It seems to me that not many PIC users use an embedded OS/RTOS. However if we go up the ladder and use 32bit microprocessors like ARM9/XScale/ColdFire/etc then often an OS/RTOS is used (typically with external Flash and SRAM/SDRAM). Just wondering which RTOS the list members use. It seems to me that Linux/WindowsCE are getting more coverage but expensive RTOS like VxWorks/ThreadX/etc are still very popular. Xiaofan -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist