You cannot build GNU CC (or GNU Pascal) by itself on MS-DOS; it will not compile under any MS-DOS compiler except itself. The official MS-DOS port of GCC is called djgpp, and it is available from `simtel.coast.net' and it's mirrors all over the world. The `configure' script is replaced by an MS-DOS batch file called `configure.bat' wich does essentially the same. A pre-configured source distribution should be available from the same site where you got djgpp.