Sorry guys, it came earlier than that. VAX/VMS had exactly the same kind
of split and the architect of VMS also designed the NT kernel.
The 4GB is 4GB simply because that's the addressing range you get from 32
bits. So a flat address space on a 32-bit processor is inherently 4GB
wide.
VMS and then NT split the process address space in half, and gave half to
the private process space and the other half to shared system space.
Making it a 50-50 split is just one of those broad-brush simplifications
that you make if you want to avoid any hint of segments.
A flat address space just _had_ to be unbearably attractive to Microsoft
after all the hassle they had been through during the growth from 8086 to
80386.
mike@efikim.compulink.co.uk (Mike Finley) wrote:
> I don't think there is an alpha port, no. The split comes originally
> from
> the MIPS version of NT though, not Alpha.
>
> mike
>
> -----Original Message-----
> From: owner-filmscanners@halftone.co.uk
> [mailto:owner-filmscanners@halftone.co.uk]On Behalf Of Mark Edmonds
> Sent: 09 March 2001 20:13
> To: filmscanners@halftone.co.uk
> Subject: Re: filmscanners: RE: Win2k and application RAM
>
>
> I can confirm the 2GB split between OS and App RAM. It is something to
> do with the Alpha port of NT I think and to keep things consistent for
> the coders, Microsoft translated the Alpha restriction to the Pentium
> version. I believe W2K has the same problem but I don't think there is
> an Alpha port of W2K - can this be confirmed?
>
> Mark
>
> In message <EJEKINMEKEDPJJMHLODJCEFACIAA.marshalt@spiritone.com>, Frank
> Paris <marshalt@spiritone.com> writes
> >Well, that's not how it does its memory management.
> >
> >Frank Paris
> >marshalt@spiritone.com
> >
> >
> >> -----Original Message-----
> >> From: owner-filmscanners@halftone.co.uk
> >> [mailto:owner-filmscanners@halftone.co.uk]On Behalf Of Rob Geraghty
> >> Sent: Tuesday, March 06, 2001 2:40 PM
> >> To: filmscanners@halftone.co.uk
> >> Subject: RE: filmscanners: RE: Win2k and application RAM
> >>
> >>
> >> AFAIK the maximum addressable space is 4GB regardless of
> >> the combination of RAM/Virtual. I seriously doubt
> >> that the OS would eat anything like 1 or 2 GB since
> >> Win2K runs happily in 128MB, so that would leave most
> >> of the 4GB available to applications.
> >
> >> Rob
>
>
