Guys, there be a DRAGON in that there CAVE(!)

IDRIS is most definitely on her way, Richie. After the CO-OP's lack of courier labels on Monday, she was dropped off Monday night and will have left Hull yesterday morning, mate.

You'll know when she's arrived with you there...



So ensure you have your sprinklers set to the....

MAX!

 

Hi Richie
If you can get hold of a decent schematic, I'm happy to help you with a small circuit to add an additional PIA chip.
I've just found among the lost Items, the original instructions for the C.U.P.I.D. Centronics Printer port upgrade.
and guess what? uses a recomemded 6821 sat on top of the 6522, all the Power Address and Data lines soldered directly, and most of the control lines Bar Chip select. all PORT A & B plus CA0,1 CB0,1 left out to connect what ever you choose.
In this case the additional Chip Select line connected to the O.S. Controller at one of either D1xx,D5xx,D6xx or D7xx but as not in front of me can't tell you which.

It would be nice to see some close up internal shots of the Dragon maybe four photo's to cover the whole board at High Resolution.

 

The Dragon archive has hires shots of the PCBs of the various models...

https://worldofdragon.org/index.php?title=Motherboard_Pictures#Dragon_32_-_Mark_II

 

Yea But that's not your Dragon

 

Hey Graham,
Here is the best Dragon schematic I can find...

https://drive.google.com/file/d/1T7FuX0wJZBgClFuM3QRTKpUeCzRK8jZm/view?usp=sharing

 

Thanks Richie, I've saved that now, looks like I need the memory map as well, seems' the SAM chip is responciable for this did find this https://www.onasticksoftware.co.uk/dragon/dragonhw.htm
This helps, and can now see the previous Parrellel Port would sit at C000-FF00h and echoed many times over.
I'll explain at another time.
Would be better to decode in I/O area FF00-FF5Fh just need to find what space there is to slot it in.

How about buying a few more and linking them
https://www.onasticksoftware.co.uk/dragon/netwrks.htm

 

Here’s the memory map mate,




upload a picture

 

That's a start but i'll need to know the decoded Addresses of the PIA's the Video Chip etc. these will have as an example for the PIA only 4 register addresses say E000h-E003h and the second one at say E100h-E103h etc.
They will exist in the bit E000h-FFFFh in the memory map showing.

The Atari chips are well documented, at D0xx(GITA),D1xx, D2xx(POKEY) D3xx(PIA) D4xx(ANTIC),D5xx(CARTRIDGE) etc some chips some unused and other when a cartridge is inserted such as the OSS Cart at D500,D501,D509

Its this level I'll need

 

Do you mean this?

 

These pages were taken from this book Graham.

https://drive.google.com/file/d/1lYXf5xPR4dwaGq5Pbty5-cw0_QaMOWSS/view?usp=sharing

 

Hi Richie
That looks to be the level of information needed, I'm at hospital waiting for a blood test at the moment, so can't download (I did try ) phone didn't like it.
I'll check it out when home, it would be great if either of the PIA's are socketed, as would make a nice easy conversion.
What were you thinking of using the additional posts for?

 

Idris the Dragon has landed!

 

All downloaded... So how is the firey beast ?
P.S are the PIA's in sockets ? what revision board, 16 Memory sockets, 8 etc etc.

Yea I'm excited for you !!

 

It’s an Dragon 32 MKII PCB and is an Issue 5 so there is a photo of this type of board in the archive and the PIA’s are soldered in and not in sockets. So it looks like this...



Sadly there is a problem with Idris that I have messaged Andy about so until he is aware I cannot go into details.

 

Oh thats a shame
I've had a look at that book and extracted the information I needed attached..

 

Hi, fellas.

Just got home tonight to a fully formed ROOF now up on our extension which has cheered Bev and I up no end (yesterday we had monsoon like rain and no-one enjoys their home getting flooded whilst works like these are ongoing...





So we can now get on with the builders blitzing the kitchen and us getting the kitchen delivery date now finalised.

Just told Richie that I expected his email to say, hopefully, it's all here well and good, arrived fine in one piece and fully working but... life aint like that, is it?!

He says there's a problem with the sound... ie. there aint any.

As I've told him, hand on heart, I've never had a Dragon so I have no idea what the sound is like but when the beast was here I hooked it up with an old 5pin DIN lead to x2 phono plugs which gave me a reasonably stable display and some sound... I agree, it wasn't a loud sound and I had to turn my TV volume up some way to hear it but there was some sound but I suspected my spare lead from the bottom drawer as probably being the culprit but clearly there's more to this than meets the fiery eye.

I've advised Richie that if the beast doesn't roar (should it?), ie. can't be fixed then return it and I'll advertise it with this as a definite fault on Feebay and we'll say no more.

Hand on heart, fellas, I would never send 6.5kilos of anything to anyone claiming it was 100% when it wasn't as I definitely hold with the maxim that you treat others how you wish to be treated and we all know how annoying it is to receive faulty goods.

Richie, apologies, fella - send it back if it's no ruddy good, mate and I will refund what you have sent me already.

Some days, it does nowt but rain - Ull yesterday...


ABOVE: Commentary provided by Phil Applecart

 

Andy, ... Mate I know you would never do that so don’t stress. These are 35 year old ( or more .. this dragon is from ‘83 ) and sometimes chips fail.
The weak audio may have been a precursor to the audio failing so who knows. The Dragon ( hereafter referred to as Idris ) thinks it is making a noise as the BASIC command SOUND makes Idris do something for a while. So I will dig out my logic analyser if the chip replacement doesn’t work.
So far I have tested the continuity between pin 10 of the CD4529 chip which is the sound output.
Pin 11 of IC35 ( 6821 PIA ) to R56 ( Bitsnd ) which is also liked to pin 10 of the 4529 mux.
Continuity from pin 10 to the RF Modulator and AV socket is also fine.
So plan is to replace the 4529 IC and see what happens, apparently they are prone to damage as it also handles the joysticks as well and is a point of failure on Dragons.
So watch this space...

 

Rich,
Good luck and once more apologies - we can only hope you make a breakthrough.
Knock off the final price whatever you end up shelling out for in spares and if it still doesn't make any sounds... send the Idris back to me for termination on Feebay!
Apols, pal and let's hope for a happy outcome as a Dragon with no voice is no chuffing good to anyone.

 

I'm sad about the 1050 I sent Richie, As Andy will be aware, I try and send things in a secure way so no damage can be done. However the PSU I sent, ended up with cracks in the outer casing. It's a shame was the only original that hadn't been opened by drilling the rivets out.

Richie very kindly accepted it, and I did discuss another one being sent out. Reminds me He said he was going to try epoxy, I'd better reimburse him for that.

In regard Sound on the Dragon the circuit is very very simple, it uses 6 bits PA2-PA7 of one of the PIA chips IC35 on your board, fed to IC 34 a 4050 CMOS buffer chip with 6 different value resistors on it's output, 10K, 20K and roughly doubles each time.

I'll attach the bit's of the circuit; now you found good diagrams
It should be easy to trouble shoot and can offer help if you decide to attempt a fix.
i.e. check all PIA pin outputs using Pokes to set each bit (may not need this), move on to 4050 if all o.k, last thing check resistors, this then leads to the sound switching chip IC 20 a 4529 Analogue switch which selects the source of the sound and feeds all to a compartor. One half of IC25 an LM393.





EDIT
This was sent before I'd seen Richie's post and Andy's reply, so it looks well in hand already !!

 

Thank you very much for your hints, tips and guidance too, Graham.

I wouldn't have had the foggiest where to start but as you say, looks like Richie's on his way with replacement chips etc.

I can certainly vouch for your excellent standard of way above the normal quality of packaging and securing goods sent through the post, Graham, so any damage to the 1050 PSU can only have occurred due to extremely heavy handed idiots being let loose with the fragile packages and parcels - and no one can legislate for that, this end of the courier chain.

Once more, many thanks to all on this one and let's hope Idris breathes again and utters forth a roar before very much longer.

I'm sure Richie will keep us all in the loop on this one and here's hoping, fellas.

 

Big thumbs up Richie... you can buy some glue now..or maybe just a 4529, at least you can get it already by clipping it out and adding the socket ready and waiting..

Andy that's a fair amount of watery stuff, falling from above up there in Ull..

 

Idris is fixed and we have sound again, nice and loud. Haven’t tested the sound through the cassette input but should be fine as we have sound from the computer.
So it was the CD4529BC mux that had failed and the total cost was £3.00 for two 4529’s ( I always get a spare )
So job done and a H63c09 CPU ordered, 6809 programming books downloaded and all set for some experimentation. Plan is to recap the power board and mainboard later and add sockets the 6821’s as well, just some general maintenance. To have got to the age of 37 and have a £1.50 chip fail is not bad going.

 

Thanks for the “Glue Money” Graham, the Araldite has set like concrete now and the power supply case is stronger than before now

 

RICHIE - the boy done good - you are a genius and a frugal one at that - what a relief that the problem wasn't a major meltdown or colossal cash cow. Big relief this end as I'd told Bev that Idris wasn't well and that the beast could be coming home to our cave once more and she shot me such a look of sheer menace that my Maltesers melted and my Bounty bar broke beyond bite-sized chunks... Fella - GREAT NEWS - I just hope Idris is now happier in your home as it sounds like you've already loads of great upgrades planned for her whereas here she was sat under an Oric, here, waiting for Bev to hurl the whole heap of my sweet, saucy beauties into the skip at the back of our house(!!) ;-)



PS.Thanks for the payment too, Richie - best wishes, enjoy mate, and have a top weekend tinkering.

 

Richie

Yey nice one.

sounds a great plan, I wonder if it's worth buying one of the CPU protectors as well, based on the fact your going to be playing with the guts?

Is the Dragon fitted with 6821's or 68B21's the 2MHz is the later one?
Be nice to know what the most useful extra you'll be adding will be? an SDC cart (think thats right)
I'm also glad about the PSU caseing, And I guess I screwed up and didn't wrap in in enough bubble wrap, mind you kinda went over board with the 1050..

Your most welcome, sorry I'd not done it before, but hope you are pleased with it's operation.

Andy
What do I see wrapped up at the bottom of that pile next the Dragon, and another tucked over the back as well?
Least the dust wont get in