The Arduino Nano is a small, complete, and breadboard-friendly board based on the ATmega328 (Arduino Nano 3.x) or ATmega168 (Arduino Nano 2.x). It has more or less the same functionality of the Arduino Duemilanove, but in a different package. It lacks only a DC power jack, and works with a Mini-B USB cable instead of a standard one. The Nano was designed and is being produced by Gravitech.
FEATURE:
Microcontroller
Atmel ATmega168 or ATmega328
Operating Voltage (logic level)
5 V
Input Voltage (recommended)
7-12 V
Input Voltage (limits)
6-20 V
Digital IO Pins
14 (of which 6 provide PWM output)
Analog Input Pins
8
DC Current per IO Pin
40 mA
Flash Memory
16 KB (ATmega168) or 32 KB (ATmega328) of which 2 KB used by bootloader
SRAM
1 KB (ATmega168) or 2 KB (ATmega328)

The Arduino Nano is a small, complete, and breadboard-friendly board based on the ATmega328 (Arduino Nano 3.x) or ATmega168 (Arduino Nano 2.x). It has more or less the same functionality of the Arduino Duemilanove, but in a different package. It lacks only a DC power jack, and works with a Mini-B USB cable instead of a standard one. The Nano was designed and is being produced by Gravitech.
FEATURE:
Microcontroller
Atmel ATmega168 or ATmega328
Operating Voltage (logic level)
5 V
Input Voltage (recommended)
7-12 V
Input Voltage (limits)
6-20 V
Digital IO Pins
14 (of which 6 provide PWM output)
Analog Input Pins
8
DC Current per IO Pin
40 mA
Flash Memory
16 KB (ATmega168) or 32 KB (ATmega328) of which 2 KB used by bootloader
SRAM
1 KB (ATmega168) or 2 KB (ATmega328)