Mac serial cables use all 8 pins; However, Three pair are swapped.

Pin Postitions

1 2

3 4 5

6 7 8

Terry Lee looked on apples web page and found this:

-----------------------------
Pin RS-422 name RS-232 equivalent
1 HSKo (handshake out) DTR (data terminal ready)
2 HSKi (handshake in) CTS (clear to send)
3 TXD- (transmit data negative) TXD (transmit data)
4 GND (signal ground) GND (signal ground)
5 RXD- (receive data negative) RXD (receive data)
6 TXD+ (transmit data positive) leave unconnected
7 not connected not connected
8 RXD+ (receive data positive) must be grounded to pin 4
(on Macintosh RS-422
connector)


Cable pinout by Mark Phillips
1 ------------------- 2
2 ------------------- 1
3 ------------------- 5
4 GND 4
5 ------------------- 3
6 ------------------- 8
7 not used 7 connecting a wire here does no harm
8 ------------------- 6