Fortran Programming Guide

Fortran Unformatted I/O for Tape

Using the Fortran I/O statements to connect a magnetic tape for unformatted access is less satisfactory. The implementation of unformatted records implies that the size of a record (plus eight characters of overhead) cannot be bigger than the buffer size.

As long as this restriction is complied with, the I/O system does not write records that span physical tape blocks, writing short blocks when necessary. This representation of unformatted records is preserved (even though it is inappropriate for tapes) so that files can be freely copied between disk and tapes.

Since the block-spanning restriction does not apply to tape reads, files can be copied from tape to disk without any special considerations.