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Hi - I just wanted to let you all know that I have asked Phill if I can run a batch of his excellent RGB boards - and he has agreed. It will be a while before I can do so - and I have no idea about pricing yet. I will put a seperate post in the Hardware forum. I don't want to curtail any development...

Very interesting to see the schematic. It seems more simple than the board implies though. For instance, where are all of the RF tunable inductors and the delay device? Or is that just for SECAM RF?

Very interesting to see the schematic. It seems more simple than the board implies though. For instance, where are all of the RF tunable inductors and the delay device? Or is that just for SECAM RF?

6x09 SuperSprite FM+ (MPI Mode) !P2/!SCS FF56-FF57 YM2413 ports FF58-FF5B V9958 ports FF5C-FF5D YM2149 ports FF5E Video select port (bit 0) 6x09 SuperSprite FM+ (Native Mode) FF76-FF77 YM2413 ports FF78-FF7B V9958 ports FF7C-FF7D YM2149 ports FF7E Video select port (bit 0)

Whilst I'm on the subject of the DragonPlus boards, I have also discovered another tiny error that Compusense seemingly made 'back in the day'. The 74HCT165 (IC23) chip which turns the character mappings into 0s and 1s for the screen display has an input called "Serial In" on pin 10. I have noticed ...

I have finally solved the issue of only Hitachi EPROMs working in the DragonPlus. It seems it was an issue unique to MY board only - so maybe people out there have been wondering what on earth I have been prattling on about. Anyway - this video will show and explain the issue and also describe the f...

There's two ways to solve the CocoSDC issues with the DragonPlus (or OS9 in general). First would be simply to BANK to another DOS version before booting. So you'd start in DOSPLUS. Then... SDRIVE 1,"OS9DISK.VDK" BANK 3 (I have Eurohard DOS in ROM bank 3 of the Coco SDC) The machine cold boots into ...

Hi, I have one of these, and though fascinating in itself (I wanted the board because of the motherboard layout - I didn't realise beforehand that these were the SECAM machines), the RGB output simply was not as good as I expected. The main issue I found was the excessive blue on the screen. I have ...

Following on from my post about the pull-up resistor solution (the one which seems to make OS9 loading more reliable - especially with the D+ board), I have now added a descriptive blog to the website: https://www.dragonplus-electronics.co.uk/6809-pull-up-resistors/ . This describes at a high level,...

Some of you will be aware of the issues that have been experienced with the Coco SDC and OS9. It has often meant mounting the VDK in DOSplus and then BANKing across to another DOS prior to BOOTing the image. Finally, the root cause of that has been identified, and I have prototype boards which demon...