From: "Colin W. Glenn" Newsgroups: comp.os.msdos.djgpp Subject: Re: Displaying volumename in prompt Date: Thu, 26 Dec 1996 19:26:29 -0600 Organization: Greater New Orleans Free-Net Lines: 41 Message-ID: References: <5974bk$j7e$2 AT tornix DOT tornado DOT be> <19961225 DOT 134311 DOT 4743 DOT 2 DOT chambersb AT juno DOT com> NNTP-Posting-Host: sparkie.gnofn.org Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII In-Reply-To: <19961225.134311.4743.2.chambersb@juno.com> To: djgpp AT delorie DOT com DJ-Gateway: from newsgroup comp.os.msdos.djgpp > >Actually, I wouldn't mind a MSDOS equivalment of MSDOS. I mean, with > >machines we have now, you could convince the system to fold every bit > >memory under the 1meg mark. That means that every application would > >able to load and run, one on top of the other. > Two questions: > 1) An MSDOS version of MSDOS? Ok, ok, bad wording. What I mean is a operating system which would allow current programs written for the MSDOS to work, while...>> > 2) Would this be with unlimited segments or something? How else > would it 'fold'? Allowing more programs to run within the 640k space allowed for under the current version of MSDOS. Yes, 'unlimited segments'. I've just browsed the setup on using GDTs and LDTs, so I may stumble here or there but lets see if I can make this sound right. Under PM, a segment register becomes a pointer to a table which the processor uses to access the 'real' address of the memory block in question, the OS has the GDT setup, and configures a LDT for every process which it runs. The only programs which would not run under this mode would be programs which 'increment' an index register because this would cause a processor excemption fault. And there might be a cure for that as well, the interrupt handler would simply create a new LDT for a segment which would exist 16 bytes beyond the start of the segment the program had incremented, load that into the registar and 'RESUME NEXT'. Of course this should involve the user, ie let him/her know that: PROGRAM such-and-such just violated segment integrity, [C]orrect fault or [A]bort process? This fault correction could also be incorparated into some type of table which would bypass this prompt, ie the system knows ahead of time that this program will cause a fault. Such an OS would also be able to handle WIN programs without invoking Windows, it just develops the resources the programf needs without the user every having to know whether it's a windows program or not. Hmmm, tall order. Might have to void the window service on the beta test.