archive.worldofdragon.org

Evening all! I've been tweeting about French Dragons (check out my daily Dragon tweets at @herebedragons3), and becoming increasingly intrigued. There seems to be two main types - the one with the daughterboard and second DIN output, and the one with a bunch of new circuitry on the PSU board, which you can see here - https://worldofdragon.org/index.php?tit ... CB_Top.jpg

Now, this PSU board only seems to be paired with this motherboard, the PN41503 - https://worldofdragon.org/index.php?tit ... ssue3).jpg - and here's my question. Has anyone ever seen one on a normal UK Dragon? I have more than a handful of machines here, and I've never seen one. Also, who are Parc Electronics Ltd (I note they're Welsh, but I can find little more), why did they build them - and why did they use French Thomson branded 6821 chips?

Also, there's the 1601 modulator on the PSU board - that, I think, is a SECAM modulator. I don't understand enough about video to know what you would need to modify on a Dragon to produce a SECAM input for that - was that all done on the PSU board, or would the motherboard need modification too?

Is it possible the PN41503 is unique to French machines and produce SECAM, or is it the same as PAL motherboard?

Answers on a postcard to ...

Cheers, Tony

Hi Tony!

I don't know if you've already found it but there was a discussion here on the SECAM boards a while back:

https://archive.worldofdragon.org/phpBB ... =9&t=10921

It looks like the boards need to be paired as the power connector seems to have a different layout. (i.e. resist the temptation to mix & match boards!)

Just to add to the intrigue I'm sure I've got a Thomson branded 6809 somewhere.

PARC electronics was liquidated in the 80s. There is a company in Wales called PARC Circuit Technology but could just be coincidence.

Great stuff,Stew!

I was thinking about the possibility that they standard board and the SECAM PSUs cannot be matched, but that sounds about logical.

Thanks a lot!

You definitely cannot mix and match these PSU and motherboards. That's why on my PSU board sales page, it says 'suitable for all 32/64/200/200E machines with the exception of the SECAM [motherboard] variant.

Regarding Parc Electronics - James Dexter might be the man to ask - he knows ex-DD and Race employees, and could well know some ex-Parc employees too. That said, I'm pretty sure this is them: https://find-and-update.company-informa ... ng-history. And they used to live here https://goo.gl/maps/q5TQJ67tj6KQ2MrN8.

Regarding the PIA, funnily enough, on the same industrial estate, there is a company called PIA Printing, who do accessible printing, like braille and large format. https://www.pia.co.uk. I know it's absolutely nothing to do with the SGS Thomson PIAs, but what a coincidence eh?

Thomson did make 6809s and 6821s - in normal and B speeds I believe - prefixed EF.

Hi Stew! It's been a while, you keeping well?

I've tweaked the wiki here - https://worldofdragon.org/index.php?tit ... d_Pictures - to reflect this. Initially it gave the impression that the SECAM board was simply another variant - and this definitely isn't the case! Anyone want to improve the wording, feel free.

Next time I take one of my Thomson machines apart I'll note the CPU - I suspect they'll have Thomson 6809s too. Given Dragon Data was quite happy to buy whatever was available and cheap, I'm not surprised some found their way across the channel at some point!

tjewell wrote: ↑Mon May 01, 2023 5:57 pm Hi Stew! It's been a while, you keeping well?

Hi Tony, I'm good thanks, apart from the day job sucking the life out of me. Starting to regret not working harder in my youth

Hope you're keeping well too. I really admire what you're doing on Twitter btw.

tjewell wrote: ↑Mon May 01, 2023 5:57 pm Hi Stew! It's been a while, you keeping well?

Hi Tony, I'm good thanks, apart from the day job sucking the life out of me. Starting to regret not working harder in my youth

Hope you're keeping well too. I really admire what you're doing on Twitter btw.

Edit: Double post. That's a new one!

Hello all. Here is the point of view of an old french user.
An interesting point is that the Secam Dragon is ready for 64 K, if you change the half good rams by 64K RAM. Nothing else to do.
Besides, the circuit of the motherboard is a bit different from PAL ones, it looks like a Dragon 64. And of course has that SECAM modulation with the typical green box which is a delay line.
In 1982, in France, the TV were B&W or SECAM. But a french law forced the sellers to put a PERITEL on the new TVs. To sell the machines in France, Dragon Data had to adapt.
How do I use my machine today ?
With a DragonPlus PSU (a bit modified, of course) and with a SECAM/AV signal sent to a TV. The composite video is not available as on the PAL machines. I take it before the modulator, adapt it with two transistors and send it on the DIN connector of the DragonPlus PSU Board.