PATHHardware Documentation > USB Devices > Mac OS USB DDK API Reference

Macintosh-To-Macintosh USB Connections

USB is a serial communications channel, but does not replace LocalTalk functionality on Macintosh computers. You cannot connect two Macintosh computers together using the USB like you can in a LocalTalk serial network for a couple of reasons.

• The USB cable connectors are designed in such a way that it should be impossible to attach two upstream devices together. A standard USB cable has one upstream connector and one downstream connector. The root hub in the Macintosh computer is the first device on the USB, and as such it is always an upstream device in the USB topology.
• The USB uses a master/slave communication model in which the Macintosh host controls all communication and is the master of the bus. There cannot be two masters on the same bus.

The most cost efficient method for networking USB enabled Macintosh computers together is through the built-in Ethernet port.

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