Which UNIX system? Which Fortran 77 on UNIX? Most UNIX Fortran compilers create unformatted files in a method that is compatible with that used by Visual Fortran, but if the UNIX system is "big-endian" (Sun, IBM, HP, SGI), you'll need to open the file with CONVERT='BIG_ENDIAN' to do the length and data conversion.
Thanks Steve. I got it now, that's quite stupid i think.
So when will I know that the unformatted sequential file can't be open by CONVERT='NATIVE' ? Cos I keep getting forrtl <22> now, but even if I set the recl = a very big number like 60000000, i still get the error.