PRODUCT ID: 50
We sure love the ATmega328 here at Adafruit, and we use them a lot for our own projects. The processor has plenty of GPIO, Analog inputs, hardware UART SPI and I2C,...
PRODUCT ID: 123
This is a preprogrammed Atmega328P chip, useful if you want to make your own Arduino-compatible or repair a damaged chip on an exisiting Arduino UNO, Duemilanove, Diecimila, or NG!