Attempting to get a DragonPlus board going ...

[tjewell]

Hi all!

I've just got hold of a Dragon 32 with a DragonPlus board in it, and I'm trying to get it working. The Dragon itself seems to be working fine, which is a good start, and I've just downloaded these files from the archive:

"DragonPlus Updates (1985)(Compusense Ltd)[!][FLEX].zip"
"Flex - System v2.0.0 - DBASIC v1.7 (198x)(Compusense Ltd)[DPLUS].zip" (which, interestingly, unpacks to be called "Compusense - Flex - DragonPlus Update.VDK")

If mount either disk, and do a 'BOOT', I get the red boot screen that @pernod70 describes here: viewtopic.php?f=5&t=5603&hilit=dragonplus#p15792

Now, if I unplug the composite connection from the back of the Dragon and plug into the socket made for the DragonPlus, my screen flickers very quickly and the TV makes a high pitched whine. This is just a normal composite connection isn't it? The DragonPlus manual says "Any monitor my be used with this interface, provided that it accepts 75ohm composite video and has controls to adjust width, height and synchronisation". Okay, my TV doesn't have those controls, but it should show some output, shouldn't it? The manual recommends a Philips 7502 monochrome monitor, which I might be able to borrow from the museum, is it likely to be that simple?

Any thoughts?

Cheers,
Tony

[robcfg]

Hi Tony!

It would be nice indeed if you could check with the mentioned monitor.

I have a DragonPlus board that Manu sent me and when I tested it I couldn't get a picture either. I never thought it could be that the output wouldn't suit a standard crt tv...

Good luck!

P.S. Oh! and take some pictures of the board, just in case

[sorchard]

Hi Tony,

Nice find!

Forgive my ignorance on the subject, but I'm wondering if you need to run software specifically tailored for a 32K machine. The manual seems to suggest that all the bank switching occurs in the lower 32K, which strikes me as a tricky setup if all you have is 32K.

Anything that prevents the 6845 registers getting programmed properly could result in no display.

[robcfg]

I think that maybe the board doesn't do anything until a suitable program initialises it.

Tony, can you try the disk version of Edit+?

It has support for the DragonPlus board, so with a bit of luck everything's working.

If it works, we want pictures!

[Pernod70]

Tony, can you try the disk version of Edit+?

It has support for the DragonPlus board, so with a bit of luck everything's working.

I can confirm that disk version works in MAME, use EDIT128 with DragonPlus.

You say you have a Dragon 32 though, always thought the Plus board was for Dragon 64.

[tjewell]

Sorry all - wrote a post then deleted it when I realised I was talking nonsense!

My machine has a 32K motherboard, definitely, but it might have been upgraded to 64K. Let me check, I'm not near it at the moment.

@pernod70 - what I was going for is this - viewtopic.php?f=5&t=5603&hilit=dragonplus#p15792
Ie. Flex message on the Dragon (which I get), Flex login on the DragonPlus (which I don't think I get). Which copy of Flex did you download from the archive to get here?

I'll try Edit+ too, thanks for the suggestion.

Right, now off to the museum to scrounge a monitor, just to double check that's not the problem.

[tjewell]

Okay everyone, lots of progress!

First off, my machine *is* a 32K system, which surprised me. The advert http://archive.worldofdragon.org/index. ... onplus.jpg says 'requires a 64 Dragon', but the installation notes http://archive.worldofdragon.org/index. ... rams02.jpg say "is fully compatible with both 32K and 64K Dragons".

Next I plugged in my new dinky little monitor, but still nothing - but now I suspect there's an issue with Flex and the fact my machine is 32K. So as @robcfg suggested, I tried Edit+, and oh my gosh, it actually works! (I don't know how to use Edit+, but I can come back to that).

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So now I'm wondering if the reason Flex didn't work is because this isn't a 64K machine. Now, I don't want to break this machine by removing the board and testing it in the 64K, so I'll see what I can work out with an emulator. @pernod70 - I know absolutely nothing about Mame - how would I get an emulation of a DragonPlus system up and running?

Thanks for your help and suggestions everyone - I think this is the first time I've ever seen a real, running DragonPlus board!

[tjewell]

Ah, as ever, I should have RTFM. Quoting our own archive page - http://archive.worldofdragon.org/index. ... ragon_Plus - it says "Both the OS-9 and Flex implementations used the additional 64KB as a RAM disk so the main OS ran completely from RAM". So that's why it's not working for me, it would require 64K in the host machine for this to work. A shame, 80 column OS/9 would have been rather nice, but I don't want to risk damaging my DragonPlus board or my D64 by swapping it over. Off to read the MC6845 datasheets to see what I *can* make this machine do.

[Pernod70]

@pernod70 - I know absolutely nothing about Mame - how would I get an emulation of a DragonPlus system up and running?

Do you still want to try MAME? I don't support a Dragon 32 with Plus board so you won't be able to replicate your setup.

[tjewell]

Well, I'm confused. This is the problem with the machine being in my office, and I'm supposed to be at home with my family - there's only so many times I can 'pop out to the shops' and quickly nip into the office to check things! And it means I miss stuff ...

It now looks like my machine might be 64K after all - an eagle-eyed reader on Facebook noted that my RAM chips are socketed, and indeed they are. Closer examination shows that the second row of RAM chips have been removed too (see photo below) and the new chips are KM4164As - which would imply 8 x 64K = a 64K Dragon. I'd like to prove this, but I'm not sure how - I guess I could write a small m/c program to switch the ROM out and see if there's RAM there (hunts for reminders on how to do this).

But ... if it is a 64K, my nice simple reason for Flex not running (I don't have enough memory) disappears and means I need to do more digging. Oh well!

As ever, any pointers or suggestions gratefully received!

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