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'Memory devices'
1998\07\16@193958 by Jason Tuendemann

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Hi all,

I am looking at making a data logger which will require a lot of
non-volitile RAM about 256-512 kbytes (8bit byte) and preferrably serial.
Does any one have any suggestions?
Atmel have a chip which is serial 4 megabit which has 2048 pages of 264
bytes x 8 bits whick looks fine but because the pages are 264 bytes does
that mean that I have to write to it page at a time. In the data sheet it
decribes eraseing the page before writing to an address, so could I write 16
bytes to a page of 264 without eraseing the whole page?

Regards Jason.

1998\07\17@101447 by Matt Bonner

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Jason Tuendemann wrote:
> I am looking at making a data logger which will require a lot of
> non-volitile RAM about 256-512 kbytes (8bit byte) and preferrably serial.
> Does any one have any suggestions?
> Atmel have a chip which is serial 4 megabit which has 2048 pages of 264
> bytes x 8 bits whick looks fine but because the pages are 264 bytes does
> that mean that I have to write to it page at a time. In the data sheet it
> decribes eraseing the page before writing to an address, so could I write 16
> bytes to a page of 264 without eraseing the whole page?
>
I believe that you have to erase the whole page.  To get the density
that flash offers (as opposed to EEPROM), you lose some functionality.
Atmel also makes an 8Mbit part - AT45D081, although I don't know what
the availability is.  These look like great devices, but unfortunately
(for me) they don't come in mil-spec.

--Matt

1998\07\17@121341 by Mike Keitz

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On Fri, 17 Jul 1998 07:58:24 -0600 Matt Bonner <spam_OUTmbonnerTakeThisOuTspamSUNADA.COM>
writes:

>I believe that you have to erase the whole page.  To get the density
>that flash offers (as opposed to EEPROM), you lose some functionality.

True, you must write exactly 264 bytes to the Flash array at a time.  But
the chip has two 264-byte RAM buffers so it is possible to modify part of
a 264-byte page without having to move data out of the chip and back in
(read to RAM, change some bytes in RAM, write back to Flash).  I've just
looked over the data sheet and it looks like a nice part.  Strangely
though they don't mention anything about endurance.

> don't know what the availability is.

How available is the 4M part?  Has anyone bought one?

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1998\07\17@125820 by Sean Breheny

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I have used a flash chip from a company called MXIC (I think that it is
also sometimes called just MX). I think that the part number was
something like F4000. I is a 4Mbit FLASH chip. While it DOES require that
you erase in blocks, it didn't require writes to come in blocks. It is
very easy to use, and I think that AMD and maybe Atmel might make similar
parts. AFAIK, most flash chips allow single byte writes, its just erasing
that needs to be done block or whole chip at a time.

Sean


On Fri, 17 Jul 1998, Mike Keitz wrote:

{Quote hidden}

1998\07\17@132913 by Matt Bonner

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Sean Breheny wrote:
>
> AFAIK, most flash chips allow single byte writes, its just erasing
> that needs to be done block or whole chip at a time.
>
According to my various flash data sheets, that's correct.

--Matt

1998\07\18@102715 by Claudio Rachiele IW0DZG

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                  Status Distribution July 17, 1998 14:13:57

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