It is standard DOS packet driver emulating Ethernet. It can link more than 2 computers using only one port per computer. ComRing itself doesn't give any user-level functionality eg. disk sharing, file copying, talk etc. Cable ComRing arranges computers in a form of ring. Data is circulating in fixed direction.
Cable simply connects output of one computer to input of next one.
One wire connects grounds. For two computers it is simple null-modem cable. For details look at the documentation from package. Problems To work properly all connected computers have to have ComRing driver working. If one fails whole network will fail.