xfer9860 is the application that lets you transfer files to and from the calculator. xfer9860 has a command line interface, and is is written in C. libusb is used for USB communication.

As of version 0.2, xfer9860 allows you to upload files to your calculator, even quicker than Casio's FA-124. File download support is included, though experimental. It usually works fine with smaller files, up to 3-400kB, and there is no risk in trying :). xfer9860 should run on any platform that libusb∞ supports, including Linux, FreeBSD, MacOS and Windows (libusb-win32∞).

On information on how to install it, see InstallationInstructions.

Example run:
sh-3.2$ ./xfer9860 -u ~/src/testgcc/prog.G1A prog.g1a

xfer9860 v0.2 Copyright (C) 2007 Andreas Bertheussen and Manuel Naranjo.
[I] Found file: /home/andreas/src/testgcc/prog.G1A
[I] File size: 936 byte(s)
[>] Setting up USB connection.. Connected!
[>] Verifying device.. Done!
[>] Requesting fls0 capacity.. 1424464 byte(s) free.

[>] Starting transfer of call.g1a to fls0, 936 b, 4 packets..
[#]
[I] File transfer completed.

sh-3.2$