The Cypress AN2720SC provides a single-chip solution for networking two or more computers via their USB ports. In a USB system, the PC acts as a host, which initiates all USB traffic. USB devices act as slaves, which respond to host requests. It is inherently incompatible to connect two PCs together via a simple USB cable, since a master (host) cannot talk to another master (host). A master can talk only to one or more slave devices. The AN2720SC overcomes this "peer-to-peer" incompatibility by providing two USB devices, one for each PC. Two independent Serial Interface Engines (SIE) exchange data through a 2 kilobyte FIFO. Thus, USB data transmitted by one computer is made available to the other computer through the AN2720SC. The connection is full duplex data can be transferred in both directions simultaneously.