EEPROM questions

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Eric Christopherson

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May 25, 2015, 1:05:34 AM5/25/15
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1. Is the EEPROM used to save things with XW the same chip as the one used for the new EEPROM FS?
2. How many writes can the EEPROM(s) sustain? I'm not sure if they're garden-variety flash or something else.

Ingo Korb

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May 25, 2015, 4:33:35 AM5/25/15
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Eric Christopherson <echrist...@gmail.com> writes:

> 1. Is the EEPROM used to save things with XW the same chip as the one used
> for the new EEPROM FS?

Yes, but both write to different parts of the chip, so they do not
affect each other.

> 2. How many writes can the EEPROM(s) sustain? I'm not sure if they're
> garden-variety flash or something else.

The data sheet guarantees 100000 write/erase cycles, in practice it is
likely that you get more than that. For example someone who tested the
endurance of the EEPROM on an ATmega328 found that it took more than 1.2
million cycles before the first cell gave up. His code wrote and
verified at maximum speed and needed 47 days for that, the accesses from
a C64 shoubd be much slower than that.

So unless you plan to use the EEPROM FS as storage for a C64-based data
looger that you plan to run for many months or years you probably do not
need to worry about the number of write cycles.

-ik

Eric Christopherson

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May 25, 2015, 11:19:43 PM5/25/15
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Thanks. Actually, though, I just realized that I was wondering also
(and perhaps most importantly) about the EEPROM or flash where the
firmware is stored. Is that the same (with the same write/erase
cycle)?


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Eric Christopherson

Eric Christopherson

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May 26, 2015, 1:53:03 AM5/26/15
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Hmm. http://en.wikipedia.org/wiki/Atmel_AVR talks of program memory
being non-volatile flash, so I assume that's where the firmware goes.
And http://www.atmel.com/Images/Atmel-2549-8-bit-AVR-Microcontroller-ATmega640-1280-1281-2560-2561_Summary.pdf
says "Write/Erase Cycles:10,000 Flash", so I guess that is much more
limited in reusability than the EEPROM.

Is that essentially correct?

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Eric Christopherson

RETRO Innovations

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May 26, 2015, 1:54:58 AM5/26/15
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On 5/25/2015 10:38 PM, Eric Christopherson wrote:
> Hmm. http://en.wikipedia.org/wiki/Atmel_AVR talks of program memory
> being non-volatile flash, so I assume that's where the firmware goes.
> And
> http://www.atmel.com/Images/Atmel-2549-8-bit-AVR-Microcontroller-ATmega640-1280-1281-2560-2561_Summary.pdf
> says "Write/Erase Cycles:10,000 Flash", so I guess that is much more
> limited in reusability than the EEPROM. Is that essentially correct?
10K cycles is standard. That should suffice for years of upgrades. I've
used the same device for development for years, and no issues.

Jim



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