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.
8 PIN MINI-DIN FEMALE at the computer.
|2||HSKi/CLK||Input Handshake or External Clock|
|3||TXD-||Transmit Data (-)|
|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.
- comp.sys.mac.comm FAQ Part 1
- Apple Tech Info Library, Article ID: TECHINFO-0001699