# Macintosh RS-422

It's possible to connect RS-232 peripheral to the RS-422 port available on Macintosh computers. Use RXD- as RXD, TXD- as TXD, Ground RXD+, Leave TXD+ unconnected, GPi as CD.

(at the computer)

8 PIN MINI-DIN FEMALE at the computer.

Pin | Name | Dir | Description
--- | --- | --- | ---
1 | HSKo |  | Output Handshake
2 | HSKi/CLK |  | Input Handshake or External Clock
3 | TXD- |  | Transmit Data (-)
4 | GND |  | Ground
5 | RXD- |  | Receive Data (-)
6 | TXD+ |  | Transmit Data (+)
7 | GPi |  | General Purpose Input
8 | RXD+ |  | Receive Data (+)

Note: Direction is DTE (Computer) relative DCE (Modem).

Note: GPi is connected to SCC Data Carrier Detect (or to Receive/Transmit Clock if the VIA1 SYNC signal is high). Not connected on the Macintosh Plus, Classic, Classic II, LC, LC II or IIsi.

Contributor: Joakim Ögren, Pierre Olivier, Ben Harris, Nathan Schmidt

Source:
comp.sys.mac.comm FAQ Part 1, Apple Tech Info Library, Article ID: TECHINFO-0001699

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Document last modified: 2001-06-08