Search found 83 matches

by dublevay
Tue Jul 27, 2021 4:03 pm
Forum: Dragon Hardware
Topic: Dragon 32 RGB SECAM and video tests
Replies: 24
Views: 2404

Re: Dragon 32 RGB SECAM and video tests

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?
by dublevay
Tue Jul 27, 2021 4:03 pm
Forum: Dragon Hardware
Topic: Dragon 32 RGB SECAM and video tests
Replies: 24
Views: 2404

Re: Dragon 32 RGB SECAM and video tests

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?
by dublevay
Fri May 28, 2021 6:52 pm
Forum: Dragon Hardware
Topic: Dragon expansions - FF00 page ports
Replies: 8
Views: 1111

Re: Dragon expansions - FF00 page ports

Dragon MSX 2+ MPI Mode !P2/!SCS FF56-FF57 YM2413 ports FF58-FF5B V9958 ports FF5C-FF5D YM2149 ports FF5E Video select port (bit 0) Dragon MSX 2+ Native Mode FF76-FF77 YM2413 ports FF78-FF7B V9958 ports FF7C-FF7D YM2149 ports FF7E Video select port (bit 0)
by dublevay
Tue Apr 27, 2021 6:54 pm
Forum: Dragon Hardware
Topic: DragonPlus Original Board 'Fault'?
Replies: 2
Views: 787

DragonPlus Original Board 'Fault'?

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 ...
by dublevay
Tue Apr 27, 2021 6:52 pm
Forum: Dragon Hardware
Topic: DragonPlus EPROMs
Replies: 0
Views: 648

DragonPlus EPROMs

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...
by dublevay
Tue Apr 27, 2021 6:50 pm
Forum: Dragon Hardware
Topic: Coco SDC & OS9 Boot - Solved
Replies: 2
Views: 1415

Re: Coco SDC & OS9 Boot - Solved

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 ...
by dublevay
Sun Apr 11, 2021 11:54 pm
Forum: Dragon Hardware
Topic: Dragon 32 RGB SECAM and video tests
Replies: 24
Views: 2404

Re: Dragon 32 RGB SECAM and video tests

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 ...
by dublevay
Sat Jan 23, 2021 5:09 pm
Forum: For Sale
Topic: CPU pullup solutions
Replies: 0
Views: 1258

CPU pullup solutions

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,...
by dublevay
Wed Jan 20, 2021 12:12 am
Forum: Dragon Hardware
Topic: Coco SDC & OS9 Boot - Solved
Replies: 2
Views: 1415

Coco SDC & OS9 Boot - Solved

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...
by dublevay
Sun Jan 10, 2021 4:00 pm
Forum: Dragon Hardware
Topic: Problems with DOS using an Y-type connection
Replies: 42
Views: 13690

Re: Problems with DOS using an Y-type connection

At bluearcus' suggestion (well, I think that's him) I have now put together a somewhat neater pull-up solution which would mean that the Oojamaflip would still work with the DMSX2+ and CocoSDC as is without needing additional pull-ups. It's a 6809/6309 adapter with the address and R/W pull-ups incor...