Article View: comp.os.msdos.misc
Article #2924Re: Is dos 6.0 gonna multitask? Or have no memory barrier????
From: Alex Oren
Date: Tue, 17 Nov 1992 18:41
Date: Tue, 17 Nov 1992 18:41
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>DOS doesn't have a 640K barrier. DOS will use as much CONTINOUS memory it >can find. Wrong! DOS, as a real-mode-8086 operating system (?) cannot use more than 1MB of memory (ROM, RAM and variations). The 1MB barrier comes from the 8086 architecture. The 640K barrier comes from IBM's design of the PC, where 384K where reserved for the BIOS, video buffer, adapter memory etc. If an OS uses memory schemes which depend on more than 20-bit address space (XMS), require protected-mode (DPMI, VCPI) or special hardware support (EMS) then it cannot run on a plain PC/XT compatible, so it is not "DOS". However, there were computers which implemented the video buffer higher in memory, leaving DOS with more than 640K (though less than 1MB) Arivederci, Alex
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Path: arc1-ca.pugleaf.net!sparky!uunet!news.univie.ac.at!blekul11!frmop11!barilvm!bimacs!orenalex From: orenalex@bimacs.BITNET (Alex Oren) Newsgroups: comp.os.msdos.misc Subject: Re: Is dos 6.0 gonna multitask? Or have no memory barrier???? Message-ID: <4478@bimacs.BITNET> Date: 17 Nov 92 18:41:07 GMT References: <1992Nov10.174211.1@csc.canterbury.ac.nz> <1992Nov10.060504.10390@netcom.com> <BxKoEC.JC8@news.cso.uiuc.edu> Organization: Math department, Bar-Ilan University, Ramat-Gan, ISRAEL Lines: 29