MFJ-1270C/1274C COMPUTER INTERFACING
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section on Other Computers with 25-pin RS-232C Ports. Otherwise refer to the
section Other Computers with Nonstandard Serial Ports.
Some computers have no serial port and no adapter is commercially available.
Such computers are not suitable for use with the MFJ TNC.
Computers with Specific Serial Interfaces
Apple Macintosh
The Macintosh serial port is an RS-422 compatible port, but it will work fine
with the RS-232C serial port on your MFJ TNC .
MFJ Enterprises, Inc. offers an optional Starter Pack for the Macintosh. It can be
purchased from MFJ Enterprises, Inc. or any MFJ dealer. The Starter Pack
includes an interface cable for connecting the MFJ TNC to the Macintosh and a
terminal program. The Starter Pack for Macintosh is MFJ-1287. If you wish to
use your own cable, you will need a cable wired as shown in Fig. 2-1.
Macintosh MFJ TNC Macintosh MFJ TNC
8 pin DB-25P DB-9P DB-25P
1 (HSKO) 4 1 1
2 (HSKI) 5 5 2
3 (TXD-) 2 9 3
4 (GND) 7 3 7
5 (RXD-) 3 7 8
6 (TXD+) N/C 6 4
7 (GPi) 8
8 (RXD+) 7
Shield 1
Macintosh To MFJ TNC Cable Wiring
Fig. 2-1. Serial port wiring for Apple Macintosh.
Note that pin 1 of the DP-9P connector is not connected inside the Macintosh or
the MFJ TNC . If you use a shielded serial cable, which we recommend, connect
both pin 1s to the shield and connect pin 1 of the MFJ TNC serial connector to
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