Dave McGuire wrote: Is it possible to explain what the magic does? More precisely: what is the difference between an .a and an .so library? I detailed this a few posts ago. .a is a static library, .so is a shared library. How on earth does -lpcap point to /usr/lib? -lpcap tells the linker to look in every directory in the library search path to find either libpcap.a or libpcap.so. This library lives in /usr/lib on most systems, but the simh makefile hard-coding that path (and hard-coding it to only find the static library) is a big mistake. It is, but why not just symlink it for the time being? Peace... Sridhar