Comment by lloydatkinson
11 hours ago
> Sadly, Windows 11 can’t run 16-bit Windows programs by itself, because 64-bit Windows has no NTVDM, so we’re going to have to find something from the early NT era.
I remember a recent-ish post on here that really, I mean really, dived deep into this whole thing. It turns out that it was mostly a lack of willpower or maybe political that stopped Windows 64bit running 16 bit apps.
Somewhere in the kernel, with some obscure mechanism there is support for some kind of emulation that if implemented would allow it to run NTVDM and therefore these 16 bit apps.
The author of the post even had some kind of proof of concept of running a 16 bit DOS app directly under Windows 64 bit with this.
The details are blurry, but I believe that that had the Windows team really wanted to this emulation could have been built in and totally seamless.
I got the impression that this was actually a fairly new finding which is why I suppose no one has tried it.
https://felsqualle.com/posts/2022/12/16-bit-support-in-64-bi... is the full story.
but tl;dr is that ntvdm relied on the CPU running 16-bit code, so was naturally EOL on a 64-bit Windows, where that mode doesn't work.
winvdm adds it back via CPU emulation.
I remember the post I read being a black themed site but this is also interesting, thanks