uses of RS-422 was on the early Macintosh computers. This was implemented in a multi-pin connector that had enough pins to support the majority of the common RS-232 pins; the first models used a 9-pin D connector, but this was quickly replaced by a mini-DIN-8 connector. The ports could be put into either RS-232 or RS-422 mode, which changes the behavior of some of the pins while turning others on or off completely. These connectors are used to support RS-232 devices like modems, AppleTalk networking, RS-422 printers, and other peripherals. Two such ports were part of early Apple Macintosh series designs until they were replaced, along with ADB ports, by Universal Serial Bus on the iMac in 1998. RS-422 is a common transport mechanism for RS-232 extenders. These consist of RS-232 ports on either end of an RS-422 connection. Before hard-disk-based playout and editing systems were used, broadcast automation systems and post-production linear editing facilities used RS-422A to remotely control the players/recorders located in the central apparatus room. In most cases the Sony 9-pin connection was used, which makes use of a DE-9 connector. This is the de facto industry standard connector for RS-422, which is still found on broadcast equipment today. See also Differential TTL Electronic Industries Alliance Fieldbus List of network buses Profibus References Further reading EIA standards Serial buses Serial communication interfaces