FreeRTOS Homepage
FreeRTOS.orgTM is a portable, open source, mini Real Time Kernel - a free to download and royalty free RTOS that can be used in commercial applications (see license text). This site shows how a complete embedded real time system can be created from a Windows host using quality open source development tools (where available). See the FreeRTOS.org features summary.
http://www.freertos.org/portcygn.html
Cygnal (Silicon Labs) 8051 Port
The Cygnal port was developed on a C8051F120-TB prototyping board fitted with a 8051F120 microcontroller. The freeware SDCC compiler was used along with the Cygnal IDE.
The included demo application creates 21 real time tasks and uses an LED array wired to port 3 for eight 'flash' tasks.
As downloaded this demo application does not demonstrate the use of co-routines. See the co-routine documentation page for information on how co-routine functionality can be quickly added to this demonstration.