Non-volatile memory data protection
US6556476B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Mar 11, 2002 |
| Grant date | Apr 29, 2003 |
| Priority date | — |
| Expiry date | Mar 11, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C16/22
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A write-protected memory device has two write modes. Such memory device has many memory cells organized into pages. A normal write mode checks a one-bit flag collocated with every memory cell to see if writes are allowed. If the flag indicates a write operation to that memory cell is allowed, the flag is toggled and the cell is written. If the flag has previously been toggled, the write operation is prevented. A special write mode allows write operations to memory cells regardless of the state of the one-bit flag. The special write mode can be discerned in hardware by the loading of a register with a reprogrammable password, or the splitting of a normal single write-enable pin into two independent pins, e.g., normal write and special write. The memory operations can proceed either in page mode or cell-by-cell
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.