Windows 7 had that "XP Mode" feature where it would try to run things in a VM, but it was an unloved stepchild. Really, they could have done a lot better-- a V

Windows 7 had that "XP Mode" feature where it would try to run things in a VM, but it was an unloved stepchild. Really, they could have done a lot better-- a VM jukebox with everything from DOS 3.3 onwards available could have made the "most compatible Windows ever"-- even old software that assumed a 4.77MHz CPU clock could have been rigged to run natively.