Source : Free On-Line Dictionary of Computing

OS2
     
         Normally written "{OS/2}".
     
        [{Jargon File}]
     
        (1997-05-02)

OS/2
     
        /O S too/ {IBM} and {Microsoft}'s successor to the {MS-DOS}
        {operating system} for {Intel 80286} and {Intel 80386}-based
        {microprocessors}.  It is proof that they couldn't get it
        right the second time either.  Often called "Half-an-OS".  The
        design was so {baroque}, and the implementation of 1.x so bad,
        that 3 years after introduction you could still count the
        major {application programs} shipping for it on the fingers of
        two hands, in {unary}.  Later versions improved somewhat, and
        informed hackers now rate them superior to {Microsoft
        Windows}, which isn't saying much.  See {second-system
        effect}.
     
        On an {Intel 80386} or better, OS/2 can {multitask} between
        existing {MS-DOS} {applications}.  OS/2 is strong on
        connectivity and the provision of robust {virtual machines}.
        It can support {Microsoft Windows} programs in addition to its
        own {native} applications.  It also supports the {Presentation
        Manager} {graphical user interface}.
     
        {OS/2} supports {hybrid multiprocessing} (HMP), which provides
        some elements of {symmetric multiprocessing} (SMP), using
        add-on IBM software called {MP/2}.  OS/2 SMP was planned for
        release in late 1993.
     
        After OS/2 1.x the {IBM} and {Microsoft} partnership split.
        IBM continued to develop OS/2 2.0, while Microsoft developed
        what was originally intended to be OS/2 3.0 into {Windows NT}.
        In October 1994, IBM released version OS/2 3.0 (known as
        "Warp") but it is only distantly related to {Windows NT}.
        This version raised the limit on RAM from 16MB to 1GB (like
        Windows NT).
     
        IBM introduced networking with "OS/2 Warp Connect", the first
        multi-user version.  OS/2 Warp 4.0 ("Merlin") is a {network
        operating system}.
     
        {(http://www.mit.edu:8001/activities/os2/os2world.html)}.
     
        [Dates?]
     
        [{Jargon File}]
     
        (1995-07-20)