On Mon, Mar 30, 2015 at 8:37 PM, Rugxulo <rugx...@gmail.com> wrote:
> On Mon, Mar 30, 2015 at 6:59 PM, dmccunney <dennis.mccun...@gmail.com> wrote:
>> Win98 is a protected mode OS, and DOS serves as a real mode
>> loader. Once Win98 is up and running, DOS is out of the loop, and
>> Win98 *is* the OS.
> If DOS is "out of the loop", then why are you still able to run DOS
> files (.COM, .EXE, .BAT)?? Does Windows emulate it? Or is it really
> just calling back to DOS itself? What is responding to the int 21h
> kernel calls?
<sigh> This is OS development 101. Do you think a new OS intended as
a followup to an existing product throws out the baby with the
bathwater and does everything differently, so existing apps won't run?
It includes it. Part of the problem for Windows 9X was maintaining
backwards compatibility. It needed to be able to run old 16 bit DOS
apps as well as apps written for Windows. Batch files were
interpreted by COMMAND.COM, and COMMAND.COM was available. COM and
EXE files were programs run under the OS, and Windows supported the
system calls those programs used. There would be no need to call the
underlying DOS, because the required stuff was part of Win98.
I repeat, DOS was a real mode loader, whose function was to load
Windows. Once it had, Windows took over.
> For something like Windows XP, then definitely DOS isn't there, it's
> emulated in NTVDM. But to pretend that Win98 runs all by itself
> without DOS is a bit of a stretch.
No, it isn't. Win98 needed DOS to load it. That's it. And that
requirement is a consequence of X86 segmented architecture with real
mode and protected mode. The machine started in real mode, and needed
a real mode loader to load the protected mode OS.
NT finally removed that requirement and could be booted without DOS,
but the issues of maintaining backwards compatibility made getting
there a one step at a time process.
> Hasn't this already been discussed to death before? MS was later sued
> (and lost) for illegally bundling their DOS with their Windows. I
I don't recall that, and rather doubt there was anything illegal about
it. MS owned MSDOS and Windows, and could use them and bundle them as
> think Caldera (or Lineo or whatever they were eventually called) even
> legitimately proved that they could boot Win95 atop DR-DOS. Win95 and
> MS-DOS weren't bundled for technical reasons, only marketing reasons.
> It was much closer (technically) to Windows 3.1 than most people
You could indeed boot Windows atop DR-DOS, but why bother? You would
only be likely to do so if you already ran DR-DOS and wanted to run
Windows too. And remember, DR-DOS began because DR had customers
wanted a ROMmable version of DOS for embedded applications. MSDOS at
the time was not architected to provide the required separation
between code and data, and could not be embedded in ROM. Offering
DR-DOS as a consumer product was a later development.
Most folks who got Windows got it as the next step beyond DOS, and
wanted to simply install it and run it. They did not want to first
install a flavor of DOS and then install Windows on top of it.
And then, as now, people generally bought Windows PCs with the OS
already installed by the vendor.
I remember the early days when the PC was first out, and MSDOS/PCDOS,
Digital Research CP/M 86, and the UCSD P-system were all fighting for
a chunk of the PD market. MS won. The others lost. Deal with it.
> I'm not sure why they bothered. Obviously NT had much higher
> requirements back then (mid '90s), e.g. 16 MB minimum (and 80 MB disk
> space?) while Win95 could (very slowly) run atop a 4 MB 386. They
> wouldn't even fix NTVDM bugs for Quake (from id Software, compiled for
> DOS via DJGPP) because "NT wasn't for games"! But that's all lost to
> the sands of time now that XP fully replaced Win9x for "home" users.
> (2000 first added Win9x-era LFNs and FAT32, but even that wasn't yet
> targeted at home users, hence we were only offered Windows ME.)
MS was focused on business users (and still is - Win10 is very much
geared to the Enterprise market ). NT was aimed at the business
desktop. Part of the problem from an OS perspective was that games
for platforms like DOS assumed they were the only program running and
owned the hardware, and would write directly to the hardware to get
performance. That's a no-no in a multitasking OS. It took a while
before MS realized that gaming was market and money could be made in
it, and did things like implement Direct-X to provide OS modulated
access to the hardware that games needed.
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