FLASH MEMORY WITH REDUCED ERASING AND OVERWRITING

摘要

A semiconductor mass storage system can be substituted for a rotating hard disk. The system avoids an erase cycle each time information stored in the mass storage is changed by programming any changed data file into an empty mass storage block rather than over itself. Periodically the mass storage will need to be cleaned up. Even use of all blocks is provided by using several flags (622-628), a map to correlate a logical address of a block to a physical address (630) and a count register (620) for each block. Flags indicate defective blocks (624), used blocks (626), old versions of a block (628), and erase inhibit (622). A counter (620) is used to determine the amount a block has been erased and written. Reading is performed by providing a logical address and sequentially comparing it with the mapped logical addresses.