PRODUCT DESCRIPTION SST89C54 and SST89C58 are members of the FlashFlex51 family of 8-bit microcontrollers. The FlashFlex51 family is a family of embedded microcontroller products designed and manufactured on the state-of-the-art SuperFlash CMOS semiconductor process technology. As a member of the FlashFlex51 controller family, the SST89C54/58 uses the same powerful instruction set, has the same architecture, and is pin-for-pin compatible with standard 8xC5x microcontroller devices.