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XC164CM
System Units (Vol. 1 of 2)
Memory Organization
Passwords and Security Code
All protection feature control (install, disable, re-enable) is accomplished through
command sequences similar to the program/erase sequences (see Table 3-5). The two
command sequences that temporarily suspend the protection feature are additionally
secured by a password check sequence (64-bit security code) to ensure maximum
safety against undesired accesses.
During password checking, the four passwords entered via the command sequence are
compared to the four keywords (building the 64-bit security code) stored in the security
sector. If any mismatch is detected the respective protection feature remains active, the
sector(s) remain(s) locked, and a protection error (PROER) is indicated in the Flash
status register. In this case, a new Disable Sector Write Protection command or a
Disable Read Protection command is only accepted after the next system-reset.
User’s Manual
Memory_X41, V2.1
3-27
V1.2, 2006-03