Shopping list
2 female D-connectors, 9 or 25 pins
2 housings for a D-connector
1 piece of cable, desired length, at least 7 wires
Welding the thing together
9-pin (25-pin) 9-pin (25-pin)
connector connector
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pin 5 (7) <--- (ground-to-ground) ----> pin 5 (7)
pin 3 (2) <-- (transmit-to-receive) --> pin 2 (3)
pin 7 (4) <------ (RTS-to-CTS) -------> pin 8 (5)
pin 6 (6) <------ (DSR-to-DTR) -------> pin 4 (20)
pin 2 (3) <-- (receive-to-transmit) --> pin 3 (2)
pin 8 (5) <------ (CTS-to-RTS) -------> pin 7 (4)
pin 4 (20) <------ (DTR-to-DSR) -------> pin 6 (6)
Software for 0-modem
