Flash and EEprom

[terry]

Hi,

What is the difference between flash memory and eeprom? Which one is more reliable?

Thanks!

 

[Al Borowski]

Hi,

What is the difference between flash memory and eeprom?

As far as I know, with EEPROM you can erase/reprogramme individual
bytes. You can only erase/reprogramme Flash in banks of many bytes. Use
google for more details.


Which one is more reliable?

No idea - look at some datasheets.

cheers,

Al

 

[John Smith]

As far as I know, with EEPROM you can erase/reprogramme individual bytes.
You can only erase/reprogramme Flash in banks of many bytes. Use google
for more details.


Which one is more reliable?

No idea - look at some datasheets.

cheers,

Al

Also, if what I've been using is typical, flash has a write-life. That is,
after so many erase/write cycles (50,000) it may begin to fail.

John

 

[Tim Wescott]

Also, if what I've been using is typical, flash has a write-life. That is,
after so many erase/write cycles (50,000) it may begin to fail.

John

Both flash and EEPROM have write lives (in cycles) and data retention
lives (in years). The basic cell AFAIK is the same, so for recent
technology devices they will have comparable lives. The difference is
that the flash part saves a lot of real estate with it's block erase, so
in general if the chip has a lot of memory it'll be flash and if it has
only a little it'll be EEPROM.

In fact, for "big" chunks of memory I don't know of anything _but_ flash
being currently available, and the little 256-byte 8-pin parts are all
EEPROM for convenience in parameter storage. There are older EEPROM
chips, but that's only because EEPROM came along several years before
flash did.

 

[John Smith]

Both flash and EEPROM have write lives (in cycles) and data retention
lives (in years). The basic cell AFAIK is the same, so for recent
technology devices they will have comparable lives. The difference is
that the flash part saves a lot of real estate with it's block erase, so
in general if the chip has a lot of memory it'll be flash and if it has
only a little it'll be EEPROM.

In fact, for "big" chunks of memory I don't know of anything _but_ flash
being currently available, and the little 256-byte 8-pin parts are all
EEPROM for convenience in parameter storage. There are older EEPROM
chips, but that's only because EEPROM came along several years before
flash did.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Thanks, Tim. I didn't know that.

John

 

[Terry Given]

Thanks, Tim. I didn't know that.

John

I once peer-reviewed a design which periodically "refreshed" a couple of
EEPROM locations. Turns out the idea used up the entire life of the chip
in about 3 weeks. oops. They re-designed the firmware, scrapping the
not-so-brilliant idea.

AFAIK the failure method is increased write cycle time.

Cheers
Terry

 

[Rich Grise]

I once peer-reviewed a design which periodically "refreshed" a couple of
EEPROM locations. Turns out the idea used up the entire life of the chip
in about 3 weeks. oops. They re-designed the firmware, scrapping the
not-so-brilliant idea.

AFAIK the failure method is increased write cycle time.

So, you're saying, you could use them for the program store for embedded
Linux, which gets an update about once a year, but not Windows, because
the updates would wear them out in a few weeks? ;-)

Cheers!
Rich

 

[Terry Given]

So, you're saying, you could use them for the program store for embedded
Linux, which gets an update about once a year, but not Windows, because
the updates would wear them out in a few weeks? ;-)

Cheers!
Rich

unless you update your windows system as infrequently as I do

Cheers
Terry