The majority of embedded control systems require nonvolatile memory. Because of their small footprint, byte level flexibility, low I/O pin requirement, low-power consumption, and low cost, serial EEPROMs are a popular choice for nonvolatile storage. Microchip Technology has addressed this need by offering a full line of serial EEPROMs covering industry standard serial communication protocols for two-wire (I2C), threewire (Microwire), and SPI communication. This application note provides assistance and guidance with the use of Microchip Microwire serial EEPROMs. Topics include: chip select and program enable inputs; proper write sequence; resetting the state machine; and using a hardware SPI port for Microwire communication.