The output of sdcc --version or the filenames of the snapshot versions of SDCC include date and its Subversion number. Subversion allows to download the source of recent or previous versions http://sourceforge.net/svn/?group_id=599 (by number or by date). An on-line source code browser and detailled instructions are also available there. SDCC versions starting from 1999 up to now are available (currently the versions prior to the conversion from cvs to Subversion (April 2006) are either by accessible by Subversion or by cvs).