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: 2002-01-10