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'[PIC]: Flash vs. EEPROM'
2000\09\23@222605 by Bob Ammerman

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----- Original Message -----
From: Jim Robertson <spam_OUTnewfoundTakeThisOuTspamPIPELINE.COM.AU>
To: <.....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU>
Sent: Saturday, September 23, 2000 9:11 PM
Subject: Re: [PIC]


> Atmel and microchip might be trying to blur the lines but some of us care
> to remember what "flash" is and isn't.
>
> -Jim
>

Jim,

I can't take the suspense.

What _is_ and _isn't_ flash.

Maybe a bit of a history on EPROM vs. EEPROM vs. FLASH if you or some other
piclister knows.

Thanks,

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

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2000\09\24@011005 by Jinx

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> I can't take the suspense.

> What _is_ and _isn't_ flash.

> Maybe a bit of a history on EPROM vs. EEPROM vs. FLASH if you or
> some other piclister knows.

> Thanks,

> Bob Ammerman

Almost every search I tried produces manufacturer's links and
definitions. You may start your debating

http://webopedia.internet.com/TERM/E/EEPROM.html

EEPROM is similar to flash memory (sometimes called flash
EEPROM). The principal difference is that EEPROM requires
data to be written or erased one byte at a time whereas flash
memory allows data to be written or erased in blocks. This
makes flash memory faster.

http://webopedia.internet.com/TERM/f/flash_memory.html

A special type of EEPROM that can be erased and reprogrammed
in blocks instead of one byte at a time. Many modern PCs have their
BIOS stored on a flash memory chip so that it can easily be updated
if necessary. Such a BIOS is sometimes called a flash BIOS. Flash
memory is also popular in modems because it enables the modem
manufacturer to support new protocols as they become standardized

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2000\09\25@120250 by M. Adam Davis

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Flash memory is the same as eeprom except flash can be erased in blocks or all
at once, instead of a byte at a time.

I'm unaware if there are any patents or trademarks associated with it, I've
never seen any notices remarking such is the case.

Flash appears to be the generic term for any EEPROM which can be 'flash' erased.

-Adam

Bob Ammerman wrote:
{Quote hidden}

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2000\09\25@222129 by Jim Robertson

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At 12:02 PM 25/09/00 -0400, you wrote:
>Flash memory is the same as eeprom except flash can be erased in blocks or
all
>at once, instead of a byte at a time.

This is not what "flash" was. Flash was a variation on EPROM technology not
EEPROM. Essentially flash replaced the UV erasure with an electrical erase
mode so eproms started to look more like eeproms. Semantically of coarse flash
eprom is eeprom but we are dealing with history and the conventions used to
delineate between the two technologies.

The practical differences between flash eprom and eeprom though are now
disappearing,
so much so that it appears the that the term "Flash" no longer reliably refer
to the silicon technology.

Today, with low voltage eproms and in built programming algorithms you may
not even
know exactly what you have "Flash eprom" or "eeprom." It may not matter and it
appears that the functionality of memory now has little  to do whether is
it one
or the other technology. The in-built state machines in modern memory
effectively
provides the same programming algorithms based around embedded chip
identifiers and
programming parameters.

However, a few facts to point out the historical differences.

Microchip repeatedly said that it did not have "flash" technology and would
not
contract for an outside source to make its PICs in flash. Later microchip
simply renamed eeprom to flash though it was not "flash" at all.

Intel once made eeprom memory chips but quit them as a line and instead went
to "flash" eprom saying the eeprom had failed to become the cheap high density
nonvolatile memory that flash was.

Not all manufacturers are calling "eeprom" "flash." Some are, some aren't.
Clearly there has been a difference historically between "flash" and "eeprom."
The footprints are still in the sand if you want to research further and
discover when and how "eeprom" became "flash."

Sorry if this is all confusing. I really do not have a great way with words. I
think I'll stick to code from now on.

>I'm unaware if there are any patents or trademarks associated with it, I've
>never seen any notices remarking such is the case.
>
>Flash appears to be the generic term for any EEPROM which can be 'flash'
erased.

BTW. Why isn't anyone calling the 24C, 25C 93C eeproms - "flash?"

-Jim

{Quote hidden}

Regards,

Jim Robertson
NEWFOUND ELECTRONICS
Email: newfoundspamspam_OUTpipeline.com.au
http://www.new-elect.com
MPLAB compatible PIC programmers.

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2000\09\26@075233 by Andrew Kunz

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Wasn't FLASH an Intel TM at one point?  As I understood it, they didn't enforce
the tm and so lost it, but it was an intentional move which they wanted to use
to hype their memory technologies.

Andy










Jim Robertson <@spam@newfoundKILLspamspamPIPELINE.COM.AU> on 09/25/2000 11:15:42 PM

Please respond to pic microcontroller discussion list <KILLspamPICLISTKILLspamspamMITVMA.MIT.EDU>








To:      RemoveMEPICLISTTakeThisOuTspamMITVMA.MIT.EDU

cc:      (bcc: Andrew Kunz/TDI_NOTES)



Subject: Re: [PIC]: Flash vs. EEPROM








At 12:02 PM 25/09/00 -0400, you wrote:
>Flash memory is the same as eeprom except flash can be erased in blocks or
all
>at once, instead of a byte at a time.

This is not what "flash" was. Flash was a variation on EPROM technology not
EEPROM. Essentially flash replaced the UV erasure with an electrical erase
mode so eproms started to look more like eeproms. Semantically of coarse flash
eprom is eeprom but we are dealing with history and the conventions used to
delineate between the two technologies.

The practical differences between flash eprom and eeprom though are now
disappearing,
so much so that it appears the that the term "Flash" no longer reliably refer
to the silicon technology.

Today, with low voltage eproms and in built programming algorithms you may
not even
know exactly what you have "Flash eprom" or "eeprom." It may not matter and it
appears that the functionality of memory now has little  to do whether is
it one
or the other technology. The in-built state machines in modern memory
effectively
provides the same programming algorithms based around embedded chip
identifiers and
programming parameters.

However, a few facts to point out the historical differences.

Microchip repeatedly said that it did not have "flash" technology and would
not
contract for an outside source to make its PICs in flash. Later microchip
simply renamed eeprom to flash though it was not "flash" at all.

Intel once made eeprom memory chips but quit them as a line and instead went
to "flash" eprom saying the eeprom had failed to become the cheap high density
nonvolatile memory that flash was.

Not all manufacturers are calling "eeprom" "flash." Some are, some aren't.
Clearly there has been a difference historically between "flash" and "eeprom."
The footprints are still in the sand if you want to research further and
discover when and how "eeprom" became "flash."

Sorry if this is all confusing. I really do not have a great way with words. I
think I'll stick to code from now on.

>I'm unaware if there are any patents or trademarks associated with it, I've
>never seen any notices remarking such is the case.
>
>Flash appears to be the generic term for any EEPROM which can be 'flash'
erased.

BTW. Why isn't anyone calling the 24C, 25C 93C eeproms - "flash?"

-Jim

{Quote hidden}

Regards,

Jim Robertson
NEWFOUND ELECTRONICS
Email: TakeThisOuTnewfoundEraseMEspamspam_OUTpipeline.com.au
http://www.new-elect.com
MPLAB compatible PIC programmers.

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2000\09\26@085831 by M. Adam Davis

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Can you issue a block erase command to them?

-Adam

Jim Robertson wrote:
> BTW. Why isn't anyone calling the 24C, 25C 93C eeproms - "flash?"

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2000\09\26@163816 by Andy Howard

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>< From: "Jim Robertson" <RemoveMEnewfoundspamTakeThisOuTPIPELINE.COM.AU>
To: <PICLISTEraseMEspam.....MITVMA.MIT.EDU>
Sent: Tuesday, September 26, 2000 4:15 AM
Subject: Re: [PIC]: Flash vs. EEPROM



> BTW. Why isn't anyone calling the 24C, 25C 93C eeproms - "flash?"


Atmel seem to know the difference, they list both Serial EEPROM memory and
Serial FLASH devices.

The EEPROMs are in sizes <= 1MBit and Flash starts at 1MBit up to 32MBit.
Flash devices are available in page sizes from 256 to 1024 bits.












.

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2000\09\26@175715 by Patrick Magee

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On Tue, 26 Sep 2000, Andy Howard wrote:

> >< From: "Jim Robertson" <EraseMEnewfoundspamPIPELINE.COM.AU>
> To: <RemoveMEPICLISTEraseMEspamEraseMEMITVMA.MIT.EDU>
> Sent: Tuesday, September 26, 2000 4:15 AM
> Subject: Re: [PIC]: Flash vs. EEPROM
>
>
>
> > BTW. Why isn't anyone calling the 24C, 25C 93C eeproms - "flash?"
>
>
> Atmel seem to know the difference, they list both Serial EEPROM memory and
> Serial FLASH devices.
>
> The EEPROMs are in sizes <= 1MBit and Flash starts at 1MBit up to 32MBit.
> Flash devices are available in page sizes from 256 to 1024 bits.
>
I believe the difference is really in the access. EEPROM can be rewritten
on an individual location basis whereas FLASH must be erased a block at a
time. This makes FLASH less acceptable for data storage.

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2000\09\27@021058 by Nigel Goodwin

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In message <04d301c027f8$ce5abe40$c06d883e@oemcomputer>, Andy Howard
<RemoveMEmusicaspam_OUTspamKILLspamUKONLINE.CO.UK> writes
>>< From: "Jim Robertson" <RemoveMEnewfoundTakeThisOuTspamspamPIPELINE.COM.AU>
>To: <EraseMEPICLISTspamspamspamBeGoneMITVMA.MIT.EDU>
>Sent: Tuesday, September 26, 2000 4:15 AM
>Subject: Re: [PIC]: Flash vs. EEPROM
>
>
>
>> BTW. Why isn't anyone calling the 24C, 25C 93C eeproms - "flash?"
>
>
>Atmel seem to know the difference, they list both Serial EEPROM memory and
>Serial FLASH devices.

Don't Atmel list the AVR processors as 'Flash' when they actually use
EEPROM technology?.

>The EEPROMs are in sizes <= 1MBit and Flash starts at 1MBit up to 32MBit.
>Flash devices are available in page sizes from 256 to 1024 bits.

Is that the main difference between Flash and EEPROM, Flash is used for
large chips, and EEPROM for small?.
--

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2000\09\27@135426 by Andy Howard

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From: "Nigel Goodwin" <spamBeGonenigelgSTOPspamspamEraseMELPILSLEY.CO.UK>
> <KILLspammusicaspamBeGonespamUKONLINE.CO.UK> writes
> >>< From: "Jim Robertson" <EraseMEnewfoundspamEraseMEPIPELINE.COM.AU>

> >> BTW. Why isn't anyone calling the 24C, 25C 93C eeproms - "flash?"
> >Atmel seem to know the difference, they list both Serial EEPROM memory
and
> >Serial FLASH devices.

> Don't Atmel list the AVR processors as 'Flash' when they actually use
> EEPROM technology?.

I'm not sure, I don't use their processors, but their serial memory does
seem to be correctly identified.

> >The EEPROMs are in sizes <= 1MBit and Flash starts at 1MBit up to 32MBit.
> >Flash devices are available in page sizes from 256 to 1024 bits.
>
> Is that the main difference between Flash and EEPROM, Flash is used for
> large chips, and EEPROM for small?.

No, no. That was your free bonus information. Comparison shopping etc. I'm
pretty sure the main visible difference is as JimR and others mentioned, in
EEPROM bits may be individually erased, in Flash erasure is done a page at a
time. I believe this is due to Flash's roots in EPROM technology where an
entire chip is erased at once.
Time was when EEPROM was unbeliveably expensive for any significant size of
storage and Flash seemed like a useable compromise between function and
cost.

The difference in size ranges is no doubt due to likely use, for a small
data storage element you wouldn't want to have to erase large chunks of of
the device every time a small amount of data changed, hence flash may be
more suitable for bulk data applications.









.

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2000\09\28@051416 by Marc

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> Don't Atmel list the AVR processors as 'Flash' when they actually use
> EEPROM technology?.

No.  You're mixing it up with Microchip.

:-)

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2000\09\28@131907 by Nigel Goodwin

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In message <.....39D22EBD.504BCAC3spam_OUTspamaargh.franken.de>, Marc
<TakeThisOuTmarc.....spamTakeThisOuTAARGH.FRANKEN.DE> writes
>> Don't Atmel list the AVR processors as 'Flash' when they actually use
>> EEPROM technology?.
>
>No.  You're mixing it up with Microchip.

No, I know MicroChip did this, but I was under the impression that they
did so to respond to Atmel (and others) doing so in the first place?.
Following what has been discussed here recently, I wonder how much
supposed 'Flash' is actually really EEPROM - and does it matter?.
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2000\09\30@060556 by Marc

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> >> Don't Atmel list the AVR processors as 'Flash' when they actually use
> >> EEPROM technology?.
> >
> >No.  You're mixing it up with Microchip.
>
> No, I know MicroChip did this, but I was under the impression that they
> did so to respond to Atmel (and others) doing so in the first place?.
> Following what has been discussed here recently, I wonder how much
> supposed 'Flash' is actually really EEPROM - and does it matter?.

I think that they did it in response to all the other manufacturers
(including Atmel) offering FLASH controllers.  They didn't want to
change their technology, but renamed it because it is "sufficiently"
similar and makes up a better marketing term.

To me it doesn't matter, because I rarely use PICs.  A key advantage
of large flash arrays is that they not only allow bulk erasing but
also bulk programming.  During development, where I don't need Verify,
I can reprogram a 128kb ATmega103 (>90% full) in about 30 seconds.
On the other hand I frequently read on this list that an 8kb PIC16F87x
needs 2 minutes or more.

I don't claim that this is an inherent feature of FLASH versus EEPROM,
but appearently the real-world implementations exhibit this behaviour.

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2000\09\30@120057 by Robert Rolf

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Marc wrote:
> To me it doesn't matter, because I rarely use PICs.  A key advantage
> of large flash arrays is that they not only allow bulk erasing but
> also bulk programming.  During development, where I don't need Verify,

HUH? How do you 'bulk' program a device? Do you mean 'gang program'
(many at once). Gang programming is a function of a programmers
capabilities. There is no reason a PIC cannot be gang programmed
and separately verified. (There was a thread on this topic some
months back).


> I can reprogram a 128kb ATmega103 (>90% full) in about 30 seconds.
> On the other hand I frequently read on this list that an 8kb PIC16F87x
> needs 2 minutes or more.

The is more a function of the brain dead programmers Microchip supplies,
than the PIC architecture. 8K at 10ms/cell is only 82 seconds.
Why the ICD programmer takes 80ms/cell is beyond comprehension.

One thing people may be forgetting is that they can set a programming
address range, so that only the code that changes needs to be
programmed. I frequently  put in a org statement that isolates the
code being developed from the 'known good' code. That way I only
reprogram the stuff that's getting 'fixed' rather than the whole
code block. And with Microship's crappy programmer firmware, that's
essential.

E.G. If you set a programing range and check ONLY 'program memory',
the software uses that range. If you also have 'EEPROM Data'
checked the ICD will program the ENTIRE 8k bank, then the EEPROM data.
Similar problem if you make the mistake of having PM & 'Config bits'
set.
Is it really that hard to write code that's intelligent enough to
realize that the config register is but ONE cell, and program it alone
without messing with the program range?

> I don't claim that this is an inherent feature of FLASH versus EEPROM,
> but appearently the real-world implementations exhibit this behaviour.

It isn't. It's the TOOLS that cause this waste of time.

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'[PIC]: Flash vs. EEPROM'
2000\10\01@200843 by Jim Robertson
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At 11:57 AM 30/09/00 +0000, you wrote:
>> >> Don't Atmel list the AVR processors as 'Flash' when they actually use
>> >> EEPROM technology?.
>> >
>> >No.  You're mixing it up with Microchip.
>>
>> No, I know MicroChip did this, but I was under the impression that they
>> did so to respond to Atmel (and others) doing so in the first place?.
>> Following what has been discussed here recently, I wonder how much
>> supposed 'Flash' is actually really EEPROM - and does it matter?.
>
>I think that they did it in response to all the other manufacturers
>(including Atmel) offering FLASH controllers.  They didn't want to
>change their technology, but renamed it because it is "sufficiently"
>similar and makes up a better marketing term.

Just like ATMEL did. Microchip used this as part of their "defence"
as posted on the piclist when they rebadged EEPROM to Flash.

>
>To me it doesn't matter, because I rarely use PICs.  A key advantage
>of large flash arrays is that they not only allow bulk erasing but
>also bulk programming.  During development, where I don't need Verify,
>I can reprogram a 128kb ATmega103 (>90% full) in about 30 seconds.
>On the other hand I frequently read on this list that an 8kb PIC16F87x
>needs 2 minutes or more.

This is entirely sulfureous. The ATmega103 is EEPROM the same as the
16F87x.

>I don't claim that this is an inherent feature of FLASH versus EEPROM,
>but appearently the real-world implementations exhibit this behaviour.

ATMEL parts program quicker than microchip because Atmel parts have
data polling while microchip are stuck with rather conserative,
fixed, programming times. Newer Atmel parts also have a page
buffer and the 16kb ATmega163 can program in 1.3 seconds but it is
still EEPROM.



Regards,

Jim Robertson
NEWFOUND ELECTRONICS
Email: RemoveMEnewfoundspamspamBeGonepipeline.com.au
http://www.new-elect.com
MPLAB compatible PIC programmers.

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2000\10\01@202117 by David VanHorn

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>
> >To me it doesn't matter, because I rarely use PICs.  A key advantage
> >of large flash arrays is that they not only allow bulk erasing but
> >also bulk programming.  During development, where I don't need Verify,
> >I can reprogram a 128kb ATmega103 (>90% full) in about 30 seconds.
> >On the other hand I frequently read on this list that an 8kb PIC16F87x
> >needs 2 minutes or more.
>
>This is entirely sulfureous. The ATmega103 is EEPROM the same as the
>16F87x.


Sulfureous?

I recently had to reprogram some F876s, (using picstart) and my comment at
the time was "I'll never complain about the programming speed on my 8535's
again!"

The programmer I'm using now on the AVRs is a lot slower than the one I
used to use.. Never clocked it, but a very noticable difference.

I guess it's mostly in the programming algorithm.

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2000\10\02@074642 by Marc

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> HUH? How do you 'bulk' program a device? Do you mean 'gang program'
> (many at once).

No I meant that data is uploaded into SRAM page buffers and later the
complete page is programmed at once (taking little or nothing longer
than a single byte program on EEPROM).  This effectively reduces the
programming time of a single chip, for example in case of the ATmega103
to about 30 seconds (~110kb without verify).

Except for the 8 byte pages in some 24Cxx devices I have never seen
"EEPROM" chips feature this.  "FLASH" on the other hand usually has
this ability when a chip program would take too long without.

> E.G. If you set a programing range

I'd wish that a programmer skips empty memory locations during program
but reads them back during verify.  I can't understand why manufacturers
of programmers (not only Microchip) don't default to this setup.

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2000\10\02@084130 by Kevin Blain

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I'm not sure exactly what the difference is either, but

Why does the PIC 16F87x data sheet have fifferent endurance figures for the
"flash" part of memory than for the "eeprom" part?

the data sheet quotes on page 157::

Ep typical 1000 (flash endurance)
Ed typical 100 000 (eeprom endurance)

looks to me like different technology.......

regards, Kevin

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2000\10\02@085545 by Bob Ammerman

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The endurance limit on any sort of EEPROM/FLASH cell is strongly affected by
the geometry of the cell. I think that generally larger cells have better
endurance. So, the data and program 'flash' in the 87x are probably the same
technology, but microchip was willing/able to sacrifice more chip area to
get good endurance out of the data area.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

{Original Message removed}

2000\10\02@092025 by Bane Jakovljevic

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> I'm not sure exactly what the difference is either, but
>
> Why does the PIC 16F87x data sheet have fifferent endurance
> figures for the
> "flash" part of memory than for the "eeprom" part?
>
> the data sheet quotes on page 157::
>
> Ep typical 1000 (flash endurance)
> Ed typical 100 000 (eeprom endurance)
>
> looks to me like different technology.......
>
> regards, Kevin

One thing to note about the program memory is that Microchip deliberately
relax the spec of 1000x endurance, compared to other manufacturers. So this
should be taken conservatively when making comparisons. This was pointed out
at a recent Microchip seminar.
However, there was no discussion about Flash vs. EEPROM at the seminar...

Regards, Bane Jakovljevic

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2000\10\02@210623 by Jim Robertson

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At 07:21 PM 01/10/00 -0500, you wrote:
>>
>> >To me it doesn't matter, because I rarely use PICs.  A key advantage
>> >of large flash arrays is that they not only allow bulk erasing but
>> >also bulk programming.  During development, where I don't need Verify,
>> >I can reprogram a 128kb ATmega103 (>90% full) in about 30 seconds.
>> >On the other hand I frequently read on this list that an 8kb PIC16F87x
>> >needs 2 minutes or more.
>>
>>This is entirely sulfureous. The ATmega103 is EEPROM the same as the
>>16F87x.
>
>
>Sulfureous?

Yes, well in the context of the argument of the flash Vs EEPROM because
the ATMEL part is EEPROM like the 16F87x.

However this issue of programming time is not sulfureous as an
engineering or production matter. That fact that I have a patch
for the picstart plus to shorten the programming time of the
16F87x flash substantially shows I understand this. ;-)

I would never use a picstart plus to program the 16F87x parts
without my own driver and patched firmware, plug, plug. ;-)


>I recently had to reprogram some F876s, (using picstart) and my comment at
>the time was "I'll never complain about the programming speed on my 8535's
>again!"

Wait for the 8555s, you will love them for there programming speed. They
have a 32 byte write buffer (Plus 8x8 signed and unsigned multiply and
code protect options that allow protected areas to be software programmed
etc, etc.)

>
>The programmer I'm using now on the AVRs is a lot slower than the one I
>used to use.. Never clocked it, but a very noticable difference.
>
>I guess it's mostly in the programming algorithm.

Could be. Data polled Vs Minimum safe program time but the conservative
nature of microchip is also an issue. I believe the Microchip EEPROM
programs as fast as the ATMEL it is just that microchip allow a much
larger margin for safety. ATMEL as we know, can over rate things a little
(Remember the 16MHz micros that became 12MHz.)

-Jim

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Regards,

Jim Robertson
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2000\10\02@210631 by Jim Robertson

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At 01:35 PM 02/10/00 +0100, you wrote:
>I'm not sure exactly what the difference is either, but
>
>Why does the PIC 16F87x data sheet have fifferent endurance figures for the
>"flash" part of memory than for the "eeprom" part?
>
>the data sheet quotes on page 157::
>
>Ep typical 1000 (flash endurance)
>Ed typical 100 000 (eeprom endurance)
>
>looks to me like different technology.......
>
>regards, Kevin

Hi Kevin,

It is more expensive to make the higher endurance EEPROM. Microchip is
simply optimising the write cycle endurance of there EEPROMs cells
according to the likely write cycle requirements. Both the "Flash" and
"Data EEPROM" are EEPROM. Have a look at the programming specs for
the 16C84 and 16F84 and both the "Flash" and "Data EEPROM." Notice
any difference? There is none because it is ALL EEPROM.

-Jim

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2000\10\03@043406 by staff

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>
> Hi Kevin,
>
> It is more expensive to make the higher endurance EEPROM. Microchip is
> simply optimising the write cycle endurance of there EEPROMs cells
> according to the likely write cycle requirements. Both the "Flash" and
> "Data EEPROM" are EEPROM. Have a look at the programming specs for
> the 16C84 and 16F84 and both the "Flash" and "Data EEPROM." Notice
> any difference? There is none because it is ALL EEPROM.
>
> -Jim
>


Jim, are you saying that you can probably reprogram a 16F877 x 1 million
times? Actually, lets make that a 16C84 x 1 million times for the sake
of my sanity. But seriously, do you really think this is right??
-Roman

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2000\10\03@054653 by Martin Hill

picon face
No,
  I believe he is saying that they are the same TYPE of memory, but
the data section is optimised for more read / write cycles.  Hence
the same programming spec, but different endurance.  There is no
real need for 1M programming cycles on program memory, but 10k
would be a bit limiting on data memory.

Martin
{Quote hidden}

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2000\10\03@064937 by Jim Robertson

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At 07:12 PM 03/10/00 +1000, you wrote:
>>
>> Hi Kevin,
>>
>> It is more expensive to make the higher endurance EEPROM. Microchip is
>> simply optimising the write cycle endurance of there EEPROMs cells
>> according to the likely write cycle requirements. Both the "Flash" and
>> "Data EEPROM" are EEPROM. Have a look at the programming specs for
>> the 16C84 and 16F84 and both the "Flash" and "Data EEPROM." Notice
>> any difference? There is none because it is ALL EEPROM.
>>
>> -Jim
>>
>
>
>Jim, are you saying that you can probably reprogram a 16F877 x 1 million
>times?

Where on earth did you get that idea? All I said was that microchip
put the high endurance/larger celled/more expensive eeprom cells where it is
needed (in the data EEPROM) and not where it is not needed (Program memory.)

They then call one Flash and the other EEPROM when it is all EEPROM
even if it is of different endurance.

-Jim



Actually, lets make that a 16C84 x 1 million times for the sake
>of my sanity. But seriously, do you really think this is right??
>-Roman
>
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Regards,

Jim Robertson
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2000\10\03@131107 by Alice Campbell

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> No,
>    I believe he is saying that they are the same TYPE of memory, but
> the data section is optimised for more read / write cycles.  Hence
> the same programming spec, but different endurance.  There is no
> real need for 1M programming cycles on program memory, but 10k
> would be a bit limiting on data memory.
>
> Martin

err, ummm, i believe some of the dead bugs in my dead bug box
are there because i (re)programmed them to death.  after all,
at 3 minutes for a try-modify-burn cycle, thats only (!) 500
hours per pic.  the IDE lets me cut half a minute off that,
so thats less than 500 hours on a f877.

alice

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2000\10\04@043321 by Martin Hill

picon face
No offence intended, but if you are developing code and spending
500 hours doing try-modify-burn cycles, is this some sort of
software engineering by guesswork? :-)

Martin
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2000\10\04@043531 by Alan B. Pearce

face picon face
>err, ummm, i believe some of the dead bugs in my dead bug box
>are there because i (re)programmed them to death.  after all,
>at 3 minutes for a try-modify-burn cycle, thats only (!) 500
>hours per pic.  the IDE lets me cut half a minute off that,
>so thats less than 500 hours on a f877.

Yes but that is for the program memory which does have a lower number of reprogram cycles life. The data EEPROM portion is specified to many more times reprogram cycles life. Check the data sheet, they are specified differently.

Coming back to the Flash Vs EEPROM debate, I think this is the area that is used to distinguish between the two names now.
Flash as a terminology is used for the chips or area which have a low number of programming cycles available, and is used for storing program code.
EEPROM as a terminology is used for storage that has a high reprogram cycle life and is used for storing data.

These may not be the way the two terminology's started out, but it is the way they now tend to be used (from my observation), irrespective of trademarks and patents.

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2000\10\04@095813 by Arthur Brown

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A place I worked at took the chips from R&D on a Fiday or Saturday and put
them on the Prodution Line.
So the R&D team always had Fresh Chip to play with! I wonderd why we had a
lot of rework jobs on Wedensday afternoon?

Regards Art

{Original Message removed}

2000\10\05@055658 by Marc

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> ATMEL parts program quicker than microchip because Atmel parts have
> data polling while microchip are stuck with rather conserative,
> fixed, programming times.

Data polling is not implemented for the FLASH code memory. At least not
in the serial programming mode, which is the one I am reffering to because
it is most similar to what PICs offer.

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2000\10\05@090737 by Jim Robertson

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At 11:54 AM 05/10/00 +0000, you wrote:
>> ATMEL parts program quicker than microchip because Atmel parts have
>> data polling while microchip are stuck with rather conserative,
>> fixed, programming times.
>
>Data polling is not implemented for the FLASH code memory. At least not
>in the serial programming mode, which is the one I am reffering to because
>it is most similar to what PICs offer.

Actually, it is implemented for the FLASH code memory. Why you say otherwise
I don't know.

From every ATMEL AVR data sheet I looked at.

"Data Polling Flash
When a byte is being programmed into the Flash, reading the address
location being programmed will give the value $FF.
At the time the device is ready for a new byte, the programmed value will
read correctly. This is used to determine when the
next byte can be written. This will not work for the value $FF, so when
programming this value, the user will have to wait for
at least t WD_PROG before programming the next byte. As a chip-erased
device contains $FF in all locations, programming of
addresses that are meant to contain $FF, can be skipped."


Also, the ATMEL "flash" has a less conservative min programming cycle time
than microchip specify. As I have previously pointed out on the piclist the
program cycle time on the picstart plus can be halved for the 16F87x
parts. (I have done it and will be offering the patched firmware with my own
picstart plus driver.)

The variation in programming times between atmel and microchip "flash"
micros can also be seen in different manufacturers of serial EEPROMs.
Therefore it is as moot to hold up programming times as proof of a flash
technology (as in not EEPROM) as it is to hold up endurance figures of Flash
program space Vs data EEPROM.

Both atmel and microchip micros are EEPROM in both the program and data
memory.  Selectively rebadging the program memory as "flash" doesn't
change this even if the practise is so wide spread as to replace the
older meaning of the term "Flash" (Which it appears it has in some
quarters but not others.)


-Jim


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Regards,

Jim Robertson
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