Hi, On Thu, Mar 15, 2012 at 8:23 PM, Eric Auer <e.a...@jpberlin.de> wrote: > >> Thus far, I have been absolutely UNABLE to "break into" a V86 system, > > VCPI is there to share protected mode, not to keep you outside.
http://en.wikipedia.org/wiki/VCPI Yup, developed by PharLap and Quarterdeck, no surprise, as they invented the DOS extender and Desqview, respectively. They were trying to play nice with other protected mode DOS software. > But indeed while you are in V86, you have limitations. Running > your stuff in protected mode with HELP of VCPI would fix this, I'm fairly green here, but I'll try to understand anyways: are you talking about 32-bit segments without overrides? As in slightly faster and no 16-bit segment limits? > but it is annoying to need TWO strategies - while there is no > V86, it is easy to have unlimited access and faster than even > shared protected mode with V86. Again, I don't understand. VCPI for "full" 32-bit and V86 for DOS, isn't that what you're suggesting? >> I must DISAGREE: EMM386 may have been written for "EMS" memory >> but it EVOLVED into Microsoft's protected-mode provider... > > I disagree again - EMM386 got the VCPI extension so Windows and > EMM386 can cooperate instead of being in the way of each other. It was all for Windows originally, even HIMEM, I think. Windows and OS/2 were the future, DOS was old, they thought character-mode only was obsolete long ago. They wanted to mimic the Apple Macintosh (and/or Xerox Star or whatever): GUI, mouse, icon, pointer, overlapping frames. > Raw mode is as good as "VCPI mode" for Windows, because VCPI is > not giving you any fancy services. Can't remember, did Win9x need EMM386 at bootup? I doubt it. Win16 certainly seemed to for "Enhanced" mode, more or less (not counting Win3.0's real mode, which was quickly abandoned). Certainly 2k/XP don't need VCPI (nor DOS) at all, but the guts are probably still the same. > It just gives you a small set > of hooks and levers to share protected mode with EMM386. Under EMM386, you need VCPI to switch to protected mode (if not already enabled). > Windows > can even use the extra GEMMIS interface to clone the whole state > of EMM386 and effectively disable it and do memory management in > both Windows and DOS context itself, so Windows can avoid having > to share responsibilities with EMM386 and can avoid VCPI. Note: > Only very few EMM386 clones implement the low-documented GEMMIS. Yes, Win9x (I think?) had a hidden way of shutting it down so it wouldn't interfere. Quite silly, really. > What I mean: If there is no EMM386, very few apps will "feel bad" > about not having VCPI around. Right, without EMM386 there wouldn't be a need for an official API to switch to pmode and back. > When protected mode is on - be it > EMM386 loaded or Windows running - then the spartan VCPI or the > helpful DPMI are needed by protected mode apps. Windows always considered VCPI inferior for various reasons, hence why it wasn't well-supported except in "standard" (286) mode, barely. You had to use "improved" / "better" DPMI for 386 Enhanced mode (despite Win16 being DPMI 16-bit based, oddly enough). DPMI was invented for Windows, but unlike VCPI, it could be ring 3, better handling of virtual memory, optional 16-bit support, etc. So it was quickly standardized and copied. (Too bad NTVDM is so buggy these days and non-existent on Win64. Also too bad DPMI 1.0 was so rarely utilized.) > DPMI also keeps > you further from hardware - you need less low level code and you > are kept away from it as well. Windows and Linux Dosemu therefore > give you DPMI but not VCPI. The CWSDPMI extender takes raw, VCPI > or DPMI situations as starting point for always giving you DPMI. CWSDPMI won't load at all if DPMI is already found. And it can't load at all if EMM386 is but VCPI isn't found. (And what I was barely referring to before was some rare bugs where some apps and/or extenders didn't handle "NOEMS" correctly because it did or didn't think it also meant "NOVCPI". But, again, that was fairly rare. But it seems a lot of software has such quirks, and DOS is certainly not immune, esp. when most of it is currently not maintained anymore.) ------------------------------------------------------------------------------ This SF email is sponsosred by: Try Windows Azure free for 90 days Click Here http://p.sf.net/sfu/sfd2d-msazure _______________________________________________ Freedos-user mailing list Freedos-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-user
