h6. [[OS SWI Calls]] h6(. » [[OS_File]] h6((. » OS_File 24 h2. OS_ File 24 h5. (SWI &08) |_<^{width:3em}. Entry | | |<^. R0 |<^. 24 (reason code) | |<^. R1 |<^. Pointer to filename | |_<^{width:3em}. Exit | | |<^. R0 |<^. Preserved | |<^. R1 |<^. Preserved | |<^. R2 |<^. Natural block size in bytes| h4. Use The purpose of this call is to find the natural block size of a given file. h4. Notes When you create or extend a file, disc space can only be allocated in chunks of a minimum size (512 bytes, for example). If your file is just 1 byte long for example, 511 bytes of disc space may have to be wasted after it if the natural block size is 512. h4. See also * [[OS_File]]