Originally posted by: MegaloManiaK
Sorry, Smartmedia cards are EEPROM, (electronicly eraseable programable read only memory). When you write data to a SM card it uses a transistor to push electrons through the membrane which then allows current to flow through the cell to store data. When you erase something the card reader applys charge to the erase circuit which then puts the electron back on its original side thereby erasing the cell. With your hard drive or a diskette or other magnetic media, when you delete a file the cell that the data is stored in is not removed (unless you use a program specificly to do this) instead it is flagged as empty so that the HD can write to that cell in the future. When you use an undelete program it goes in and changes the flag back to say that that data segment is in use, and then it can be read again. Thats why if you wait a long time before undeleting the file can be unrecoverable because the HD has already written to those sectors. Since the SM card removes the cell totaly you can not recover any data that has been deleted. Sorry but they are gone.:frown:
Originally posted by: dakels
Just as a hardrive or floppy disk, if the disk has been formatted for any other files have been written to the card then those files are gone for good.
This is not entireley true since most people just quick format. Quick formats just rewrite the disk header and create a new directory/partition structure. The areas with the old files are just set to be written over. Only a "zero all data" or "low level" format completely wipes all data. It literally goes over every sector and sets everything back to 0. Thats also why a long format can take several hours whereas a quick format only takes a few seconds to minutes. You cannot recover data via normal means like end user software from long low level formats but you can easily recover data from quick formats. Luckily most people never do long formats.
As for the electron microscope method. I don't know a whole lot about it but I do know that they can detect traces of data patterns from the platters themselves. Therefore even if a drive that has been smashed and the read mechaism is broke, they can still recover data by directly reading off the platters. There are different methods they use but I think that is he most extensive while other methods may be not much more complex then what a tech would do at an office. Prices for the electron microscope methods can run into enourmous costs like $2000-4000 per gigabyte of data. It may have gotten cheaper since the last time I looked into it, but access to a SET microscope is never cheap.
Originally posted by: MegaloManiaK
Sorry, Smartmedia cards are EEPROM, (electronicly eraseable programable read only memory). When you write data to a SM card it uses a transistor to push electrons through the membrane which then allows current to flow through the cell to store data. When you erase something the card reader applys charge to the erase circuit which then puts the electron back on its original side thereby erasing the cell. With your hard drive or a diskette or other magnetic media, when you delete a file the cell that the data is stored in is not removed (unless you use a program specificly to do this) instead it is flagged as empty so that the HD can write to that cell in the future. When you use an undelete program it goes in and changes the flag back to say that that data segment is in use, and then it can be read again. Thats why if you wait a long time before undeleting the file can be unrecoverable because the HD has already written to those sectors. Since the SM card removes the cell totaly you can not recover any data that has been deleted. Sorry but they are gone.:frown:
