I wouldn't call it "virtual DOS". Windows NT/2K/XP had a "virtual DOS"; 9x and ME had, well, MS-DOS sessions.

It doesn't exactly answer your question, but Raymond Chen wrote about some of the heroic efforts that were made to ensure buggy MS-DOS games would play happily with Windows.
http://ptgmedia.pearsoncmg.com/images/9780321 … _bonus_ch02.pdf

Looks like he's still been writing about it on his blog lately:
https://blogs.msdn.microsoft.com/oldnewthing/ … 328-00/?p=93204
https://blogs.msdn.microsoft.com/oldnewthing/ … 425-00/?p=93345
https://blogs.msdn.microsoft.com/oldnewthing/ … 418-00/?p=93307

Ultima 7 often comes up as a game that doesn't play well with Win9x, but then there's U7Run, which is specifically intended to get Ultima 7 running in such cases. There's almost certainly something out there that abuses the hardware in unexpected ways that are incompatible with WIn9x, but offhand I can't recall what they are.

Anything that really abuses the PC speaker is a good start, like Links.

Same level as DOS+EMM386, I'd say. EMM386 is basically a minimalistic OS, encapsulating DOS.
And both are virtual in some kind. For true DOS, get an EMS card, use hardware UMBs and stay in real-mode.

Jo22 wrote:

For true DOS, get an EMS card, use hardware UMBs and stay in real-mode.

Any software author that wrote programs exclusively for those with an EMS card would have severely restricted his or her audience.

I remember Fast Tracker 2 would refuse to run on Windows' VDM, its demand pure DOS with memory manager that support VCPI or DPMI (or i just use emulator like DosBox).

Jorpho wrote:

Jo22 wrote:

For true DOS, get an EMS card, use hardware UMBs and stay in real-mode.

Any software author that wrote programs exclusively for those with an EMS card would have severely restricted his or her audience.

They didn't have to. But for some reason they decided to restrict their audiences later on.
It was about '93, I think, when those DOS4GW based apps did creep out of their coffins. 😉
The irony is, up to this point featurerich 286 machines (some with EMS, btw) just became common and affordable.

Edit: Thank you very much for the links to Mr. Chen's blog! I've just read a few pages, but it's already beyond awesome.
Just love that sarcastic undertone in his writing! 😀

leileilol wrote:

Anything that really abuses the PC speaker is a good start, like Links.

Time for magical mushrooms, yay ! *link*

I had the opposite problem : Terminal Velocity would freeze in DOS if sound was enabled. It had to run under 9x DOS. My sound card was a jazz 16 media vision. There was a DOS driver that made it sound blaster ish. It mostly worked. Mostly. But not for TV 🙁

I don't know how they did it, but the win 9x DOS sound blaster emulation seemed to just always work.