KERMIT is the universal language for just about every old computer when it comes to transferring files. . Tandy m100, Apple2, CP/M, unix, DOS, Windows, what ever. It works over modem, telnet, ssh, direct serial. If you can send text over it you can send kermit.

Here is a kermit client for the Tandy m100.

The way I got this on my m100 was to copy it to a unix machine. Then dial it up with the m100's built in modem.
Have a copy of ta100.bas in the home directory of a computer can can dial/RS232 to.
With the m100 Connect and log in
type 'cat ta100.bas' but do not hit enter yet
On the m100 press F2 for DOWN. It will ask you for a file name type 'kerm'.
"Down" in the status bar should now be inverse. Press ENTER and watch the program stream down.
It will take a wile but when it is done press F2 again and then log out.
Exit out of term

Load BASIC
type 'load kerm.do'
It will take a wile to load. You should see "Wait" blink while it works. You may get a SN error at the end. That is likely your shell prompt that got caught in the download. No problem
Now type 'save kermit'
exit out of basic
There should now be a kermit.ba file in your m100's menu that you can run directly.
Good day


Below is the text that came with the ta100.bas from the author. 
_____________________________________
From: SAGE::MAILER 31-JAN-1986 00:23
To: SHAWN
Subject: Kermit protocol
[Netmail From: genrad!decvax!tektronix!pogo!dhs@mit-eddie] Kermit protocol
Here is a program that implements the Kermit protocol. I keep promising myself that I'll
re-write it with a little assembler to be a
whole lot faster. Oh well, it works. It also
give the ability to do a directory of FILES while connected to a modem. It works over the modem, and has been tested to run at 9600 baud through the RS232 port (with XON/XOFF Enabled).
Dave Straayer Here it is: -------cut here------