Techie resurrects teletext on a vintage BBC Master
You can get Ceefax via a Pi, but behold it in its most exotic of habitats
Got an old BBC computer in the loft, a spare Raspberry Pi gathering dust in a drawer, and a yearning to return to the days when Teletext was a neat thing?
Andrew Hutchings – aka "LinuxJedi" – posted a blog last week to warm the heart of many a retro enthusiast keen to revisit Teletext in its natural habitat: the Mode 7 display on a BBC computer.
Resurrecting Teletext has long been possible, and bringing the service to life on a Raspberry Pi hooked up to a modern television is relatively straightforward. If you want to experience life from the days when having a Teletext-capable television was impossibly glamorous but don't fancy the tinkering needed to make it happen, there's also a site for that.
But where, frankly, is the blood, sweat, and tears fun in that? And so, we come back to Hutchings and a recreation of Teletext on the screen of a BBC Micro – or, in this case, a BBC Master.
Hutchings followed the well-worn path of getting Teletext working on a Pi via the 3.5mm audio/video socket – now deleted from more recent incarnations of the hardware – but set about taking the next step: broadcasting the signal and having it picked up by a BBC computer.
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Hutchings' Pi, an old Model 3A+ with a fried GPIO due to an earlier experiment, pumped out a composite signal. However, an analog broadcast on a specific UHF frequency was needed. While an RF modulator to do the deed is (relatively) readily available, getting the information into Acorn's finest requires more exotic hardware.
The BBC Micro and Master already have the hardware to render the display, but something extra is required to pipe in the data. Hutchings picked up an old Morley Electronics Teletext Adapter, flashed the necessary ROM, and after a bit of adjustment and coordination with the supplier of the Morley unit, Teletext rode once more on a BBC computer, more than a decade after the BBC killed off Ceefax as part of the digital switchover.
We asked Hutchings why he went for the Morley device rather than Acorn's wedge. He gave us three reasons: "It was cheaper than the Acorn Wedge for me to acquire, it has a digital tuner, which I figured would be easier to work with than blindly twiddling dials, [and] powering from the BBC means I don't need as many 3 pin plug sockets when demoing."
Hutchings also told us that he'd now managed to acquire the Acorn device. "There is an advantage to them, which is that you can very easily modify them to use a composite input. But, I haven't tested mine yet, and they have tantalum capacitors inside which tend to short-circuit and explode with age, so I'd want to carefully refurbish it first."
We were delighted with the implementation of Teletext on a Pi and the appearance online of a Ceefax replica. However, Hutchings' work takes that experience to the next level, and, as such, we salute him.
"It is thanks to the BBC Micro that I learnt how computers work at a low level and can do what I do today." ®