System and method for RAM power and data backup utilizing a capacitor and ROM
US5608684A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 13, 1994 |
| Grant date | Mar 4, 1997 |
| Priority date | — |
| Expiry date | Oct 13, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C11/005
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A system and method for permanently backing up RAM memory devices. The present invention utilizes a capacitor as a primary backup device for supplying the necessary backup power for power fluctuations, power interruptions, and other short-duration power failures. The present invention also utilizes a ROM as a secondary backup device for backing up and restoring valid RAM data when the duration of power loss is greater than that for which the capacitor can supply backup power. Thus, the integrity of RAM data is guaranteed for all types of power fluctuations, interruptions, and failures. The ROM includes two storage areas for separately storing two copies of RAM data. The processor first determines whether the data stored in the RAM is valid. If the present RAM data is valid, the processor backs up the present RAM data by replacing the oldest or invalid copy in the ROM with the present RAM data. If the present RAM data is not valid, the processor restores the RAM data with the most recent valid data previously stored in the ROM.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.