NetWare for OS/2 was one of the most technically interesting products of the mid-1990s. Novell’s NetWare was long established as a file server for LANs; since NetWare/386, Novell’s NOS ran as a dedicated server which was loaded from DOS but took over the entire system once started. But ever since the late 1980s, Novell was talking about a non-dedicated NetWare server running on top of OS/2.
In August 1993, Novell finally released NetWare for OS/2 as a $200 add-on to NetWare 4.01. With the add-on, NetWare 4.01 server could be installed on top of OS/2. A single OS/2 machine could function as an OS/2 application server, a NetWare server, and could also run the NetWare client at the same time.
NetWare for OS/2 was essentially a paravirtualization layer (even though the term did not yet exist at the time) for NetWare which largely replaced direct hardware access by functionality provided by OS/2. The NetWare server could still use its own network drivers, but disk access and memory management were handled by OS/2, and NetWare ran as a special task. NetWare for OS/2 could run the same NLMs (NetWare Loadable modules) which dedicated NetWare servers supported. Continue reading