This is a bit-banging USB host controller for the Parallax Propeller microcontroller. It uses the standard 80 MHz clock. Both full-speed and low-speed devices are supported.
Detailed information about this code is available in usb-fs-host.spin.
See this blog post for more:
http://scanlime.org/2010/04/its-alive-bit-banging-full-speed-usb-host-for-the-propeller/