See the top level README for information on where to find the schematic and programmers reference manual for the ARM processor on the raspberry pi. Based on uart01, this one enables the uart rxd1 receiver (gpio15). It starts by printing 12345678 then whatever you type on the terminal is echoed back. You will need something like this http://www.sparkfun.com/products/718 to connect to the uart pins on the raspi. Do not connect the raspberry pi pins directly to a com port on a computer you will fry the board. The above board happens to have pins in the same order as the raspberry pi. On connector P1 on the raspberry pi connect pin 6 to ground on the usb to serial board. Pin 8 on P1 to RX on the usb to serial board, and pin 10 on P1 to TX on the usb to serial board. Using a dumb terminal (minicom) 115200 board No parity 8 bits 1 stop bit, no flow control (might have to exit minicom and start again for the flow control setting to take). What you type on the dumb terminal comes back.