Hi John,
That is a sweet looking board. I need to resist the urge to get one too.
I've got plenty that I didn't even use yet :).

I'm not that well versed in ARM yet, but the errors sound like the
instruction mode
is being switched around for some reason. Maybe we need to ensure somehow
that
it sticks with Thumb? There may also be some issue with interworking, I
haven't quite
wrapped my head around that either. A lot to do still.

Some interesting references
https://stackoverflow.com/questions/28669905/what-is-the-difference-between-the-arm-thumb-and-thumb-2-instruction-encodings
https://developer.arm.com/documentation/dui0203/j/interworking-arm-and-thumb/about-interworking

Best regards,
Martin

On Tue, Jan 13, 2026 at 12:40 AM John Sarabacha <[email protected]>
wrote:

> Hi Martin,
> The Cortex-M7 doesn't like the assembler instructions for arm/words, some
> examples:
> ./words/dup.s:4: Error: Thumb does not support this addressing mode -- `str
> tos,[psp,#-4]!'
> ./words/nip.s:4: Error: instruction not supported in Thumb16 mode -- `adds
> psp,#4'
> ./words/abs.s:4: Error: Thumb does not support conditional execution
> ./words/abs.s:5: Error: incorrect condition in IT block -- `b DO_NEXT
>
> Tried different options for the GCC compiler/assembler without success.
>
> FYI
> John S
>
> On Mon, Jan 12, 2026 at 1:13 PM John Sarabacha <[email protected]>
> wrote:
>
> > Hi Martin,
> > Some information on my Cortex-M7 based target platform, Arduino
> > development environment is being is used
> > https://www.pjrc.com/store/teensy41.html
> >
> > Regards,
> > John S
> >
> > On Mon, Jan 12, 2026 at 12:04 PM John Sarabacha <[email protected]>
> > wrote:
> >
> >> Hi Martin,
> >> I will be trying to host amForth on an arm-m7 (600Mhz) platform which
> was
> >> being evaluated a few years ago. I will be using the same process as I
> used
> >> for CH32X033. Any learning I will pass on, M7 is significantly different
> >> than M4 so by sticking to thumb type instructions there should be some
> >> common issues.
> >>
> >> Regards,
> >> John S
> >>
>
>

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