Robin Williams Mac OS X Book, Jaguar Edition, The

Serial Ports

Printer and external modem ports

A serial port is the little round one that looks similar to the ADB port, but it has more holes (to match the pins on the connector). There are two data wires in a serial cable, so the port can send and receive information at the same time.

There are usually two serial ports on the back of older Macs—one labeled with a little picture of a printer, and the other with a picture of a telephone. Although you can use either port for either a printer or an external modem cable, the printer port is actually slightly different in that it is the Mac’s LocalTalk network port. This just means it’s faster and more complex than the modem port, and if possible you should plug your serial printer cable into that ...