AppleTalk

AppleTalk is a network protocol from Apple Computer. It originally ran over the serial printer ports of Macintosh computers but an Ethernet version called EtherTalk was later introduced and the old serial version came to be known as LocalTalk.

AppleTalk has a higher level protocol called the Printer Access Protocol (PAP) which is a bidirectional protocol for communication with printers. PPR has an interface program called "atalk" which can send jobs to printers using this protocol.