The following example demonstrates flushing the disk cache of given binary file, so that data is guaranteed to be written to the disk.

Example:
procedure TForm .Button Click(Sender: TObject);
var
  f : file;
  i : integer;
begin
  i :=  0;
  AssignFile(f, 'C:\DownLoad\Test.Bin');
  ReWrite(f,  );
  BlockWrite(f, i, sizeof(i));
  FlushFileBuffers(TFileRec(f).Handle);
  CloseFile(f);
end;