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 uart02, the difference is that this is primarily thumb code instead of ARM. ARM in this case meaning the traditional 32 bit instruction set and thumb meaning the traditional 16 bit instruction subset. Thumb2 has confused/blurred those definitions though. (thumb2 is a mostly 32 bit extension to the thumb instruction set using formerly undefined instructions to create variable word length instructions). You have two choices you can use my bootloader with the uart03.hex file or copy the uart02.bin file to (overwrite the) kernel.img on your raspi sd card. (might want to back up that file if you want to go back to running linux with it later, or download a replacement from the net). 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 echos back.