- Atari ST
- IBM PC 5150/5160
- Mac Plus - Emulates Macintosh 128K, 512K, 512Ke, Mac Plus, Mac SE or Mac Classic
- rc759 Regnecentralen RC759 Piccoline, which I guess was a computer made in/for Denmark specifically
This one is specifically an IBM PC 5150 emulator. Has several disk images, mainly DOS but there's a Windows 1.0 too.
Internet Archive DOS and Windows games
Windows 3.11 in your browser https://archive.org/details/win3_stock
Here's the thing that blows my mind. I ran Windows 3.1 on a 486sx 20Mhz in the early 90s, so about 23-24 years ago. Now it's in my browser and it's not even slow.
This Em-DOSBox generally has a better interface than the other x86 emulators above.
Windows 95 in your browser https://win95.ajf.me/
I'm not sure about the legality of this one. From all accounts it is buggy and tends to hang. I'm sure the Internet Archive version of Windows 3.11 above is legal. For one thing, they don't let you download it. All you can do is stream it from their website.
It's conceivable that someone could make an adventure game set in the 90s with fully working emulated computers from the era, given that all of this stuff works in the average browser these days. Even better if they can simulate a modem and let you dial up to a virtual BBS. It'd be great if Microsoft came out and said that MSDOS and old versions of Windows, such as 3.1 and 95, would be freely available for this sort of thing. After all, "It's a new Microsoft."