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MFJ-1278B MULTI-MODE COMPUTER INTERFACING
Radio Shack Color Computer
The Color Computer series (except for the Micro Color Computer) uses a 4-pin DIN-style
connector for its serial port. If you wish to construct your own cable, the information in
Figure 2-2 will be helpful. All necessary parts should be available from Radio Shack dealers.
Color Computer DB-25P
4 2
2 3
3 7
Fig. 2-2. Serial port wiring for Radio Shack
Color Computers
Radio Shack Model 100/102 and NEC 8201Radio Shack Model 100, serial port
interfacingThese computers have built-in standard RS-232C serial ports that are compatible
with the MFJ-1278B. You will need a standard male-to-male RS-232C cable to connect the
computer to the MFJ-1278B.
IBM PC/XT/AT/386/486 and compatibles Computer
"Include other computers with 25-pin RS-232 Ports"If your computer is an IBM or
compatible, you should have a serial port with standard DB-25 or DB-9 pin connector. You
may use a standard IBM serial modem cable with the correct gender on each end of the
cable.
MFJ Enterprises, Inc. offers optional Starter Pack (MFJ- 1289) for the IBM or compatible
computers. A computer connecting cable is included with the Starter Pack. The supplied
cable is of male to female gender, to connect your MFJ-1278B to the computer.
For other computers with a 25-pin RS-232C port, consult the manual for your computer or
accessory to see which pins it uses to send and receive data on, as well as the pin used for
signal ground. Follow the computer manufacturer's recommendations for connecting the
serial port to a modem. You may also find the technical information in this section useful.
Your MFJ-1278B is configured as Data Communications Equipment (DCE), the technical
term for an RS-232C modem. Most computers are configured as Data Terminal Equipment
(DTE). If this is the case for your computer, you may be able to wire pin 2 of the MFJ-
1278B connector to pin 2 of your computer's RS-232C port. Then wire pin 3 to pin 3 and pin
7 to pin 7 on the computer's RS-232C port. You can provide these connections with a
standard 3-wire male-to-female or male-to-male RS- 232C extension cable, depending on
whether your computer has a DB25S or DB25P connector.