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sixxie wrote: ↑Mon Jun 08, 2026 4:06 pm You would think they'd override those in OS-9 to make things a bit quicker - I'm sure they'll be doing so in NitrOS-9...

..ciaran

I believe they indeed do (OS9 and NitrOS9 both)

Otherwise, you have to waste all of 0-1fff to preserve the vectors.

Jim

The reason seems to be the fact that REL sends value $DC to FF90 Working with the iMMUnity module we use to send $40 or $48 instead, so I have changed $DC to be $48 (in the CCSWITCH.BAS program) and that way I have verified that the values POKEd to FFF0... are preserved If you could help me out wit...

He posted on FB a bit ago about it:

https://www.facebook.com/groups/dragon3 ... 556877046/

I ask for grace on the code quality of my contribution. To assist Pere in testing code on his Dragon with the MMU, I quickly converted the Verilog to C to get the patch going. Once Pere and John prove out the correctness of the HW implementation, I will work to clean up the code.

Jim

OK, don't bite me... https://docs.google.com/spreadsheets/d/e/2PACX-1vSV9pZwTCZp1znalJSEY0smTu5m1WvSgWehv29hd6jRWGaI8VGxhoWdUfvuli40WYeqLR4oHaX4lL6X/pubhtml?gid=0&single=true Hehe. A few notes on CoCoMEM Jr: Full specifications and technical info not available, but video memory access is problemmat...

For your spreadsheet: CoCoMEM Jr replicates the CC3 MMU (8kB pages, multiple tasks, optional common memory at $fexx, etc.) It currently sits in the CPU socket The HW design supports 14 bits of MMU address extension (128MB of linear address space) with 2 "special" bits reserved for memory protection,...

I think Jim Brain (Go4Retro on here) said his project does interface to video, but I can't remember how. Maybe interposes the SAM as well as the CPU. My effort is a work in progress, but it currently creates a "hole" in the address space for pages 38-3f and passes memory requests to those memory lo...

Hi all! There was much talk of MMUs at this year's Meetup (a particularly good one I thought this year!), so I was wondering if someone might take a stab at summarising the different options in a way that even simple people like me could understand. I'm happy to see the interest. The options I can ...

Wow, you weren't kidding. That was hard to read (up to the 1989 articles, but have not waded through them yet.

Is there a handy link to the respective articles and any errata available? I ask because I have a CoCo1/2/Dragon MMU solution that replicates the CC3 MMU config, and running OS9L2 on it is I think the true test of how well it works. Pere's asked to test a unit, but since there's prior art on this, m...