WarGreymon77 wrote on 2020-09-26, 07:44:

I can't see any reason why a DOS program wouldn't work in Windows 98 just fine, though.

Oh, there's plenty of reasons.

It's got plenty of compatibility thingies and virtual machines built into the OS, if I recall.

There's just one virtual machine, designed to run on the hardware from 90s, which inevitably led to severe limitations.
Decent virtual machines - like Dosbox - came much later.

WarGreymon77 wrote on 2020-09-26, 07:44:

I can't see any reason why a DOS program wouldn't work in Windows 98 just fine, though. It's got plenty of compatibility thingies and virtual machines built into the OS, if I recall.

Perhaps you are thinking of "How to ensure that your program does not run under Windows 95", the bonus chapter from Raymond Chen's book?
http://ptgmedia.pearsoncmg.com/images/9780321 … _bonus_ch02.pdf

It seems they did a very meticulous job of tracking down a lot of badly-programmed software, but it's unthinkable that they could have covered every possible case.

WarGreymon77 wrote on 2020-09-26, 07:44:

I can't see any reason why a DOS program wouldn't work in Windows 98 just fine, though.

I believe Windows 98 DOS VMs have about the same limitations like DOS+EMM386 in V86 mode.
Accesses to the bare metal are either prohibited, intercepted or delayed (-> timing issues).
And I assume, some DOS programs just don't like this. 🙁

Grzyb wrote on 2020-09-26, 10:41:

It's got plenty of compatibility thingies and virtual machines built into the OS, if I recall.

There's just one virtual machine, designed to run on the hardware from 90s, which inevitably led to severe limitations.
Decent virtual machines - like Dosbox - came much later.

I think there's a x86 port of Virtual PC 4 for Windows 98 and OS/2, but yes, VMs generally came by the end of the 90s, I think. Emulators like SoftAT, SoftPC (used by NTVDM on RISC), SoftWindows and Virtual PC (Mac) existed earlier. Almost-VMs like dosemu or Wabi excluded. 😉

Jo22 wrote on 2020-09-26, 17:35:

I believe Windows 98 DOS VMs have about the same limitations like DOS+EMM386 in V86 mode.

There's more limitations.
VDMs under Windows work with multitasking, which causes various timing problems, eg. it's not allowed to change the timer interrupt frequency.