I was talking about format, in addtion to fdisk. I don't use Microsoft much anymore, but when I was learning, there was a switch for format , "format C: /f " IIRC, the /f meant it would actually write "f''s to the entire partition, essentially writing 1's to the entire partition. Dos 6's format was the last one that did it right, in my observation, concerning overwriting sectors marked bad, etc. I stopped using Windows for this very reason. I never looked back, and don't want to deal with Microsoft secrecy anymore.