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> > I'm not arguing about convention, here.
>
>     Brendan:
>
>     I admire your independent thinking; it's nice to see someone
>     discarding the usual assumptions and starting over from
>     more-or-less basic principles.

Thanks :)

>     It's useful to keep in mind, though, that when you see a design
>     feature common to nearly all microcontrollers, it probably
> exists
>     for reasons other than arbitrary "convention".

Respecting your professional opinion, I should point out that that is
not always the case.  Witness the convention across the
microcontroller board of using register or acumulator oriented
operations where a stack would be far more effective.  Now, of
course, the reason for that is that it's easier for programmers to
understand, but at the same time, your system takes a performance hit
for staying in the game that way.

> > I hope you can see that there are other functional schemes that
> > could use a full RAM clear in the reset process.  I don't think
> > there'd be much loss there, but there might be very little gain.
> > I'll leave that analysis to the professional chip designers.
>
>     As a professional chip designer, I agree that a full RAM clear
>     IS generally needed on reset.  However, I don't think it should
>     automatically be performed by the hardware.

Perhaps, then, a RAMCLR instruction which will dump all the RAM on
the processor?  Or all of it except for a protected zone?

>     I mean, even the 18F's RAM can be cleared in fewer than 12
>     software instructions.  Even if the micro cleared all RAM
>     automatically on reset, that 12-instruction routine would
>     probably be in most programs anyway, in order to clear RAM when
>     necessary under other circumstances (e.g., WDT reset).

Fair enough, though I haven't been able to figure out why a routine
like this would be implemented in the first place.  It sounds to me
like exactly the kind of coding practice that we are commonly advised
to avoid: why do you need to clear all the RAM, when you should be
assuming that it's all full of garbage anyways?

Well, now that I think about it, I can see some potential uses, like
a large data array that needs to be full of 0s, but in general, I
can't really see the need for something like that at all...

- --Brendan
- ---
"Rejection out of hand of all but one's favoured alternative may cost
you dearly in one way or another." -Russell McMahon

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