Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
eprom_dump [2017/05/29 16:42]
lord_nightmare clean up table, and capitalization of acronyms. add note about damaged chips
eprom_dump [2017/05/29 16:44] (current)
lord_nightmare add note about vcc vs vih voltage
Line 5: Line 5:
 There are several techniques to try to recover bit-rotten data like this: There are several techniques to try to recover bit-rotten data like this:
   * Change temperature. Ex: People have reported success using a hair dryer or heat-gun on parts. This seems to work better than freezing parts does, maybe by '​boosting'​ via thermal noise the floating gate charge readout value?   * Change temperature. Ex: People have reported success using a hair dryer or heat-gun on parts. This seems to work better than freezing parts does, maybe by '​boosting'​ via thermal noise the floating gate charge readout value?
-  * Lower reference voltage: Lowering the VCC/​Reference voltage from 5v to below 4.97v or so lowers the '​threshold'​ for reading back floating gate charges, which can recover some bits which are just below the threshold. Too low of a voltage may make the chip malfunction,​ too high will not have any effect.+  * Lower reference voltage: Lowering the VCC/​Reference voltage from 5v to below 4.97v or so lowers the '​threshold'​ for reading back floating gate charges, which can recover some bits which are just below the threshold. Too low of a voltage may make the chip malfunction,​ too high will not have any effect. To prevent potential damage to the chip by having address/​control lines driven higher than VCC, the reference input '​high'​ (ViH) voltage for all pins should be lowered simultaneously,​ but this might not always be necessary.
   * Multiple reads and binary ANDing or '​voting'​ of the bits: dumping a chip several dozen/​hundred times and having each dump '​vote'​ for whether a given bit is 1 or 0, the most popular votes winning. Binary AND is simpler, but this causes problems if a bit should read as 1 and erratically reads as 0.   * Multiple reads and binary ANDing or '​voting'​ of the bits: dumping a chip several dozen/​hundred times and having each dump '​vote'​ for whether a given bit is 1 or 0, the most popular votes winning. Binary AND is simpler, but this causes problems if a bit should read as 1 and erratically reads as 0.
  
 
eprom_dump.txt ยท Last modified: 2017/05/29 16:44 by lord_nightmare
 
Except where otherwise noted, content on this wiki is licensed under the following license: CC Attribution 4.0 International
Recent changes RSS feed Donate Powered by PHP Valid XHTML 1.0 Valid CSS Driven by DokuWiki