David Hess (davidwhess.delete@this.gmail.com) on March 1, 2013 7:49 pm wrote:
> 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.
>

ST and NXP Cortex-M3/M4 based uCs look not bad at all.
Stellaris/TI had not bad M3-based offerings either, but decided to EOL them in favor of M4-only lineup, that so far looks less complete.
And there are dozens of smaller companies in M3/M4 camp.