\section{Design Desicions} \subsection{Howto save the return address of a call} stack or linkregister \subsection{howto implement uart, timer, \ldots} extension module vs. other \subsection{how does we define cmp on unsigned values} see note in conditions. there is a difference between x86/amd64/avr and arm. we will very likely go with arm (or?) \subsection{big/little endian}