The difference binmode makes in DOS and Windows is crucial! Without binmode, all routines have to do (roughly speaking) two things; 1. did we just read a OD OA pair? (if yes, convert to '\n', 2. did we just read end of file? (if yes, stop. In binmode, all we care about is end-of-file. Even end-of-file can cause a problem if there is an embedded ^Z in the file (original DOS end-of-file mark--ignored in binmode.) And since these are implemented in the OS at root (thin wrapper in 'C' library) the distinction is important...

--hsm