archive.worldofdragon.org

Has anyone done anything with getting OS9/level 2 working on a modded D64 recently?

I was working on this 20+ years ago, but found it hard to get hold of the OS in the UK, and I made some fundamental mistakes, so it never got completed.

I'm thinking of giving it a go again, using Nitros9, but working on the MMU totally differently from what I did then, but was wondering if anyone else had done anything with it. AFAICT, the CoCo3 had a considerably different memory map (and different graphics?), so I believe that Nitros9 will need modding to make it work (or it would need too many changes to the D64 'base' operation AFAICS).

So, if anyone else has got it working recently, I may work on what they've done. I don't want to resurrect what I started on 20 years ago, because the world has changed now, so I'm thinking of using a 512kB SRAM IC and a cheap FPGA rather than all the discrete logic & banks of DRAM ICs I was using then.

OS9 Level 2 for the Dragon is on the top of my Dragon wishlist
There has been some discussion on the issue of Bringing OS9 Level 2 to CoCo2 and Dragon on the CoCo list a few months ago.
See here:
http://permalink.gmane.org/gmane.comp.h ... coco/89974

Hmm, this looks interesting

- A Coco3 on an FPGA
http://www.tandycoco.com/forum/viewtopic.php?f=80&t=65

As it happens, the board they're using - the Altera DE1 - is the board I'm fiddling with. They've put pretty much a whole Coco3 onto the FPGA (running at 25MHz). My plan is to put the MMU, RAM, fake-disk controller (and disks stored on SD card), VGA output onto the FPGA and connect it to a D32/64 via the cartridge port going to the GPIO ports on the development card.

I have to be careful to keep going, because part of what I'm doing is to learn, and for the fun of doing it, where I could just copy their Coco3-on-FPGA and have the end result, but the journey is where the fun is for me

But, they're getting a 25MHz CPU, I'll still have the 0.9MHz CPU (possibly 1.8, since you'll be able to switch out the VDG), but I'll still have the 'historic' bits of the old Dragon, they'll just have a 'fake' vintage computer

At least I now know that the Cyclone II is up to the task, since they've implemented the whole Coco3 (including, CPU, PIO, etc) and more and I just want to implement the MMU & some I/O.