COMSOL Multiphysics 3.5a is a legacy version of the software released around 2008. It is not available as a free download
: Documentation for older versions like 3.5a is sometimes still available on academic or institutional repositories for those who still have valid licenses for legacy systems. for COMSOL 3.5a or info on modern system requirements for the latest version? COMSOL Client 6.4 for Windows® Comsol Multiphysics 3.5a Free Download