The first commercially available computer system that used a windows based OS was the Xerox Star (1981) this influenced Apple's development of their own Lisa (1983) and Macintosh (1984) windows based systems, a system called GEM created by Digital Research (1985) and Microsoft's Windows (1985).
Microsoft 95 was the first operating system by Microsoft
microsoft disk operating system
Bill Gates was the man who invented Microsoft
I believe the first was MS-DOS or Microsoft Disk Operating System.
Microsoft
Microsoft's first operating system named Windows was introduced on November 20, 1985. The Microsoft Windows operating system is now available in 137 languages.
MicroSoft - Disk Operating System
Windows 95 was the "first Microsoft Windows operating system" released on August 24, 1995. The "first Microsoft Operating system" was DOS 1.0. Windows 1.0 up to 3.1 were all operating environments. That is software that acts as an operating system, but need an operating system to boot in this case DOS. The answer to your very specific question is Window 95 that was released on August 24, 1995.P.S. Windows 95 was also the first Windows to utilize Plug and Play. (PnP)
Microsoft
No. You need an operating system to do the installing.
Not at all. The first graphical operating system was on the Xerox Alto workstation.
Windows 7 is the name of new Microsoft's operating system.