To transfer files to the system using ZModem over serial you can use the zm.exe
program added to the FreeDOS install as a client. You will need a ZModom host on
another computer to send it files.

For Windows:
    Tera Term - Open File-Transfer-ZMODEM and select all the files to transfer
For Mac/Linux:
    lrzsz - Run "sz -f $(find -type f) > /dev/ttyUSB0 < /dev/ttyUSB0" in the
            directory containing all the files you wish to send.

Both options will require changing settings to specify your serial port and
configuring speeds. 9600 buad, 8 bits, None parity, 1 stop bit would be the
recommended settings.

To receive on the FreeDOS system:
    1. `cd` to the directory to put the files in.
    2. On the host system begin the file transfer.
    3. Then run `zm -c1 -b9600 -s rz` to recieve files over COM1 at 9600 baud
       on the FreeDOS computer.
