I assume you mean "When was the first operating system introduced?" Seems to be in the 1950s. See the link below for a very detailed page.
Windows 95 OSR2
(Q)-Wireless Zero Configuration was first introduced with which operating system? (A)-Windows XP
Windows Server 2008
Microsoft's first operating system named Windows was introduced on November 20, 1985. The Microsoft Windows operating system is now available in 137 languages.
Windows 2000
Apple made first use of the sidebar in its computing operating system called "Mac OS". The original version of this operating system was introduced in 1984 and was termed "System".
macintosh
DOS {disk operating system }
As of 2011 the newest Operating System was OSx 10.7 Lion, introduced July 20, 2011.
Active Directory was previewed in 1999, released first with Windows 2000 Server edition
XP is a complete operating system, not simply an operating environment.
Any modern operating system, windows xp/vista/7, linux, osx etc. Fat 32 was first introduced in windows 95