The X84041 MPS E2 is an attractive alternative to the 'add-on' parallel or serial nonvolatile memories that have traditionally been used in microcontroller-based systems. It features 4K bits of serial E2PROM memory that is accessed via a standard parallel bus. The serial architecture of the X84041 provides a cost and space saving replacement for low density parallel devices. Its unique parallel bus compatible interface also offers an I/O-saving alternative to serial devices that typically require two or three control pins for communication purposes. Although the X84041 can be used to interface with practically any 8, 16, or 32-bit microcontroller, the code provided here is for the widely used 8051 family.