Thanks for Kai Ruottu's detailed explaination. The method of adding a new target template seems too professional for me. So I have to give up the idea to install gcc 4.x on alpha-dec-osf1. On the other hand, what I need is to install g95 on alpha-dec-osf1 and g95 only needs libbackend.a and libgcc.a from gcc, I figure out two ways that might work: (1) build gcc 3.x and then try to build g95; or (2) build gcc-4.0.3 on supported new system, i.e. alpha-dec-osf5.1d, copy the needed files (libbackend.a and libgcc.a) back to alpha-dec-osf1, and then build g95. Any suggestions? Jun Xiong