Author concerns with SD memory cards and microcontroller Atmel ATmega128. He describes their architecture, features, properties and technology used in devices. He is mentioning principle of communication protocols used by SD card, through that cards can communicate with other connected devices. He analyzes the functionality of FAT file system. He describes the design and implementation of interfaces to connect the SD cards to microcontroller. He explains software solutions of this project and gives impartial view to usage and comparisons of implemented modes of communication witch card.