Most liked posts in thread: Guys, there be a DRAGON in that there CAVE(!)

Hi, guys.

I had no idea, when I began this thread, that it would generate so much discussion! We've had some really good observations re. the 6809 family tree and links to Tandy CoCos and heaven knows what else in terms of hardware, software, compatibility and of course 1-2 interested parties.

Sad to say we couldn't quite strike a deal for Alex Drito (postage to Switzerland often the killer blow) but Vyper Rich in the end made the Dragon in Baz's cave an offer that the Welsh Wizard simply could not refuse (half a dozen leeks and a daffodil), so having waved its wings one last time here, the beast is now all boxed and heading out the door in the morn destined for pastures and a retro cave new...

All the best, Dragon 32 - I am sure Richie will look after you - and thanks to everyone on the forum who has chipped in and joined the discussion.

I don't know about you guys, but it has felt like a journey of discovery as I knew next to nothing about these machines beforehand whereas now I recognise another familiar member of the good old 80s retro micro family.

I hope you have a fine time 'roaring away' at chez Richie's...

 

Cheers Andy, I have been after another Dragon for a while ( you remember that last time I tried ) So when you mentioned you had picked up a Dragon I was as green as the Dragons colour video output I thought I had missed out on it when I started reading this thread but it worked out okay in the end.

When it arrives I will do a write up with some pictures and video.

 

I’m going to have a crack at making my own Joystick adapter based on the website...

https://vrai.net/retro/?p=112

 

Nicely put Matt..

I'm not sure about your theory regarding the internet, but who knows with so much WIFI; our planet must be radiating so much electromagnetic smog it's untrue.. Never mind me bouncing singals off the Moon; always wonder where the rest of the signal that missed the Moon has got to; some 25 years later, a fair way I guess.

*/ Begining of
Hmm lets think approx 300,000Kilometers a second.. in 25 Years that’s 788,923,800 Seconds

so about 236,677,140,000,000 Kilometres or 147,064,356,657,122 Miles ..

I'll just call that a long way, not a fair way...
End of /*
Back to Retro Computers.. and sorry the the mental / interlude

Just managed to bag an original IBM XT, and NO I’ll not be playing with it coz it's not going to get here for some time, also why I couldn’t afford a Dragon ops sorry a potential Dragon-co-co 2048 Thingamajiggy.

I've loads of stuff I want to get done and maybe for the last two weeks feeling much better (Fingers Crossed Famous last words and all that)

Well mucker's Well Andy knee deep in it at the moment !
73's (look it up)

 

We just need to know how many light years now Graham

 

Well I guess someone may have heard the dots and dashes 147 Million Million miles away but who knows

 

They could be walking among us...

 

Richie one for you :- wasn't a parrallel printer interface, but just an additional 8 bit interface for control..

 

You’ll have to take some pictures of your PC when it arrives Graham, not seen inside a XT before.

 

Well lots on retro computers, although I didn't see any detail on the upgrade, in terms a circuit diagram, just pictures and more cleaning and 'wrecking' the case for an Amiga PSU socket, the information being on another website via a link. No idea why he chose to change the case with a perfectly suitiable connector in place, even if the PSU was altered internally. Hey but that's me, And I do have cases with changes to them, although that won't be the case with the 800 I've got, even worked out I don't need to cut any plastics at all for the wiring going to the Incognito
The world of dragon seems a good resource though..
I've finally found this :-

 

Yeah I don’t agree with some of the stuff he did and the RAM can be upgraded via the Cartridge port these days. So getting everything all set for when Idris the Dragon arrives

 

I've still had no luck in finding the Magazine archived, however I do have both page 54&55, with I think only page 51 & 56 missing.
This gives details in both Fig. 2 & 3 of the connections to the Dragons expansion port, and also in Fig. 6 shows how to produce an extension connector.. so all the Hardware side is there just no Idea as to software, or even the address of the PIA/VIA added although this should match what ever the first cartridge area address is as a direct connection with no further address decoding that I can see.

 

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

 

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, 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.