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Parabola · 5th Mar 2012, 1:25 pm

Hello again,

As this thread is still open, and the final development work mentioned in post #26 is now complete, I thought I would just add a final update to conclude the story.

Just to recap. The new firmware and PROM layout allows 3 pages of text per frame (PROM). So, for an 8 field (4 frame) 4 PROM PAL colour test card 12 pages of text are possible, and for a 2 field (single frame) 1 PROM monochrome test card 3 pages are possible. This means that for a unit configured with all 625 test cards the total text pages held can be a maximum of 18. If the unit is configured to include a 405 test card, and thus only two 625 test cards, the maximum available text pages drops to 15.

The total available pages are divided up into separate magazines. The 12 pages available when the colour test card is selected are in the 1xx (100,101,102 etc) range, with the remaining two mono test card selections having pages in the 2xx and 3xx ranges respectively. This is necessary to avoid confusion to the poor old teletext decoder when switching between test card selections. If this is not done, then the situation can arise that if you manage to switch between test cards (and thus text magazines) between fields within a frame, it is possible to end up with the top half of one page and the bottom half of another – most disconcerting! A well defined numbering system prevents this.

As it’s time to wrap this saga up, I really should publicly thank a few people (Oscar-esque speech coming!)

Firstly, to Richard Russell, whose own TCGEN was a huge inspiration for this project, and whose BB4Win made is possible for a numpty like me to be able to create software applications powerful enough to create and manipulate PROM data how I needed it.

Secondly, to Jeffrey Borinsky, for finally pushing me down the CPLD route, and away from CMOS/TTL – it was key to this design getting to the point it has. Also, for his patience dealing with my daft questions whilst trying to get to grips with VHDL, digital PAL coding, and the black art of DAC reconstruction filters.

Finally, to my beta testers and fellow TV hoarders, you know who you are, who have provided feedback, support and encouragement through the darker times when it all seemed to be too much effort.

Thank you, all

So, to finish up, a whole sequence of pictures (if I get them all uploaded) showing an all 625 configured unit doing it's stuff through a 26” 1979 Philips G11 with Teletext and Viewdata decoders, touch tuning and ultrasonic remote.

All moiré patterns and strange colour rendition (orange reds!) are down to the camera, sorry.

The first set of pictures show –

1) The set-up – IMOGen --> Modulator --> G11
2) 625 PAL Colour Test card, TCF
3) 625 Mono Test Card 1, TCC (625 version)
4) 625 Mono Test Card 2, TCD (not accurate for 625, but for input to an Aurora)

More to follow…..

5th Mar 2012, 1:25 pm	#32
Parabola Retired Dormant Member Join Date: Sep 2008 Location: London, UK. Posts: 117	Re: IMOGen Test Card & Teletext Generator Hello again, As this thread is still open, and the final development work mentioned in post #26 is now complete, I thought I would just add a final update to conclude the story. Just to recap. The new firmware and PROM layout allows 3 pages of text per frame (PROM). So, for an 8 field (4 frame) 4 PROM PAL colour test card 12 pages of text are possible, and for a 2 field (single frame) 1 PROM monochrome test card 3 pages are possible. This means that for a unit configured with all 625 test cards the total text pages held can be a maximum of 18. If the unit is configured to include a 405 test card, and thus only two 625 test cards, the maximum available text pages drops to 15. The total available pages are divided up into separate magazines. The 12 pages available when the colour test card is selected are in the 1xx (100,101,102 etc) range, with the remaining two mono test card selections having pages in the 2xx and 3xx ranges respectively. This is necessary to avoid confusion to the poor old teletext decoder when switching between test card selections. If this is not done, then the situation can arise that if you manage to switch between test cards (and thus text magazines) between fields within a frame, it is possible to end up with the top half of one page and the bottom half of another – most disconcerting! A well defined numbering system prevents this. As it’s time to wrap this saga up, I really should publicly thank a few people (Oscar-esque speech coming!) Firstly, to Richard Russell, whose own TCGEN was a huge inspiration for this project, and whose BB4Win made is possible for a numpty like me to be able to create software applications powerful enough to create and manipulate PROM data how I needed it. Secondly, to Jeffrey Borinsky, for finally pushing me down the CPLD route, and away from CMOS/TTL – it was key to this design getting to the point it has. Also, for his patience dealing with my daft questions whilst trying to get to grips with VHDL, digital PAL coding, and the black art of DAC reconstruction filters. Finally, to my beta testers and fellow TV hoarders, you know who you are, who have provided feedback, support and encouragement through the darker times when it all seemed to be too much effort. Thank you, all So, to finish up, a whole sequence of pictures (if I get them all uploaded) showing an all 625 configured unit doing it's stuff through a 26” 1979 Philips G11 with Teletext and Viewdata decoders, touch tuning and ultrasonic remote. All moiré patterns and strange colour rendition (orange reds!) are down to the camera, sorry. The first set of pictures show – 1) The set-up – IMOGen --> Modulator --> G11 2) 625 PAL Colour Test card, TCF 3) 625 Mono Test Card 1, TCC (625 version) 4) 625 Mono Test Card 2, TCD (not accurate for 625, but for input to an Aurora) More to follow….. Attached Thumbnails Last edited by Parabola; 5th Mar 2012 at 1:31 pm.