On 8/6/2012 3:12 PM, Steven Hirsch wrote:
Boisy is most definitely the right person to ask about the intricacies
of OS-9/NitrOS-9 and 6809/6309 assembly programming. He's forgotten
more about it than I'll ever hope to know.
I'd love to see a minimum of 512k on such a card, and it goes without
saying that I want one :-).
I agree, the same way as my PCPI clone takes either 128K or 512K chips.
One question is how to implement the memory management. There seems to be a
standard in the 6809 world where the space at $FF00 (?) contains 16 write-only
registers that map logical 4K blocks to arbitrary physical memory. That would
require a lot more resources to implement than is available in simple CPLDs
easy to hand solder. Another extreme is a single 32K block mappable to
physical RAM. I wonder what is the minimum for OS9 level 2? I guess reading
the CoCo 3 manual may help.