[Coco] MC6829 Memory Management Unit

[Dave Philipsen]

This sort of functionality is fairly easy to implement with an FPGA or CPLD. If I had the time to fiddle around with the OS9 kernel I would implement this on my dev board and see how it works (the idea of having 32 task registers and 2K blocks). But alas, I think the software effort with OS9 would be more time consuming than the writing/testing of the VHDL code. 

-Dave Philipsen

> On Oct 10, 2022, at 7:36 PM, Joel Rees via Coco <coco at maltedmedia.com> wrote:
> 
> 2022年10月11日(火) 9:04 Dave Philipsen via Coco <coco at maltedmedia.com>:
> 
>> Yes, I was just following the original thread from Walter. I don't think
>> he mentioned anything about a two task limit for OS9. We all know that
>> OS9 manages up to 32 tasks. We was referring to a two task limit in the
>> GIME hardware. And his comparison of maximum memory between the GIME and
>> the MC6829 was correct. GIME=512K, MC6829=2048k
>> 
> 
> The app note has a bit of rather awkward wording that makes it sound, if
> you're not reading carefully, like it requires 8 of the 6829s to actually
> address the full 2M. It also says the MMU has to be "reprogrammed" to get
> around that max or something like that, which is more unfortunate wording.
> 
> Talking about shouldas, I should have offered to rewrite that for them back
> in 1981.
> 
> -- 
> Coco mailing list
> Coco at maltedmedia.com
> https://pairlist5.pair.net/mailman/listinfo/coco