TOPS, an acronym for transparent operating system, is a type of local-area network designed by Sun Microsystems that can combine Apple Macintosh computers, PCs, and Sun workstations on the same network. A particular strength of TOPS is that the networking software is transparent, meaning that users do not need to adjust to a new operating environment. PC users see their PC interface and Mac users see the Mac interface.
TOPS uses the Macintosh computer’s built-in AppleTalk protocol. It is a peer-to-peer network, which means that it does not require any computers to be set aside as file servers. Authorized users can access files from any disk drive connected to the network.