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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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26th May 2021, 12:46 pm | #21 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,189
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Re: Granada teletext model - can't find colour settings
I don't know this set, but I've come across many of the Philips TV ics and have the databooks.
CITAC = Computer Interface for Tuning And Control. It's an I2C bus device that contains much of a freuency synthesiser control system (needs an external prescaler and obviously the turner local oscillator) along with 'DACs' for things like brightness and contrast control. The CITAC has little to do with teletext. Extra page memories on that suggest the use of the SAA524x IC, which is indeed quite an advanced chip for the time. One feature of that, almost never used other than by me and the like, is that you can read and write the teletext page memory over the I2C bus. So you can (could, I guess) dowload teletext pages to a computer or use it as a simple text video display (I've done both). All quite useless now of course. |