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| How to build your own 0-modem |
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A 0-modem is a cable used to link two computers together in order to exchange DATA, using standard COM ports. For example you could copy files from one computer to another using such a cable. Many games, like Doom and Quake, provide the opportunity to play against a life opponent using a 0-modem. You can buy a 0-modem for a small price, but for about the same amount you can construct your own one, which is more exciting.
A 0-modem can contain 3 or 7 wires. The 3-wire model will work with most software, but some programs demand a 7-wire model. So build one with 7 wires.
Standard COM ports can have two different appearances: 9 pin male D-connector and 25 pin D-connector. Both have the same function, from the 25 pin model, only 9 pins are used!
Have a look at the COM ports of the two computers you want to connect. Do you need a 0-modem with 9 pin connectors? Or 25 pin connectors? Or one 9 pin and one 25 pin connector?
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)
Here are some programs you can use with your newly created 0-modem:
| FastLynx | a program to copy files from one computer to another. You have to run the program on both computers. |
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| download: FX.ZIP (72 KB) | |
| Commutes | a 0-modem 'chat' program. My own creation! Text you type, appears on your screen and on the 'connected computer's' screen. |
| download: COMMUTES.ZIP (5 KB) |