So we've run into our first real snag on the conversion road from 32 to 64 bit. We write out a binary file full of data and then read it back in using fwrite and fread. My file format is pure binary and it's as follows: Long height Long width For (short; height * width) Long Long So in the 32 bit world, this works great. But when trying to read these 32 bit files into software on the 64 bit systems, I'm running into problems! There are no delimeters in my file that I can use to determine which arch the file was written on. What I need is some kind of method to determine the arch, possibly based on the file??? I don't know??? All I need to know is, from the code level, if it's a 32-bit binary file or a 64-bit binary file? Thanks, -b