Why did Windows 95 setup use three operating systems?

Doesn't Windows setup still use some weird minimal version of Windows? I remember having to hack my employers provisioning once to install virtio drivers and I ended up in this "purgatory OS" where I could use DOS commands to add drivers.

It's called "WinPE" or Windows Preinstallation Environment. It's very strange. Tools you really think would work like Powershell are completely absent by default, and when added work in unexpected ways.

Adding drivers is also painful, since it doesn't really support all of the regular windows drivers. To sideload drivers you have to do it twice, once for the install image and once for the winpe image.

*My knowledge of this stuff is about 7 years outdated, so it's possible they've improved it since then... Unlikely but possible.

https://en.wikipedia.org/wiki/Windows_Preinstallation_Enviro...

https://learn.microsoft.com/en-us/windows-hardware/manufactu...

I did a bunch of work with WinPE for Win 7,8, and 10. Customizing the environment for automated deployment was a ton of fun. I really came to appreciate the tooling available in WinPE (and it's eccentricities). It's probably what really paved the way for my transition to Linux.