From:	"Charles Sandmann" <sandmann AT clio DOT rice DOT edu>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: "Committed" Pages
Date:	Tue, 19 Sep 2000 13:17:10
Organization:	Aspen Technology, Inc.
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Message-ID:	<39c76756.sandmann@clio.rice.edu>
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> What is the difference between a mapped, unmapped, committed, and
> uncommitted page?

The DPMI 1.0 specification talks about this.  From memory:

 Mapped is a page pointing to a physical device (video frame buffer).
 DPMI 0.9 spec supports address space mapped to devices.

 Committed is a page with a memory space allocated to it.  For example,
 memory you actually reference with a read/write must be committed at
 the time it's used.  You can have a virtual address with nothing 
 behind it - and that will cause a page fault if referenced.  An 
 uncommitted page (like the null pointer page in DJGPP) had address
 space but it's not pointing anywhere.  DPMI 0.9 doesn't support
 uncommitted pages but DPMI 1.0 does.

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