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MFJ-1278B MULTI-MODE COMPUTER INTERFACING
Many computers require a serial port adapter card. These cards incorporate the circuitry
necessary to add an RS-232C port to the computer. Some popular models in this category are
the Apple II series, the IBM Personal Computer, many Radio Shack computers, and the
Sanyo MBC-55X series. If you have one of these computers with an "add-in" serial port, or
if you have another computer we haven't mentioned, you should skip to one of the sections on
"other computers." If your computer has a 25-pin RS-232C serial port, refer to the 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-1278B.
COMPUTER 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-1278B.
MFJ Enterprises, Inc. offers an optional Starter Pack for the Macintosh. The Macintosh
Starter Pack is available from MFJ Enterprises, Inc. or any dealer of MFJ products. The
Starter Pack includes a cable for
connecting the MFJ-1278B to the Macintosh and a terminal program. The Starter Pack for
Macintosh is MFJ-1287B. If you wish to use your own cable, you will need a cable wired as
shown in Fig. 2-1.
Macintosh
8 Pin
MFJ-1278B
DB-25P
Macintosh
DB-9P
MFJ-1278B
DB-25P
1 (HSKO) 4 1 1
2 (HSKI) 6 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) N/C
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-
1278B. We highly recommend the use of shielded cable, when making interconnections
between the computer and the MFJ
-
1278B. Connect both pin 1 on the Macintosh and pin 1