China DOS Union

To All：

The day before yesterday I read quite a few DOS posts and ran into many concepts that seem right and yet not quite right, and now I'm a bit confused.

Pure DOS (pure DOS): does only DOS below version 6.22 count as pure DOS? I think these two concepts are different.

Real DOS (real DOS): I think this concept didn't exist before Win95 was released, so what does it refer to? Does it mean the DOS 7.x that comes with Win9x, or the command prompt mode you choose at boot?

What surprises me even more is that in many posts real and pure are treated as completely the same thing. I'd like to ask all the experts, please don't hesitate to enlighten me so as to set the record straight. Thanks!

The concepts of “real” DOS and “pure” DOS are completely different.

So-called “real DOS” means DOS in 16-bit real mode. That is to say, as long as you do not load some 32-bit protected-mode drivers (such as EMM386, CWSDPMI, and various VCPI, DPMI, DPMS drivers), then it is “real-mode DOS,” as distinguished from “protected-mode DOS” or “V86 virtual-mode DOS.” This concept existed long ago, not only after Win95 was released.

So-called “pure DOS” is actually a very abstract concept. But what is usually meant by “pure DOS” is DOS when the Win3.x/9x GUI is not running, for example pure MS-DOS 7.10, pure ROM-DOS 7.10, pure FreeDOS, etc., rather than something distinguished by DOS version number (for example, the claim that “only DOS below 6.22 counts as pure DOS” is complete nonsense). For example, although RxDOS 6.2 is not very compatible, it is still “pure DOS,” not to mention very compatible ones like MS-DOS 7.1 and PC-DOS 7.1.

Then under Win9x, if right after booting you first press F8 to enter the startup menu, then press Ctrl+F5 to enter DOS, without loading any TSR programs or drivers, would DOS like that be called real DOS mode or pure DOS?

It should be Real-Mode, right

But if you load a UMB driver like EMM386, then it's protected mode

But UMBPCI is real mode

In that situation, if there is no EMM386, then it is both “pure DOS” and “real DOS.” If EMM386 is loaded, then it is only “pure DOS,” not “real DOS.” If you use WIN and enter WIN, then it is neither “pure DOS” nor “real DOS” (though at that time you are still under “impure” DOS, because WIN is only a GUI). Also, basically speaking, if you are under “real DOS,” then you are also under “pure DOS” (but not the other way around)..

Once you understand this question, it's actually very simple.

Completely confused

Then what differences are there between “pure DOS” and “real DOS” in actual use and in functionality?
I often see some software operations requiring that they be done under “pure DOS.” For example, when flashing the BOIS, some boot disks just won't work.

The following is a quote from E140 on 2003-9-16 23:01:29:
Then what differences are there between “pure DOS” and “real DOS” in actual use and in functionality?
I often see some software operations requiring that they be done under "“pure DOS”. For example, when flashing the BOIS, some boot disks just won't work.

That's a typical case of mixing up the concepts. BIOS flashing should be done under “real-mode DOS,” but not necessarily under “pure DOS”; for example, if EMM386 is loaded, then it won't work.

Bump, now it's clear!