anchor.diff:                 (namestring dest))
         t
         (multiple-value-bind (source-dir source-cluster source-start) (open-file-metadata host source)
  -        (assert source-start (source-start) "Source file not found. ~s" source)
  +        (error 'simple-file-error
  +               :pathname source
  +               :format-control "File ~A does not exist. ~S"
  +               :format-arguments (list source (file-name source)))
           (multiple-value-bind (dest-dir dest-cluster dest-start) (open-file-metadata host dest)
  -          (assert (not dest-start) (dest-start) "Destination file alredy exist. ~s" dest)
  -          (let ((dest-offset))
  +          (let ((fat32 (fat-structure host))
  +                (fat (fat host))
  +                (disk (partition host))
  +                (dest-offset))
  +            (when dest-start
  +              (remove-file dest-dir dest-start disk dest-cluster fat32 fat))
               (multiple-value-setq (dest-offset dest-dir)
                 (create-directory-entry dest-dir
                                         (pathname-name dest)
                                         (pathname-type dest)
                                         (eql (pathname-version dest) :previous)
  -                                      (bytes-per-cluster (fat-structure host))))
  +                                      (bytes-per-cluster fat32)))
               ;; copy meta data
               (replace dest-dir source-dir
                        :start1 (+ dest-offset 11)
  
positive.code:          (fat32 (fat-structure host))
           (fat (fat host)))
      (multiple-value-bind (parent-dir parent-cluster file-offset) (open-file-metadata host path)
        (assert file-offset (file-offset) "File not found. ~s" path)
        (remove-file parent-dir file-offset disk parent-cluster fat32 fat))))
  
  (defmethod delete-directory-using-host ((host fat32-host) path &key recursive)
  
negative.code:           (= signature #x29))
        signature
        (error "Bad signature : ~x .
  Valid signature are #x28 and #x29" signature)))
  
  (defun check-bps (bps)
    (unless (= bps +bootable-partition-signature+)
  