3+Share

[1][2] In 1984, Microsoft announced MS-Net, a framework for building multitasking network servers that ran on top of single-tasking MS-DOS.

MS-Net implemented only the basic services for file and print sharing, and left out the actual networking protocol stack in favor of a virtual system in the form of IBM's NetBIOS.

XNS provided the networking protocol as well as connections to the underlying Ethernet hardware it ran on, which Metcalfe had also helped design.

Internally, 3+Share had a network stack, file and print server modules, disk caching, user handling and more, all running simultaneously inside the DOS memory space.

3Com soon lost interest in the network software market, handing over its LAN Manager product (now called 3+Open) as well as its intellectual property to Microsoft in 1991.