[Coco] Programs for NitrOS-9

[Gene Heskett]

On Tuesday 29 April 2008, L. Curtis Boyle wrote:
>On Tue, 29 Apr 2008 12:37:21 -0600, Gene Heskett
>
><gene.heskett at verizon.net> wrote:
>> On Tuesday 29 April 2008, Diego Barizo wrote:
>>> I was thinking more on programs that run in OS-9, but not on NitrOS-9.
>>
>> That should work, with possibly a <10% speed improvement.
>>
>>> Maybe it's just that I haven't been able to get them to run...
>>> Most of the times I just try booting from NOS-9, and try to load the
>>> program from the original application disk, that probably came with a
>>> customized boot for OS-9.
>>
>> That is quite often the case, there might be drivers in their customized
>> boot
>> that are not in your nitros9 boot.  vfy or ident should show those diffs
>> though, and another boot might be constructed to add the missing stuff.
>>
>> ISTR there was a 1 byte patch to runb that played a minor role in this
>> too,
>> but I can't recall the details now.  Perhaps someone else can find that?
>
>    It had to do with error trapping, trying to read the error code
>register off of the stack. Because of the position of extra registers on
>the 6309 during an interrupt, the offset had to change. This affected both
>RUNB and BASIC09 itself.
>    Some other programs (Home Publisher is one) also needed patches for
>similiar reasons. Others (like Flight Sim II) were patched for 6309
>versions so that they would run more efficiently. Basically, any program
>that installed it's own SWI calls would need patching, unless it only used
>the registers that didn't move (like CC) in the new IRQ stack frame.

Aha!  So this is the other reason we had to patch things like os9p4.  I had 
forgotten about those programs that may have popped what they thought was the 
return address off the stack and found themselves at the funny farm when they 
did.  Almost any proggy compiled by the microware c compiler could be 
foobared by that, as that was one of its favorite save 2 bytes and an 
instruction fetch tricks.  I even used it myself a few times.

-- 
Cheers, Gene
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