The following drawing is how wiring for a "null modem" is done, regardless of computers in use. The pin numbers refer to the "RS-232" pin designations (most 25 pin connectors on computers are RS-232 configuration). Computer #1 Computer #2 Pin # Pin # =========== =========== 2 ----------------------------- 3 3 ----------------------------- 2 4 --\ /--4 5 ---|connect these together|---5 8 --/ \--8 6 \_ connect these together _/6 20/ \20 7-------------------------------7 NOTE: Do NOT tie the common lines (IE. 4,5,8 or 6,20) from one computer to the other, just make the common tie in the respective connector. Transferring Files ------------------ To transfer files between two different TYPEs of computers (IE. IBM PC and MAC) you can simply use a terminal program on each computer (set to the specific communications port) and use that software to transfer info using a standard file transfer protocol. If you are using MS/PC-DOS machines the following will work (assuming COM1 is being used on both machines): Type the following information on BOTH machines: MODE 9600,N,8,1 Type the following information on the RECEIVING computer (this will tell the computer to take the information FROM COM1 and put it into a file called FILENAME.TXT on C: drive): COPY COM1: C:FILENAME.TXT Type the following information on the SENDING computer (this will send a file called FILENAME.TXT on C: drive to COM1): COPY C:FILENAME.TXT COM1: When the file transfer is done, the receiving computer will display a message indicating the file was copied successfully. Macs support higher baud rates. Zmodem is faster than Xmodem or Ymodem. If you don't have Zmodem, Xmodem with 1K blocks is faster than standard 128 Byte Xmodem. Ymodem and Zmodem batch can specify a group of files to transfer.