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Format 371

9.20 FORMAT

Menu Position MENU  5  Format

What it Does Formats the memory card, erasing all content and mapping
out corrupted blocks

Recommended Setting: n/a

Many people wonder what’s the purpose of formatting – after all, isn’t it
the same thing as deleting all the content off your memory card?
The answer is that formatting and deleting work completely different
internally, and do different things. Think of a memory card as a library, but
instead of storing books it stores image files. Libraries have a collection of
books on shelves, and a card catalog telling you where each book is
located.
Using this analogy, when you erase a book (image file) from the library, all
you do is remove the relevant card from the card catalog. It doesn’t
actually remove the book from the shelf; just the index card which points
to the book’s location. The book doesn’t actually get removed from the
shelves until a new book comes in to replace it. (Similarly, an old image
doesn’t actually get erased until a new image overwrites the old one). At
that time, the new book is added to the card catalog.

Hard as it is to believe, all digital storage media is imperfect, just like some
libraries have broken shelves and leaky ceilings where books cannot be
stored. And so the process of formatting was designed to identify these bad
shelves (known in computer terms as “bad blocks”). Using the Library
analogy, formatting a library involves removing all the books, taking note
of where the broken shelves are and where the roof leaks, painting the good
shelves, re-numbering all the shelves, and putting bricks in the card catalog
so you can never accommodate a card which points to those bad spots.
You’re then open for business.
Clearly, erasing and formatting are now two different things – erasing
actually leaves the image on your memory card. And they will stay there