In a flash EEPROM system that is divided into separately erasable blocks
of memory cells with multiple pages of user data being stored in each
block, a count of the number of erase cycles that each block has endured
is stored in one location within the block, such as in spare cells of
only one page or distributed among header regions of multiple pages. The
page or pages containing the block cycle count are initially read from
each block that is being erased, the cycle count temporarily stored, the
block erased and an updated cycle count is then written back into the
block location. User data is then programmed into individual pages of the
block as necessary. The user data is preferably stored in more than two
states per memory cell storage element, in which case the cycle count can
be stored in binary in a manner to speed up the erase process and reduce
disturbing effects on the erased state that writing the updated cycle
count can cause. An error correction code calculated from the cycle count
may be stored with it, thereby allowing validation of the stored cycle
count.