From: "Charles Sandmann" Newsgroups: comp.os.msdos.djgpp Subject: Re: "Committed" Pages Date: Tue, 19 Sep 2000 13:17:10 Organization: Aspen Technology, Inc. Lines: 16 Message-ID: <39c76756.sandmann@clio.rice.edu> References: <39C76576 DOT C53659B4 AT freemm DOT org> NNTP-Posting-Host: dcloan.hou.aspentech.com X-Trace: selma.aspentech.com 969387823 7102 10.32.115.107 (19 Sep 2000 18:23:43 GMT) X-Complaints-To: postmaster AT aspentech DOT com NNTP-Posting-Date: 19 Sep 2000 18:23:43 GMT X-NewsEditor: ED-1.5.8 To: djgpp AT delorie DOT com DJ-Gateway: from newsgroup comp.os.msdos.djgpp Reply-To: djgpp AT delorie DOT com > 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.