archive.worldofdragon.org

Can I throw my interpretation in the mix then? Not *just* MMU, this is a replacement for SAM, RAM, ROM and VDG Using the SAMx8 as a starting point I have the usable RAM expanded to 2MB using 8K page sizes. The pages are allocated against 4 "tasks", a supervisor, two operational tasks and the video s...

Update on progress - the ATX machine is running, I have everything except the cartridge port, real time clock and expanded audio built and working. The keyboard interface is waiting on a single chip to arrive (basically an Arduino performing the translation of a PS2 keyboard's serial data into somet...

The crystal is just a tuned chunk of quartz inside that can, and it just a matter of packaging as to what size is needed and there are variations but fundamentally they are all much the same. An oscillator is a different kettle of fish and should produce a stronger logic level signal, these normally...

Easier to find but I'd hoped for a nice cheap option...

It does give me a viable price cap on the replacement device

Did you get anywhere with this? Just looking at the board it looks like there is a fair bit of tarnish on the chip legs in places, especially where they are in sockets. This *will* stop things from working properly although I do note you've swapped out the socket and chip for the LM1889 with no impr...

Pretty much ready to spin this up for real - I have CPU, SAM, PIAs, RAM, ROM and VDG all hooked up. The LA board is a bunch of spaghetti and a tiny bit too wide to fit nicely... and certainly doesn't fit in the ATX case (again I didn't think this through and I need to make a different arrangement of...

I'm pretty sure this has been discussed before (can't imagine it hasn't) but I'm trying to detail a minimal method of converting a Dragon 32 PAL machine to output NTSC. I've (sort of) done this on my reproduction boards but want to check the theory of the process with the collective Step 1 - Rewire ...

All of that would be great if I'd order 32 pin connectors... too much on my mind - that's my excuse and I'm sticking to it

The IO and VDG cards only made it as far as Hillingdon (Heathrow for those that don't know London) so no more build this weekend The 40-pin connectors for the logic analyser board have turned up this morning though so I have a fighting chance of actually doing some real testing of the built-up compo...

So here's my plan - write $AA to every byte in the lower 32K to initialise. Then loop through the same memory, read each byte and test for $AA then changing $AA to $55. Do the same again swapping the two values. Any errors (ie reading an unexpected value will result in the upper byte of the test add...