Presentation Manager (PM) was the name given to the Graphic User Interface (
GUI) which 
IBM introduced in version 1.10 of its operating system 
OS/2 in 1988. 
At the time, IBM and 
Microsoft were collaborating on subsequent version of OS/2; IBM was preparing version 2.0 for the i386 processor, making it the first true 32-bit operating system for personal computers. 
Microsoft began to develop OS/2 3.0 which was intended to be a network server. 
However, during 1990, version 3.0 of 
Windows was beginning to sell, and Microsoft began to loose interest in OS/2. 
The companies parted ways, and IBM took over all of subsequent development.
Microsoft took with it OS/2 3.0, which it renamed Windows NT; as such, it inherited certain characteristics of PM. 
IBM continued to develop PM, but in subsequent versions of OS/2, the name was dropped; there was no distinction made between the operating system and the GUI.
 
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