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Non volatile memory in fx-5800P

fx-5800P

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#1 Tritonio

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Posted 08 September 2019 - 08:11 PM

Does anyone know how often fx-5800P stores a backup of the RAM (programs, formulas, variables etc) to flash? Also, is it flash or some other EEPROM? Also, what does the P button on the back do on this calculator? It does not reset settings or anything else, but I think it force-reloads the RAM from the non volatile storage, is that correct?



#2 pan.gejt

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Posted 09 September 2019 - 05:11 AM

According to the UG (page E-1) the P button is used to initialize the calculator after removing the insulation sheet.



#3 Tritonio

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Posted 09 September 2019 - 08:23 PM

But what does it really do under the covers? Does it copy from EEPROM/flash to RAM? Does it erase RAM and EEPROM (pretty sure it does not). IIRC the manual says to press the button also after changing batteries so I am lead to believe that it copies from EEPROM to RAM.

 

But what I really don't know, is the first part of my question: when and how often does this calc save to EEPROM? Does it have an expiration date (e.g. after 100.000 turn offs the EEPROM will be broken)



#4 Tritonio

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Posted 11 September 2019 - 03:55 PM

So the manual on page E-135 says that the calculator will return to the state it was when you last turned it off if you press the P button on the back. So I assume that means that it saves the RAM contents (programs, variables etc) to EEPROM (or flash, whatever it is) on every shutdown. EEPROMs should do 100K write cycles easily so if you turn off/on 10 times a day your calculator, it should last 100K/10/365= 27 years before the EEPROM gives out. Impressive. Or if you want it to last 10 years, you'd need to turn it on/off 27 times a day. Hehe. I wonder what it does when the memory starts failing though? If it is clever enough, it won't have a problem working, it will simply lose the data when changing battery.







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