On Mon, 25 Aug 1997, John P. Wittkoski wrote:

> Colin Wood wrote:
> 
> > Hmmm...yeah, I seem to remember someone else saying this at some point.
> > There must be some low memory global that we don't quite have the right
> > address for on the IIcx which we are touching.  The only problem with that
> > idea is that I thought a reboot pretty much wiped everything in memory,
> > but I guess maybe it doesn't.
> 
> How does MacOS determine a cold vs. warm startup?

Well, there's a longword called WarmStart (located at low-memory global
location 0x0CFC) that is looked at by (at least) the Slot Manager.  From
my admittedly low level of understanding of this code, WarmStart contains
a value of 0x574C5343 (or, 'WLSC' in ASCII) to signal a restart.  I
haven't a clue as to what the MacOS does differently between the Warm and
Cold starts.  But I'm pretty sure NetBSD/Mac68k doesn't do anything to set
this variable...

> Maybe on reboot MacOS looks for a particular number at a particular
> memory location to determine this. If this is the case, maybe we
> should zap ALL of low level memory right before we "reboot". This
> would cause MacOS to ignore all low level globals and re-create them,
> as it would assume a cold boot.

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