Actually, the structure of my program is basically there. I am starting to think that binary files are much more complicated than they've been described. I probably wouldn't have given it so much thought, but I started with a binary file that was extracted to an ASCII text file by a program written by someone else. The original file was 90 MB, and the ASCII text file it became was over 250 MB. When I use Visual Basic to convert it back to binary, the file only shrinks to about 190 MB. I don't think the extraction program does it's thing by "decompressing" the data, but merely changing its format. So I'm absolutely sure I'm missing something important somewhere.