ATmega328 + Arduino Bootloader
[ARD-CPU328]

ATmega328 preburned with Arduino bootloader.

Summary

Microcontroller	ATmega328
Operating Voltage	1.8-5.5V
Digital I/O Pins	23 (max) (6 provide PWM output)
Analog Input Pins	6
DC Current per I/O Pin	40 mA
Flash Memory	32 KB (of which 2 KB used by bootloader)
SRAM	2 KB
EEPROM	1024 bytes
Clock Speed	20 MHz (max)

Programming
The Arduino CPU can be programmed by plugin it in Arduino Diecimila with the Arduino software (download). For details, see the reference and tutorials.