9.4.6 Send Checksum

To write data to user zones that require authentication for write access (AM [1:0] = 01 or 00 in the access register), the host must first carry out the write user zone command $B0, after which the device will return a special status word: $62 $00. This indicates that the memory is unchanged and the device is waiting for the host to provide a valid checksum before initiating the write cycle. The host sends the checksum it has computed using the System Write command opcode $B4 with P1 = $02. Only if the checksum is valid will the device initiate the write cycle; furthermore, if the device receives an incorrect checksum, it will clear the authentication privilege.