DataFlash is a low pin-count serial interface for flash memory. It is an Atmel proprietary interface, compatible with the SPI standard.
Information is written and read from a DataFlash chip using any microcontroller, such as the Atmel AVR, the Microchip PIC or the ARM. The Boot ROM of numerous Atmel ARM microcontrollers support downloading code from DataFlash chips after reset.
The AT26 series DataFlash chips are software-incompatible with the original AT45 series chips. They use a simpler command set, supported by other vendors of serial flash but omitting SRAM buffers and other features that make AT45 chips simpler to support. On this page, only the original AT45 series chips will be called DataFlash; in this case, brand-oriented marketing creates needless technical confusion.
Read more about Dataflash: Examples of DataFlash, Comparison Between DataFlash, EEPROM and MMC/SD, Example C Source Code To Interface To DataFlash