This particular ATmega328P-20PU comes programmed and tested with the Arduino Firmware.
The Atmel AVR ATmega328 is used as the heart of many Arduino / Freeduino microcontroller development boards. The ATmega328 runs pretty much the same speed, with same pinout, but features more than twice the flash memory (30k vs 14k) and twice the EEPROM (1Kb vs 512b) of the ATmega168.
This particular ATmega328P-20PU comes programmed and tested with Arduino Firmware which is ready to drop into any standard DIP-mount Arduino-compatible board, like our own Freeduino or Boarduino kits.
Please Note: This product now comes with the Arduino 1.0 optiboot bootloader programmed into it. When programming via the Arduino IDE please select "Arduino Uno" under the Tools -> "Board" category instead of "Arduino Duemilanove w/ ATmega328". This bootloader not only has faster upload speeds but is now backwards compatible with products that use a FTDI USB-TTL converter chip.
The AVR series of microcontrollers are right up there with Microchip PIC products. Powerful, inexpensive, and programmable with some very good open source software (look up GCC), with a vibrant user community.
Here are more key features: