Appendix E - RS232/Parallel Port Keying

Morse Academy supports RS232 and parallel port keying interfaces that are commonly used by other programs, e.g. the K1EA Contest Logging program. This interface is not the preferred one because it only supports a single frequency. The audio feedback tones of 300 and 1800 Hz for MA's games is not available. Still the ability to practice with the (P)roficiency session and generate examination tapes makes it desirable to support these interfaces.

The ports COM1 (3FCh), COM2 (2FCh), COM3 (3ECh), COM4 (2ECh), LPT1 (37Ah), or LPT2 (27Ah) can be selected for keying in the (O)ptions menu, when choosing the (T)one generator option E. The keyed port address is displayed in Hexadecimal. Morse Academy outputs a 1 to the port to close the key, e.g.

                        OUT  &H3FC,1            (in BASIC)

                        mov  AL,1               (in MASM)
                        mov  DX,3FCh
                        out  DX,AL

To open the key a zero is output to the port.

The pin outs for keying are:

          RS232 Ports             Pins 4 and 5 on a DB9 connector.
                                  Pins 7 and 20 on a DB25 connector.

                                  Minus nine (-9) volts indicates key open.
                                  Plus  nine (+9) volts indicates key closed.
                                  (note voltages may vary from 6 to 12 volts,
                                  depending on the PC manufacturer)

          Parallel Ports          Pins 1 and 17
                                  Zero volts indicates key open.
                                  Plus  five (+5) indicates key closed.
                                  (note voltages may vary, depending on the 
                                  PC manufacturer)

Direct connection of your PC to a transceiver is NOT recommended. Isolation is required between the PC and the equipment being switched. Interfaces such as that designed by Jim Talens (N3JT) are commercially available. Write to Jim Talens (N3JT), P.O. Box 19346, Washington, DC 20036.

By Joe Speroni