Sony PCG-R505ECP Online Help Center (VAIO User Guide) User Manual page 23

Write-protecting a Memory Stick media
Memory Stick media is designed with a write-protect tab to protect valuable data from accidental erasure or overwriting.
Move the tab to the right or left to set or release write-protection.
Write-protect off Data can be saved on the Memory Stick media.
Write-protect on Data can be read from but not saved on the Memory Stick media.
Using the Write- protect Tab
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