Paul A. Clayton (paaronclayton.delete@this.gmail.com) on March 1, 2013 6:56 pm wrote:
> David Hess (davidwhess.delete@this.gmail.com) on March 1, 2013 1:58 pm wrote:
> [snip]
> > I still live in 8 and 16 bit land. The more I play with ARM the more annoyed
> > I get with it but not only because of the instruction set.
>
> What makes ARM annoying from the perspective one used to developing for 16-bit systems? Are
> the "not only" reasons related to the ecosystem (e.g., implementers not providing microcontroller
> features appropriate to specific uses or long-term supply guarantees) or to ARM, Ltd. (perhaps
> awkward licensing restrictions or aggressive patent litigation??) or something else?
>
> I am curious about the ISA and the "not only" reasons as I was under the impression that the
> Cortex M series was making progress in meeting requirements for 16-bit microcontrollers (at the
> ISA level--code density, bit manipulation, fast interrupts, etc.--and the implementation level--e.g.,
> decent peripheral selection [though perhaps not yet good support for variable voltage??]); but
> I am extremely ignorant in this and would appreciate a little bit of education.

At least with the ARM based microcontrollers I have looked at, because of the way the peripherals and I/O are connected to the ARM core, the I/O performance and latency is several times slower than the clock frequency would indicate.

Maybe the Cortex ones improve the situation.