(Electrically Erasable Complementary Metal Oxide Semiconductor) A type of semiconductor device used in reprogrammable memory chips such as FPGAs, PALs and GALs. Non-EECMOS devices cannot be changed and must be replaced to incorporate enhancements, but EECMOS chips can be used in prototyping new systems that are rapidly changing as well as in field-upgradeable applications.

EECMOS devices are reprogrammed by applying an erase voltage to specific pins on the chip. The erase voltage clears the existing logic configuration and allows the device to be reprogrammed. See FPGA, PAL and GAL.