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Article #149Re: VAX question
From: Dileep Bhandarkar
Date: Mon, 27 Jul 1992 09:40
Date: Mon, 27 Jul 1992 09:40
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In article <1992Jul26.015003.1@matrix.cs.wright.edu>, dwagoner@matrix.cs.wright.edu writes... > > >Can anyone explain the difference between P0 and P1 space on a VAX? >Text and initialized data segments (on BSD 4.3, at least) wind up >in P0 space; unitialized data (i.e. stack) is placed in P1 space. >The two regions are accessed using different base registers; P1 is >a bit tricky to work with in comparison to P0. > >Explanations to this ignorant layman are appreciated... > The P0 space begins at virtual address 0 and grows in the direction of larger addresses. P1 starts at virtual address 2**31-1 and grows in the direction of smaller addresses. Since the P1 region grows towards smaller addresses, the base and length registers describe the part of P1 space that is not accessible. Dileep
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arc1-ca.pugleaf.net!sparky!uunet!gatech!destroyer!sol.ctr.columbia.edu!usc!elroy.jpl.nasa.gov!decwrl!deccrl!news.crl.dec.com!rdg.dec.com!ryn.mro4.dec.com!wrksys.enet.dec.com!bhandarkarReferences:
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Newsgroups: comp.sys.dec Path: arc1-ca.pugleaf.net!sparky!uunet!gatech!destroyer!sol.ctr.columbia.edu!usc!elroy.jpl.nasa.gov!decwrl!deccrl!news.crl.dec.com!rdg.dec.com!ryn.mro4.dec.com!wrksys.enet.dec.com!bhandarkar From: bhandarkar@wrksys.enet.dec.com (Dileep Bhandarkar) Subject: Re: VAX question Message-ID: <1992Jul27.134542.4845@ryn.mro4.dec.com> Sender: news@ryn.mro4.dec.com (USENET News System) Organization: Digital Equipment Corporation References: <1992Jul26.015003.1@matrix.cs.wright.edu> Date: 27 JUL 92 09:40:37 Lines: 18