[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [f-cpu] Register Bank



Juergen Goeritz wrote:
> 
> On Fri, 3 Aug 2001, Ben Franchuk wrote:
> 
> > Juergen Goeritz wrote:
> > >
> > > On Fri, 3 Aug 2001, Ben Franchuk wrote:
> > >
> > > > Juergen Goeritz wrote:
> > > > > Depends on how long you can wait after reset. Some registers,
> > > > > e.g. of the internal pipeline statemachines have to be reset
> > > > > anyway. If you use 256 registers in some inplementation you
> > > > > would wait 256 clocks before the built-in selftest r
> > > > outines
> > > > > can start or you make the reset a part of these. :-)
> > > > Reset pulse is over kill often on length like 1/100 of second.
> > > > You may want to have two resets -- hard reset like power on.
> > > > and warm reset like ctl Alt Del.
> > >
> > > There is no warm reset in hardware! That's just software type.
> > >
> >
> > A warm reset would be similar to a non-mask-able reset.
> > Ben.
> 
> Non maskable interrupt! Definitely not a reset. At least
> I don't know of any processor having two resets :-)
> The NMI usually is used for very high speed reaction on
> external events that must be reacted on. Therefore it is
> not maskable. But it's just another interrupt still.

The whole idea behind two resets deals with the complexity
of the system. I was thinking reset #1 - hard reset - resets the
entire system and cpu's. A second reset would be like a NMI
but just clears only a few specific internal locations to put it into a
known state  for a single thread with bad or damaged code segment.
If you have a cpu controlling a rocket in space - three redundant cpu's
and one goes down from radiation you would just want to reset the one cpu
and still have the other two continue running. You don't want to reset
all 3 and crash the rocket!. Ben. 

-- 
Standard Disclaimer : 97% speculation 2% bad grammar 1% facts.
"Pre-historic Cpu's" http://www.jetnet.ab.ca/users/bfranchuk
Now with schematics.
*************************************************************
To unsubscribe, send an e-mail to majordomo@seul.org with
unsubscribe f-cpu       in the body. http://f-cpu.seul.org/