Note: Pin D9 on the Arduino is not the same pin 9 on the ATmega328 IC. Pin 15 on the IC is actually the pin for Digital Pin 9 (D9) on the Arduino. If you want to see the pinout for the ATmega328 IC, ...

Original Circuit Diagram: Arduino UNO R3 Now ... an AVR chip with pre-charged bootloader! Atmega328-PU/ Atmega328P-PU – 1 16Mhz Xstal – 1 22pF Ceramic Capacitor – 2 Small Breadboard / Protoboard & ...

In one of the lowest spec examples of the last one, [gvl610] has got an up-to-date Linux kernel to boot on a vanilla Arduino Uno ... as the ATmega328 in the Uno has no MMU and is in to way ...