The AT45DB021D is a 2.7V, serial-interface Flash memory ideally suited for a wide variety of digital voice-, image-, program code- and data-storage applications. The AT45DB021D supports RapidS serial interface for applications requiring very high speed operations. RapidS serial interface is SPI compatible for frequencies up to 66 MHz. Its 2,162,688 bits of memory are organized as 1,024 pages of 256 bytes or 264 bytes each. In addition to the main memory, the AT45DB021D also contains one SRAM buffer of 256/264 bytes. EEPROM emulation (bit or byte alterability) is easily handled with a self-contained three step read-modify-write operation. Unlike conventional Flash memories that are accessed randomly with multiple address lines and a parallel interface, the DataFlash u ses a RapidS serial interface to sequentially access its data. The simple sequential access dramatically reduces active pin count, facilitates hardware layout, increases system reliability, minimizes switching noise, and reduces package size.