[Coco] NitrOS9 build errors

[Tormod Volden]

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