There is a beta release of RobotBASIC available for testing USBmicro
U401 and U421 devices. The details of the release are available here:http://www.circuitgizmos.com/wordpress/index.php
This is a beta version of the program released so that people that
want to use the U401 and U421 devices with RobotBASIC can test out
RobotBASIC before the official release of the program.
The program shows this disclaimer:
This is a Beta Trial release for people who want to try out the
support for the USBmicro U4×1 devices.
Please check www.RobotBASIC.com
for news on the final release version.