Actel was a company that makes FPGAs. They are now part of Microsemi.
See http://www.microsemi.com/products/fpga-soc/fpga-and-soc for more information on their FPGAs and SoC parts. One main difference between Actel FPGAs and other brands is Actel's are non-volatile; i.e. they don't require loading before use after power-one.