Obviously written by a "technical writer", in other words someone who does not have a clue as to what he is writing about. My boss is a technical writer, I write up the specs, he re-writes it, then I edit it to retain the actual meaning.

KF4HAZ - Lonnie

----- From: "John Hansen" <hansen@

> I've had quite a bit of experience with 16F series PICs but am just getting 
> started with 18F series PICs.  In the datasheet for the 18F252 I found the 
> following language:
> 
> ==================snip===========
> For this reason, variables that change infrequently (such as constants, 
> IDs, calibration, etc.) should be stored in FLASH  program memory.
> 
> Note: If data EEPROM is only used to store constants and/or data that 
> changes rarely, an array refresh is likely not required.
> 
> ===================snip==============
> 
> This seems to me to be a contradiction.  In the first section it says that 
> EEPROM is to be used for values that change frequently and that flash 
> program memory should be used for values that don't change frequently.  In 
> the second section it seems to be saying that it is just fine to store 
> constants and values that change infrequently in data EEPROM.  Does anybody 
> know which of these is correct?
> 
> Elsewhere the data sheet says that EEPROM retention is 40 years or 
> better.  Then there is that rather peculiar specification D124 that says 
> that you need to perform a refresh every 1 to 10 million Erase/Write 
> cycles.  But wouldn't an Erase/Write cycle constitute a refresh?  And why 
> refresh every 1 to 10 million Erase/Write cycles when according to the 
> datasheet the part is only rated for 1 million write cycles?
> 
> Can anyone shed any light on this?
> 
> Thanks,
> 
> John Hansen.
> 
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