We say an environment is heterogenous when it contains diverse families. In computer-related terminology, it is used to describe a computing environment in which various operating systems are used cooperatively, such that data from one system is passed to another. This can be as simple as sharing files on physical media, but usually applies to the participation of several disparate computers on the same network.
Numerous software packages have been designed to foster interoperability in heterogenous networking environments. Perhaps the most famous is samba, a system for providing Microsoft SMB/NetBIOS networking over TCP/IP. Only slightly less well-known is netatalk, which provides Apple's AppleTalk networking over the AppleTalk DDP protocol or TCP/IP. A package for the MacOS called Dave provides NetBIOS client capabilities. Windows NT comes equipped to speak with both Novell and Macintosh/AppleTalk servers and clients.
Even Unix shell users can experience problems in environments with varied Unix variants, as termcap/terminfo settings often vary between vendors.