The free communications port you mentioned might be the answer to your question, but this will require a bit of research on your behalf in order to establish if this is possible.
Windows supports file sharing via the existing communications port or even your parallel port (LPT) – this method of sharing/transferring files is also know as Direct Cable Connection.
Since you haven't provided the Windows version you are using, I won't be able to give you specific instructions.
First, you need to find out if Macintosh computers support direct cable connections. In the case the operating system doesn't support it, then you could look at a few shareware/download sites for 3rd party programs that will do the job.
Once you have figured out what programs you can use for the file transfers, you need to check what protocols can be used for the communications part. The latest versions of Windows (Windows 2000, XP) support TCP/IP over direct cable connections, which mean the connection is treated in a similar way as a proper network connection where each host is assigned an IP Address! A quick look at the available options in your Windows system will help you determine what way you can establish the connection.
The second part is somewhat easier as it has to do with the physical medium, which will be used, that is, your serial cable. When transferring data between two serial ports (or communication ports) you need to use a special type of serial cable known as a x-over (pronounced 'crossover'). This special cable connects the TX (transmit) pin from one serial port, to the RX (receive) pin of the other and vice versa. You can purchase a x-over cable at a local electronic or computer store, or if you want to learn from the experience, try and make one yourself.
Because there are two different types of serial ports, DB9 and DB25, you will need to use different pin outs depending on what type of port your PC and MAC has available.
A quick visit to www.Firewall.cx (Networking--> Cabling--> Direct Cable Connection--> Serial Cable) will show you the cable pin outs you need to use for different serial ports (DB9 to DB25, DB9 to DB9, and DB25 to DB 25).
Once you have constructed your cable, or purchased it, you simply need to connect it to the computers and configure the software, share your drives and complete your file transfers.
This was first published in August 2003