORACLE between 1982 and 1989. The data was
intended to be downloaded by a BBC Microcomputer fitted with a
Teletext Adaptor. There were at least two such - one made by Acorn
and another by Morley Electronics, and quite sophisticated software
techniques were employed to make downloading as quick and painless
as possible. As adapters became available for other computers, so
software for them was occasionally transmitted.
The broadcast software included computer programmes for the BBC Micro, notes and diagrams to accompany Schools broadcasts, and a series of text documents describing how to use the Teletext Adaptor, accompanied each week by a relevant demonstration programme.
Here are five of the very early test programmes, broadcast around June 1982, which were transmitted as plain ASCII listings, and which I copied down into an exercise book whilst waiting for delivery of my BBC Micro. They are in the form of text files which you can download and read. They can be run on an Acorn computer or one running BBC BASIC under emulation by saving the file to disc and typing *EXEC <filename> at the > prompt.
You can find BBC Emulators for other computers at www.emulation.net.
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his programme is typical of many that
appeared in the computing magazines of the time. It demonstrates
the Beeb's ability to do calculations and screen drawings rapidly,
making great use of the RND and trig functions, and long variable
names.
The programme draws twenty-five random polygons on the Beeb's Mode 1 (4-colour 320x256 pixel) screen.
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his is a much longer (127 lines) programme
that was featured in "The Computer Programme" BBC television show,
book and software cassette. Viewers were encouraged to type in the
listing and so make friends with their new technological purchase.
The programme simulates landing a lunar spacecraft by firing the retro rockets in bursts to slow it down. The listing is as transmitted, but I found I needed to add a routine to slow down execution before it would run properly on my Archimedes, and I've made a note of the changes at the end of the listing.
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his programme calculates the "Modified
Julian Date" for any date entered in the range 1 Jan 1900 - 31 Dec
1999. The MJD is a decimal form of the date which can be very
useful in calculating periods of time, and is also included in the
"hidden" packets of teletext transmissions.
Although the programme as presented here is not "y2k compliant", there is no error-checking of values typed in, and it's possible to calculate the MJD of 1 Jan 2000, for example by entering 100,1,1 or 99,13,1 or 99,12,32.
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hese programmes are two versions of the
same one with different data. There are various routines for
drawing lines, rectangles, circles and text according to the data
coded into BBC BASIC DATA statements. Note that CEEFAX and ORACLE
themselves were transmitting similar pages of teletext diagrams to
accompany Schools broadcasts at the time.
The programmes have been "crunched" prior to transmission - all the BASIC keywords have been replaced by their shortest abbreviations, and the variable names have been reduced to single letters, all of which makes the programmes less readable to the human eye. |
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Teletext Website Bookmarks Rob Hardy's UK Teletext Site UK Teletext Mailing List Digital Teletext 625: Andrew Wiseman's Television Room |
Compiled by Alan Pemberton
Sheffield, South Yorkshire, England
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