[Coco] NitrOS9 build errors

[Bob Devries]

Gents, please give Tormod a round of applause for a job well done.

Regards, Bob Devries
Dalby, QLD, Australia

----- Original Message ----- 
From: "Tormod Volden" <lists.tormod at gmail.com>
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent: Sunday, January 19, 2014 8:27 AM
Subject: Re: [Coco] NitrOS9 build errors


> On Sat, Jan 18, 2014 at 9:24 PM, Darren A wrote:
>> On Sat, Jan 18, 2014 at 6:16 AM, Tormod Volden wrote:
>>
>>> On Sat, Jan 18, 2014 at 4:57 AM, Bob Devries wrote:
>>> > Hi Tormod,
>>> >
>>> > It seems strange that the dragon boot disk works when using the 
>>> > debugger,
>>> > but not otherwise. We really do need some real hardware tests.
>>>
>>> The code uses for instance a lot of NMI interrupts from the disk
>>> controller, maybe the emulation is not 100%?
>>>
>>> > Your suggestion of moving files around between the two disks sounds
>>> > workable.
>>>
>>> Done.
>>>
>>>
>> One thing I noticed in boot_d64.asm is that the interrupt masks are being
>> set (ORCC #$50) before preserving CC on the stack (PSHS Y,DP,CC).  This
>> means when the code later restores CC (PULS Y,DP,CC) the interrupts will
>> remain masked.  I don't know if any subsequent code expects the 
>> interrupts
>> to be enabled, but if so that could be a problem.
>
> Thanks for looking at this! It is indeed interesting, since the
> comment says "enable FIRQ". I tried using ORCC #$10 instead to not
> disable FIRQ but that did not make it work. Even adding ANDCC #~$40
> did not help.
>
> But when I looked at the XRoar trace to see where PC would jump into
> nowhere, I recognized the start of "REL" at $2602 and some
> instructions there that did not match the code as I knew it from
> rel.asm. Turned out that many writes to the PIAs went to page 0
> (direct page addressing, and without DP set). Actually in
> defs/dragon.d the PIA0Base and PIA1Base did not have "IO" ($FF00)
> added. Now I added the IO offset, and voila, the disk images are
> booting up in a "beautiful" high-resolution console!
>
> Tormod
>
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