Subject: Re: signal(SIGSEGV, SIG_IGN) -> 100% CPU
To: der Mouse <mouse@Rodents.Montreal.QC.CA>
From: Paul B Dokas <>
List: tech-kern
Date: 06/12/1999 10:04:14
On Sat, 12 Jun 1999, der Mouse wrote:
> > You remember correctly about /bin/sh.  This was especially amusing to
> > the people porting v7 UNIX to the mc68000, which didn't keep enough
> > state to restart the faulting instruction...
> I seem to recall hearing of some machine that had two 68ks in it, one
> running one instruction behind the other.  When the active one took a
> trap, the other one was frozen, one instruction behind, so it could
> become the active one and thus "restart" the faulting instruction.
> I can see all sorts of problems with such a scheme, but if the machine
> ever worked, someone clearly found solutions....

Yes, old Apollo computers were built with a similar architecture.  It
was the DN3XX's I think.  The ones that were the size of a small
refridgerator.  The University of Michigan had a bunch of these when I was
an undergrad.  They were *really* slow, even for then (ahhh, the good old
days ;-)

Paul Dokas                                  
Don Juan Matus:  "an enigma wrapped in mystery wrapped in a tortilla."