It has 14 digital inputoutput pins of which 6 can be used as pwm outputs 6 analog inputs a 16 mhz crystal oscillator a usb connection a power jack an icsp header and a reset button. The arduino uno is a microcontroller board based on the atmega328.
Arduino Uno R3
Nice Drawings Of The Arduino Uno And Mega 2560 Wayne And Layne
Arduino Blink
Arduino Uno Wiring Diagram Wiring Diagram
