There is a lot of magic and hard-core engineering work on Microsoft's part to that. Windows/386 is an hypervisor that runs the Windows as one of the VMs, origi

There is a lot of magic and hard-core engineering work on Microsoft's part to that. Windows/386 is an hypervisor that runs the Windows as one of the VMs, original DOS as another and can create additional DOS VMs. Windows 3.1 then added the capability of this hypervisor to run some limited kinds of native i386 Windows NT applications on their own VMs that can do inter-VM IPC. Windows 95 extended this architecture to the extreme, there was no “Windows in a VM”, Windows was the OS, that ran Win32 API processes directly, traditional 16bit applications also mostly directly and mainly: it managed bunch VM86 VMs. Prime VM of these ran the original DOS with all of its drivers, which was then used for hardware that did not have native Windows drivers. Another VMs contained the DOS software that you ran. The whole thing was somehow capable of translating the API calls from not only 3 different client ABIs, but also to 3 different driver ABIs…