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'Serial SRAM'
1998\01\27@072856 by Justin Grimm

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Hi
Has anyone had any experience in using serial SRAM and the pic74?   
Im building a project that requires about 2k x 8 RAM and I need nearly
all of my I/O.
Thanks
reaper@southwest.com.au
 

1998\01\27@085234 by mike

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In message  <01bd2b1d$ee49c5a0$24d31ecb@desktop> spam_OUTPICLISTTakeThisOuTspamMITVMA.MIT.EDU writes:
>
> Hi
> Has anyone had any experience in using serial SRAM and the pic74?   =20
> Im building a project that requires about 2k x 8 RAM and I need nearly
> all of my I/O.
> Thanks
> .....reaperKILLspamspam@spam@southwest.com.au

Reaper,

In the past I would have recommended serial FRAM for your application.

However, I have had some difficulty getting hold of parts recently, so
would advise caution before designing them into a product.

Regards,

Mike Watson
--
Denison Mayes Group

1998\01\27@131440 by Harold Hallikainen

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On Tue, 27 Jan 1998 20:20:18 +0800 Justin Grimm <reaperspamKILLspamSOUTHWEST.COM.AU>
writes:


>Has anyone had any experience in using serial SRAM and the pic74?
>=20
>Im building a project that requires about 2k x 8 RAM and I need nearly
>all of my I/O.

       Let me know if you find one!  I finally ended up using the Dallas
RamPort in several projects.

Harold

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1998\01\27@194525 by Pat Reitelbach

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Solutions Cubed has a pcba providing this function.  About $30.
See their product line at http://www.dcs-chico.com/~solcubed/


At 01:12 PM 1/27/98 EST, you wrote:
{Quote hidden}


'Serial SRAM'
1998\12\04@144230 by Andy Kunz
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I recall (but didn't save it, of course <G>) a thread a while back about
serial SRAM.

I'm looking for a serial SRAM part which will store, say, 2KB of data.  My
own research shows up FLASH and EEPROM, but due to the large number of
rewrites and the speed I need it perform, neither technology will suffice.

Naturally, low power (Li battery backup) would be ideal.

Thanks.

Andy

OH yes, mandatory political comment to generate responses.  "I think Bill
Gates is the best thing for the computer industry."

HACK COUGH <G>

==================================================================
Andy Kunz - Statistical Research, Inc. - Westfield, New Jersey USA
==================================================================

1998\12\04@174034 by David W. Duley

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In a message dated 12/4/98 11:42:40 AM Pacific Standard Time,
EraseMEmtdesignspam_OUTspamTakeThisOuTFAST.NET writes:

<< I recall (but didn't save it, of course <G>) a thread a while back about
serial SRAM.

I'm looking for a serial SRAM part which will store, say, 2KB of data.  My
own research shows up FLASH and EEPROM, but due to the large number of
rewrites and the speed I need it perform, neither technology will suffice.

Naturally, low power (Li battery backup) would be ideal.

Thanks.

Andy

OH yes, mandatory political comment to generate responses.  "I think Bill
Gates is the best thing for the computer industry."

HACK COUGH <G>
 >>

Hi Andy!
Philips makes some smaller than 2K I2C serial RAM.  I think they are 256
bytes.  You can address up to eight of them together.
The other thing that I have seen is a serial Ram module.  I saw it on the
Parallax site.
Also there is FRAM by ramtron.  These act like the old core memory.  They are
good for several billion reads and writes.  They are pin compatable with the
Microchip 24 and 25 series serial eeproms.

Dave Duley

1998\12\04@203704 by Peter Grey

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Have you considered FRAM. I hear the chip density has just been increased.
Data is available at RAMTRON.com.

good luck,


Peter Grey
At 01:59 PM 4/12/98 -0500, you wrote:
{Quote hidden}

1998\12\04@214228 by John Hansen

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At 12:34 PM 12/5/98 +1100, you wrote:
>Have you considered FRAM. I hear the chip density has just been increased.
>Data is available at RAMTRON.com.
>
>good luck,
>
>
>Peter Grey

Interesting product.  Anyone have any idea what these cost?

John Hansen

1998\12\04@223905 by Peter Grey

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At 09:38 PM 4/12/98 -0500, you wrote:

In Australia for 512x8 it is A$2.56(1 off) & A$2.13(1000 off); for 2kx8 it
is A$4.99 & A$3.76


Regards,

Peter Grey

{Quote hidden}

1998\12\05@083141 by nanthan Paramananthan

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Hi Peter,

I'm also interested in very large Serial SRAM.
Could you please give me the name of the Australian Supplier?

Thank you.

regards
Saba


{Original Message removed}

1998\12\05@100132 by wwl

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On Fri, 4 Dec 1998 17:39:38 EST, you wrote:

>In a message dated 12/4/98 11:42:40 AM Pacific Standard Time,
>mtdesignspamspam_OUTFAST.NET writes:
>
><< I recall (but didn't save it, of course <G>) a thread a while back about
> serial SRAM.
>
> I'm looking for a serial SRAM part which will store, say, 2KB of data.  My
> own research shows up FLASH and EEPROM, but due to the large number of
> rewrites and the speed I need it perform, neither technology will suffice.
>
How many rewrites ?  How fast ? How many at a time?
Remember that Microchip guarantee 1 million cycles on their EE's, and
some devices have high endurance 10million cycle blocks.
Most have write caches to allow writes of up to 8-64 (depending on
part) bytes at a time.

1998\12\05@100547 by wwl

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On Sat, 5 Dec 1998 12:21:50 -0000, you wrote:

>Hi Peter,
>
>I'm also interested in very large Serial SRAM.
>Could you please give me the name of the Australian Supplier?
>
>Thank you.
>
>regards
>Saba
Dallas do a chip that provides a serial interface & backup for  a
parallel SRAM chip.

1998\12\05@102026 by Peter L. Peres

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On Sat, 5 Dec 1998, Mike Harrison wrote:

> How many rewrites ?  How fast ? How many at a time?
> Remember that Microchip guarantee 1 million cycles on their EE's, and
> some devices have high endurance 10million cycle blocks.
> Most have write caches to allow writes of up to 8-64 (depending on
> part) bytes at a time.

How about getting the relevant pdf. docs and reading about all that from
http://www.ramtron.com/ ?

One thing I did not know is, that FRAM also has a limited read cycle
count. I haven't gotten around to read all this yet, however.

Peter

1998\12\05@164616 by paulb

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Hello Peter.

> One thing I did not know is, that FRAM also has a limited read cycle
> count. I haven't gotten around to read all this yet, however.

 It's very simple.  It's miniature "core" memory.  Reads are performed
as writes with sense lines.  Therefore read endurance = write endurance.
--
 Cheers,
       Paul B.

1998\12\05@220203 by Andy Kunz

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>Philips makes some smaller than 2K I2C serial RAM.  I think they are 256
>bytes.  You can address up to eight of them together.

Too much board space, Dave.

>The other thing that I have seen is a serial Ram module.  I saw it on the
>Parallax site.

I'll have to check that out.

>Also there is FRAM by ramtron.  These act like the old core memory.  They are
>good for several billion reads and writes.  They are pin compatable with the
>Microchip 24 and 25 series serial eeproms.

If you can get them.  I've only managed samples and outrageous lead tiems.
They must be made by Mot <G>

ANdy


==================================================================
 Andy Kunz - Montana Design - http://www.users.fast.net/~montana
==================================================================

1998\12\06@114718 by Peter L. Peres

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On Sun, 6 Dec 1998, Paul B. Webster VK2BZC wrote:

> Hello Peter.
>
> > One thing I did not know is, that FRAM also has a limited read cycle
> > count. I haven't gotten around to read all this yet, however.
>
>   It's very simple.  It's miniature "core" memory.  Reads are performed
> as writes with sense lines.  Therefore read endurance = write endurance.

If so, then why does it have a lifetime at all (on a human scale) ?! Last
time I checked the core memories from way back are in tip top condition to
this day and will probably outlast any silicon structure given the same
packaging and environmental care. The only thing that dies in a core
memory is the line driver/read amplifier, and only if improperly designed.

Even data retention is not a problem. Just use EDC in the storage and
rewrite the array with correction every 2 years or so. ;)

?
Peter

1998\12\06@115959 by paulb

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Peter L. Peres wrote:

>>> One thing I did not know is, that FRAM also has a limited read cycle
>>> count.
>>   It's very simple.  It's miniature "core" memory.  Reads are
>> performed as writes with sense lines.

> If so, then why does it have a lifetime at all (on a human scale) ?!

 Don't ask me!  It seems to be related to why EEPROM has a lifetime.
Doing funny things repeatedly to a microscopic structure appears to let
bits leak out (literally - as molecules/ atoms).  It pushes too hard.
Don't ask me!
--
 Cheers,
       Paul B.

1998\12\06@121634 by John Hansen

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At 05:57 PM 12/6/98 +0000, you wrote:
>
>If so, then why does it have a lifetime at all (on a human scale) ?!

For most applications it may not.   According to the docs you should be able to
write to each memory location once each second continuously for 317 years.
(That's 10 billion operations).

I just wish I could find a place to buy one-ses of these in the U.S.

John Hansen

1998\12\07@023421 by David W. Duley

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In a message dated 12/5/98 7:02:25 PM Pacific Standard Time, @spam@mtdesignKILLspamspamFAST.NET
writes:

<<
If you can get them.  I've only managed samples and outrageous lead tiems.
They must be made by Mot <G>

ANdy
 >>
Hi Andy
I hear you here.  I hear Motorolla just announced that they were discontinuing
almost all of their 68705 cpus and several 6811 derivatives.  The 68705 is a
sucky cpu anyway but it will send alot of people running for somthing new that
have been using these things for years.

The Frams have been around for a number of years.  I wonder why they havent
more of a following than they do?

The parallax thing is by Soulution Cubed and is a 8K X 8 module that is spoken
to serially. It lookes like it is logic level standard rs232 type serial.
Kinda large though.

Dave Duley

1998\12\08@110323 by Peter L. Peres

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On Mon, 7 Dec 1998, David W. Duley wrote:

> The parallax thing is by Soulution Cubed and is a 8K X 8 module that is spoken
> to serially. It lookes like it is logic level standard rs232 type serial.
> Kinda large though.

jameco carries a 32kbyte seeram using a PIC and a sram apparently, as a
5-pin (?) module. The price is in the star-spangled skies imho.

Peter

1998\12\08@120202 by Tom Handley

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  Dave, Motorola is still pushing a lot of 6805-based cores for dedicated
applications. Though I love the 68HC11 it probably takes a few decades
to get production quantities unless you make cars and trucks...

  FRAMs, in my humble opinion, have failed to gain general acceptance due
to their price, their inability to provide production quantities, and the
advances in FLASH technology. Despite earlier comments, FRAMs have absolutely
no resemblance to magnetic core memory of long ago. They used ferrite rings
with a couple of select wires and a sense wire.

  - Tom

At 02:33 AM 12/7/98 EST, Dave Duley wrote:
{Quote hidden}

1998\12\08@125114 by juha tuomi

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>>Hi Andy
>>I hear you here.  I hear Motorolla just announced that they were
discontinuing
>>almost all of their 68705 cpus and several 6811 derivatives.  The 68705 is
a
>>sucky cpu anyway but it will send alot of people running for somthing new
that
>>have been using these things for years.

>>Dave Duley



Where did you hear this from?  I am using 68HC705C8A in a few applications
and get worried...  I checked Motorola websites and there was not a mention
about discontinuing. Will call my distributor and ask.

Juha Tuomi
Finland

1998\12\08@133317 by Harold Hallikainen

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       I'm thinking of just using a couple 8 bit serial in parallel out
shift registers to drive address (and maybe control lines) of the SRAM,
and using 8 bits of I/O on the PIC.  Serializing the address lines could
save a lot of pins.  Tristating the data lines could allow them to be
used for some other purposes (reading switches through resistors or
something like that).
       A serial SRAM would sure be nice!  EDN ran a special section on
SRAMs in a recent edition, but did not mention serial SRAMs.  I wrote the
author.  He replied that he thought the die size of a large SRAM (say 32
Kbyte) was too large to fit in a small package (like maybe 8 pin DIP), so
they needed the larger package and just used the pins that came with the
larger package.  I don't really mind the larger pacakge, I just don't
want to use all my PIC pins!


Harold




Harold Hallikainen
RemoveMEharoldTakeThisOuTspamhallikainen.com
Hallikainen & Friends, Inc.
See the FCC Rules at http://hallikainen.com/FccRules and comments filed
in LPFM proceeding at http://hallikainen.com/lpfm


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1998\12\08@142137 by Peter L. Peres

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On Tue, 8 Dec 1998, Harold Hallikainen wrote:

>         I'm thinking of just using a couple 8 bit serial in parallel out
> shift registers to drive address (and maybe control lines) of the SRAM,
> and using 8 bits of I/O on the PIC.  Serializing the address lines could
> save a lot of pins.  Tristating the data lines could allow them to be
> used for some other purposes (reading switches through resistors or
> something like that).

Actually using a CMOS counter will be faster (1..2 x 4040) but makes
jumping backwards complicated (long live caches and structured
programming w/o subroutines).

I have used a combination of these on occasion (high 14 addresses from
4040, low 4 direct from micro).

It is possible to use a serializer for the data too, but it makes it very
slow and CPU-intensive. I think that a PIC 64 is what is needed. It can be
used to address a large device and still have pins left. (I used such a
PIC for similar purposes). The C64 has enough oomph to drive even a 32
MB SIMM with some time left over, and some pins left over.

I might also mention that a HCT373 or two can be used to reduce the data
and address IO pin count to 8 using 8031-style ALE-latching. Only 1 strobe
pin is required (the latch devices are in series and supply addresses only
to the target SRAM). Addressing is pretty fast under the circumstances.

If one uses 'Ohm' type gates <G> on the memory D I/O then only 2 wires are
required to control the device with up to 64k x 8 and this is in range for
a F84. One control wire supplies the strobe pulses to the address latches,
and also drives the CS of the RAM (to allow bus muxing if req'd), the
second is wired directly to ~WE on the RAM.

2 IO pins remain free for general use (serial ?).

hope this helps,

Peter

1998\12\08@150644 by Zonn

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On Tue, 8 Dec 1998 19:49:22 +0200, juha tuomi <spamBeGonejuha.tuomispamBeGonespamliperi.fi> wrote:

>>>Hi Andy
>>>I hear you here.  I hear Motorolla just announced that they were
>discontinuing
>>>almost all of their 68705 cpus and several 6811 derivatives.  The 68705 is
>a
>>>sucky cpu anyway but it will send alot of people running for somthing new
>that
>>>have been using these things for years.
>
>>>Dave Duley
>
>
>
>Where did you hear this from?  I am using 68HC705C8A in a few applications
>and get worried...  I checked Motorola websites and there was not a mention
>about discontinuing. Will call my distributor and ask.

While I was finishing up a project using the 68HC05C0, Motorola announced to its
users that they plan on discontinuing most of the 6805 line.

It seemed only those products that were sold in the millions would be continued.
We were assured that our product would be one of those.  Unfortunately, I don't
have a list of affected processors.

Two months later we were told that the 68HC05C0 would be discontinued (throwing
away two years of work and a few million in investment dollars).  After
discussions between Motorola, and the head of the company I'm contracting for,
it was agreed that the 68HC05C0 would be continued.  But this most likely
because the product I'm working on (a remote control for cable boxes) will be
sold in the millions -- and that the company I'm working for is also very
closely associated with another company that uses in upwards of 10's of millions
of Motorola 6805 parts per year (also remote controls).

If you're currently using a 6805 family part (especially if you're in the design
phase) I suggest you check with Motorola to see if they plan on continuing the
part.  Their first response will be "Yes of course" (They can't help it, they're
Motorola).  Try them again a month later -- if you can reach them, once again
this Motorola were talking about.

And who knows, by now there might be a whole change of plan, and the 6805 might
be their "New Part into the New Millennium!", doubtful, but this *IS* Motorola!

-Zonn

<><><><><><><><><><><><><><><><><><><><><><><><><><><><

------              ___       Member of A.A.C.S.:
|---- |            (   )  Association for Artistically
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  / /    //\\ //   (__)
 / ---/ //  \\    //\\ //      zonn @ zonn . com
-------|         //  \\/

1998\12\09@035626 by juha tuomi

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Thanks, Zonn

Regards,
Juha


-----Original Message-----
From: Zonn <TakeThisOuTzonnEraseMEspamspam_OUTZONN.COM>
To: RemoveMEPICLISTspamTakeThisOuTMITVMA.MIT.EDU <PICLISTEraseMEspam.....MITVMA.MIT.EDU>
Date: 8. joulukuuta 1998 22:07
Subject: Re: Serial SRAM



While I was finishing up a project using the 68HC05C0, Motorola announced to
its
users that they plan on discontinuing most of the 6805 line.



And who knows, by now there might be a whole change of plan, and the 6805
might
be their "New Part into the New Millennium!", doubtful, but this *IS*
Motorola!

-Zonn

1998\12\10@131209 by Gerhard Fiedler

picon face
At 13:59 12/04/98 -0500, you wrote:
>I'm looking for a serial SRAM part which will store, say, 2KB of data.  My
>own research shows up FLASH and EEPROM, but due to the large number of
>rewrites and the speed I need it perform, neither technology will suffice.
>
>Naturally, low power (Li battery backup) would be ideal.

did you find any yet? if 400kHz access speed is enough (write operations at
bus speed), you might have a look at the http://www.ramtron.com fram devices. no
battery backup needed, it seems. (i don't know them, just stumbled over the
info somewhere.)

ge

1998\12\10@140053 by Andy Kunz

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At 10:01 AM 12/10/98 -0800, you wrote:
>At 13:59 12/04/98 -0500, you wrote:
>>I'm looking for a serial SRAM part which will store, say, 2KB of data.  My
>>own research shows up FLASH and EEPROM, but due to the large number of
>>rewrites and the speed I need it perform, neither technology will suffice.
>>
>>Naturally, low power (Li battery backup) would be ideal.
>
>did you find any yet? if 400kHz access speed is enough (write operations at
>bus speed), you might have a look at the http://www.ramtron.com fram devices. no
>battery backup needed, it seems. (i don't know them, just stumbled over the
>info somewhere.)

No, Gerhard, I haven't.

The best I can find so far (and "best" includes "can actually purchase in
20K volume") is the Phillips PCF8570.

Andy

==================================================================
Andy Kunz - Statistical Research, Inc. - Westfield, New Jersey USA
==================================================================

1998\12\10@141927 by Ohtsji, Randie

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What about Atmel's DataFlash (SPI interface)?  Datasheets on the Atmel
website (http://www.atmel.com).
I requested a sample kit from our local distributor and will meet with an
Atmel rep tomorrow.

Has anyone used these DataFlash parts?

Randie
EraseMErandie.ohtsjispamglenayre.com


> {Original Message removed}

1998\12\10@163624 by David W. Duley

picon face
In a message dated 12/10/98 11:01:12 AM Pacific Standard Time,
RemoveMEmtdesignEraseMEspamEraseMEFAST.NET writes:

<<
No, Gerhard, I haven't.

The best I can find so far (and "best" includes "can actually purchase in
20K volume") is the Phillips PCF8570.

Andy
 >>
Hi ANDY!
Since I am looking for somthing similar,  I found the Dallas DS2404.  It has
twice the ram as the Philips part and has a real time clock as well.  It will
work with the 1 wire protocol or a 3 wire protocol or both.  It also has a 48
bit unique serial number rom.
They are $3.89 in 1000 piece qty.

Dave Duley
Dreitek Inc.
http://www.dreitek.com

1998\12\10@165442 by William Chops Westfield

face picon face
This problem seems to be back.  In an 11.3AA image, I get a crash one minute
FOLLOWING the random telnet connection:


Program received signal SIGBUS, Bus error.
0x105284 in timer_running ()
(cisco-68k-gdb) bt
#0  0x105284 in timer_running ()
#1  0xe5618 in notify_state_change ()
#2  0x4640ce in xot_context_detach ()
#3  0x469bde in xot_timed_wakeup ()
#4  0x450bc8 in x25lib_task ()

For cs-x25:  make a telnet connection to a router configured for x25 routing,
and type quit<return>

BillW

1998\12\10@173257 by William Chops Westfield

face picon face
"oops"....

:-)
BillW

1998\12\11@081554 by Andy Kunz

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At 11:07 AM 12/10/98 -0800, you wrote:
>What about Atmel's DataFlash (SPI interface)?  Datasheets on the Atmel
>website (http://www.atmel.com).
>I requested a sample kit from our local distributor and will meet with an
>Atmel rep tomorrow.
>
>Has anyone used these DataFlash parts?

Yes, I have.  They work nice.

Problem is that they tend to take a while to burn, and I don't have that
much time to do it when the power is failing.

Andy


==================================================================
Andy Kunz - Statistical Research, Inc. - Westfield, New Jersey USA
==================================================================

1998\12\11@085959 by Andy Kunz

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face
>Since I am looking for somthing similar,  I found the Dallas DS2404.  It has

Thanks, Dave, I'll check it out.  My inside guy at Dallas didn't know about
it.

Andy

==================================================================
Andy Kunz - Statistical Research, Inc. - Westfield, New Jersey USA
==================================================================

1998\12\11@125424 by David W. Duley

picon face
In a message dated 12/11/98 6:00:08 AM Pacific Standard Time,
RemoveMEmtdesignspam_OUTspamKILLspamFAST.NET writes:

<< >Since I am looking for somthing similar,  I found the Dallas DS2404.  It
has

Thanks, Dave, I'll check it out.  My inside guy at Dallas didn't know about
it.

Andy
 >>
Hi Andy,
Dallas is pretty cool about small quantities.  They have online ordering for
items upto $250 or 10 pieces directly.  This is way cool if youv'e ever(and I
know you have) tried to get 5 parts out of anybody for evaluation.  I ordered
10 of the DS2404s yesterday.  They were in stock.
good luck
Dave Duley

1998\12\12@001358 by John Griessen

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I worked for Delco in Santa Barbara in 1988. THEY definitely had production
quantities of 68hc11's.  It was only a decade a ago...
maybe they have some to spare now....

JG

-----Original Message-----
From: pic microcontroller discussion list
[RemoveMEPICLISTTakeThisOuTspamspamMITVMA.MIT.EDU]On Behalf Of Tom Handley


  Dave, Motorola is still pushing a lot of 6805-based cores for dedicated
applications. Though I love the 68HC11 it probably takes a few decades
to get production quantities unless you make cars and trucks...

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