MC68HC11D3 Technical Data INTRODUCTION,The MC68HC11D3 and MC68HC11D0 are ROM-based high-performance microcontrollers (MCUs) based on the MC68HC11E9 design. Members of the Dx series are derived from the same mask and feature a high speed multiplexed bus capable of running at up to 3 MHz, and a fully static design that allows operations at frequencies to dc. The only difference between the MCUs in the Dx series is whether or not the ROM has been tested and guaranteed.