[Signalman]

Windows 3.1 was not a true operating system (OS) It was an “operating environment” containing a graphical user interface (GUI), which sat on top of DOS, making it easier for the human user to interface with the computer. DOS still performed the underlying functions of the OS.

Windows 95 was the first true non-DOS Microsoft OS.

[dayglored]

> Windows 3.1 was not a true operating system (OS) It was an “operating environment” containing a graphical user interface (GUI), which sat on top of DOS, making it easier for the human user to interface with the computer. DOS still performed the underlying functions of the OS. Windows 95 was the first true non-DOS Microsoft OS.

Not true.

Win95 and Win98 and WinME all required DOS underneath. They hid it better and better, but it was still there.

The NT branch releases -- NT3.x, NT4, NT5/Win2K, NT5.1/WinXP, NT6/Vista, NT6.1/Win7 -- all are independent of DOS.