Search found 413 matches

by sorchard
Wed Apr 01, 2020 9:24 am
Forum: Dragon Hardware
Topic: Dragon64
Replies: 7
Views: 1486

Re: Dragon64

My guess is ROM or RAM seems most likely, the orange screen being a symptom of a crash rather than a direct symptom of a fault. If you're able to get your hands on a cartridge based machine code monitor, (and if it works!), you would be able to inspect the rom contents and check out the ram. I remem...
by sorchard
Fri Mar 06, 2020 11:12 pm
Forum: Dragon General
Topic: DriveWire server and memory test utility
Replies: 2
Views: 208

DriveWire server and memory test utility

I've finally got round to publishing a couple of Dragon projects I've had kicking around for a while and thought they might be useful to others. Firstly we have yet another Python DriveWire server. I wrote this because I needed something relatively simple that supports the DriveWire hardware and sof...
by sorchard
Fri Feb 21, 2020 10:55 pm
Forum: Dragon Hardware
Topic: Dragon 32 jumping to buff mode spontaneously?
Replies: 17
Views: 560

Re: Dragon 32 jumping to buff mode spontaneously?

Where I've seen colours messed up almost exactly like that before is on the older motherboards that have two variable resistors (pots). All boards have a pot next to the power connector. This adjusts the video DC level. Older boards have a pot labelled 'RV1' just to the left of the 6847. This adjust...
by sorchard
Sun Feb 09, 2020 11:28 pm
Forum: Dragon General
Topic: Dragon Pepper by Genesis Project - a new Dragon 32 demo
Replies: 14
Views: 765

Re: Dragon Pepper by Genesis Project - a new Dragon 32 demo

sixxie wrote:
Sun Feb 09, 2020 7:05 pm
No idea why we don't get even crunchy audio out of emulators, mind.
It took me a while to figure out: The audio is on the tape, and not produced by the binary. Still cool though :)
by sorchard
Sun Feb 09, 2020 11:08 pm
Forum: Discuss This Site
Topic: New Member, long time Dragon 32 owner
Replies: 17
Views: 1824

Re: New Member, long time Dragon 32 owner

Your composite output actually doesn't look too bad for a Dragon. The MKII machines had a sharper image than the earlier models thanks to an improved circuit. Not sure what would cause the ghosting on the right, other than the video signal being too high and causing a bit of saturation somewhere. It...
by sorchard
Sun Feb 09, 2020 10:38 pm
Forum: Dragon General
Topic: Dragon Pepper by Genesis Project - a new Dragon 32 demo
Replies: 14
Views: 765

Re: Dragon Pepper by Genesis Project - a new Dragon 32 demo

This is superb! Every part of it: Coding, artwork & music. I've tried it on real hardware and it looks & sounds great :D
by sorchard
Thu Feb 06, 2020 9:42 am
Forum: Dragon General
Topic: A 6809 Single Board Computer
Replies: 19
Views: 1141

Re: A 6809 Single Board Computer

Y5 is the output you want to use as the missing /CART. This would go to the output enable and/or chip select of the external ROM. The other LS138 outputs are not necessary, but possibly useful for other projects. Regarding playing Dungeons of Daggorath, if you're talking about the original game on c...
by sorchard
Wed Feb 05, 2020 2:04 pm
Forum: Dragon General
Topic: A 6809 Single Board Computer
Replies: 19
Views: 1141

Re: A 6809 Single Board Computer

A bit of extra decoding is required to put a cartridge ROM into the unused part of the memory map at 8000-9fff The easiest way I can see is by feeding E, RW, A15, A14 & A13 into an LS138 decoder to generate the OE signal for the ROM. You can even get a couple of bonus signals that are active during ...
by sorchard
Wed Jan 22, 2020 5:02 pm
Forum: Dragon General
Topic: A 6809 Single Board Computer
Replies: 19
Views: 1141

Re: A 6809 Single Board Computer

If you have a 68B50 uart then it should run fine at 2MHz. You would just get a weird baud rate of 125k, which may or may not be usable with an FTDI cable, I'm not sure. You may even be able to overclock it a little if you can find a suitable crystal (Maybe 8.9MHz?). I happen to have a terminal that ...
by sorchard
Wed Jan 22, 2020 1:46 pm
Forum: Dragon General
Topic: A 6809 Single Board Computer
Replies: 19
Views: 1141

Re: A 6809 Single Board Computer

Cool project. In fact I found quite a few interesting things to read about in your blog. For operation at 3MHz, the uart may spoil the party somewhat and require a new board design. You would need a device that is rated for 3MHz and it would require a separate crystal to get a standard baud rate, na...