To the original question regarding why porting is sometimes difficult, IBM has a good two-part article on some bad assumptions people make that complicate porting from 32-bit to 64-bit. Worth a read if you ever have to do that type of work: http://www-128.ibm.com/developerworks/power/library/pa-ctypes1/ http://www-128.ibm.com/developerworks/power/library/pa-ctypes2/ Enjoy, Matt