Long overdue, I finally got to give this a try. It worked great!!! I prepared some notes since I know I'll forget the steps, and I'm putting them here for future use.
I used a Windows XP computer with a hardware serial port. I'm unsure how much flow control plays into this, as at 9600 baud I think both the controller and PC keep up quite well. You could likely ignore flow control and just use Rx, Tx and 0V lines.
On robot teach pendant: Menu > File > File > [UTIL](F5) > Set Device (1) > Floppy disk (1) Run CMD.exe cd to kfloppy.exe folder run kfloppy.exe Setup > Port Settings, modify as appropriate. Did not have to change defaults for RJ3iB, only port number. File > Change Directory, move to an appropriate folder (preferably other than the executable folder). For backing up programs: On the PC: Create an empty folder through windows explorer or command line, then change directory in kfloppy (as shown above) into this folder. On the robot: Menu > File > File > [BACKUP](F4) > your choice of files to transfer Note: I had a repeating error where the file cannot "open for read". This is likely due to *.TP not being ASCII readable. The log file "KFLOPPY.LOG" will be automatically generated and also placed into the directory with the backup files. For sending programs: On the PC: Create an empty folder through windows explorer or command line, place your file to be sent there, then change directory in kfloppy (as shown above) into this folder. On the robot: Menu > File > File > scroll down to the extension of file to transfer (I did not have luck transferring all file types, but I am unsure why) [LOAD](F3), then you should see a prompt to agree to transfer the file you are trying to load What is happening here? This utility was apparently written outside FANUC with the intention of emulating an RS-232 capable floppy drive. You are configuring the program with the correct parameters so that the controller can see it on the UART, then dumping programs to the "floppy" or requesting programs from the "floppy".
If I ever get bored, I might try to create a 64-bit compatible version of this that will work with USB<>UART converters. But no promises, I'm rarely bored