Nonvolatile semiconductor memory

Abstract

Abstract PURPOSE:To ensure the strict control for the time of replacement of a read-only memory (E<2>PROM) which can be electrically erased and written, by accumulating and storing the write indicating signals to be applied to the E<2>PROM in response to the address of the E<2>PROM. CONSTITUTION:A center device 20 controls terminal devices set at four remote areas and transmits data. The terminal devices have prescribed actions based on the transmitted data. The address signals ADR and write enable signals WE' transmitted to E<2>PROMs 11-14 from the device 20 are also sent to an E<2>PROM set opposite to the device 20. The erasing/writing frequencies carried out by the center 20 for addresses corresponding to E<2>PROMs 11-14 are written and stored to the address which is designated by the E<2>PROM10 with the signal ADR. The number bit 17 for each word of the E<2>PROM10 can cover the upper limit values 10<4>-10<5> of rewritable frequencies of E<2>PROMs 11-14. Such rewriting frequencies stored in the E<2>PROM10 are read out to outside when necessary as the read data RDT and used as the maintenance data for necessary counterplans.

Inventors

• 👤 Kenji Ichida
• 👤 市田　憲治

Bibliographic Details