[Coco] Nitros9 L2 6809 DSK image?

[Christopher R. Hawks]

On Wed, 11 Oct 2017 20:29:41 -0500
RETRO Innovations <go4retro at go4retro.com> wrote:

> On 10/7/2017 2:43 PM, Barry Nelson wrote:
> > So, did it boot?
> > How much memory does it show?
> > Type:
> >
> > mfree
> >
> >
> I am happy to report that I successfully booted Nitros9 last night
> and mfree reports 1944K free :-)
> 
> I added the Barry Nelson 512kB Emulation functionality tonight
> (sorry, could not resist), but currently have to determine how to
> enable/disable it.  I initially put it on $ff91 bit 7, but at least
> Nitros9 resets that flag before booting to mem check, so it
> effectively turns it off :-)  I think I'll implement my "port
> knocking" approach for the emulation enable (like I did on CocoFLASH).
> 
> I assume 4MB works, and I have the NoCan support in, but I need a 
> Nitros9 SDC image to try that will test it.
> 
> The issue at Tandy assembly was a stupid error:
> 
> if(flag_crm & cpu_address[12:4] == 12'hffe)
> 
>     data_bank = 9'hfe;
> 
> Should have been:
> 
> if(flag_crm & cpu_address[12:8] == 8'hfe)
> 
>     data_bank = 9'hfe;
> 
> Which I fixed last night, only to get an immediate screen
> corruption. On a hunch, I asked where OS9 screens are kept, and the
> answer was "top of memory".  My working firmware did not have the
> DISTO Video Bank code in place, and I watched Nitros9 try to store a
> $03 into $ff9b. Since my firmware didn't watch for that, Nitros 9 was
> putting the screen at 2MB-8kB and I was pulling screen data from
> 512kB-8kB.  After implementing that register, all works.
> 
> Jim
> 
> 

    First in line!!! Jim tell me where to send my money.

35 years ago, I paid $160 for _64k_ of memory for my original CoCo.
And it's still running...


Christopher R. Hawks
HAWKSoft
-- 
They both savoured the strange warm glow of being much more ignorant
than ordinary people, who were only ignorant of ordinary things.
		-- Terry Pratchett, Equal Rites
----------------------------------------
       \   ^__^                         
        \  (oo)\_______                 
           (__)\       )\/\           
               ||----w |                
               ||     ||