15 Aug
2006
15 Aug
'06
8:26 a.m.
Subject: Re: PDP-8 /e/f/m memory
From: "Chuck Guzis" <cclist at sydex.com>
Date: Mon, 14 Aug 2006 22:19:08 -0700
To: cctalk at classiccmp.org
On 8/14/2006 at 9:35 PM Don wrote:
I shave off the top of the DS1287s and replace the cell. It's easy to find
the battery on those as it's magnetic!
Unless you can make a battery application last A VERY LONG TIME
(not just a LONG time since those are the cases where you get
screwed because you have forgotten about the battery that
you replaced 1 or 2 years ago... *but*, if you replaced it
*10* years ago you don't mind -- as much -- when it dies
after that long of a service life) it will frustrate users.
Well, consider the Dallas battery-inside-the-chip clock-calendar circuits.
7 years sounded like forever--and it may well have been to the original
owners of the equipment. But now, they're starting to fade and finding
replacements can be a bit of a hassle. In 20 years, it'll probably be
nearly impossible. For this particular application, any keep-alive power
source needs only to
last as long the longest power-off interval. If, as Don, says a supercap
will last several months, that should be good enough--and it's a permanent
solution. Heck, I wonder if you could trickle-charge the battery with
ambient light via a solar cell. That should extend the keep-alive period
some.
I just don't like chemical reactions in my equipment--it's sort of like
bird's nest soup. It might taste good, but I don't like the idea of eating
bird spit..
Then place the battery at the ends of two wires remote from where their
failure can do harm.
Experience is a good adaquately sized Li cell is by far the easiest solution
when used with the Dallas ram controller chips.
Allison
15 Aug
15 Aug
12:33 p.m.
On Tuesday 15 August 2006 08:26 am, Allison wrote:
I shave off the top of the DS1287s and replace the
cell. It's easy to find
the battery on those as it's magnetic!
Interesting! What tooling do you use to do this?
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
1:22 p.m.
On Tue, 2006-08-15 at 12:33 -0400, Roy J. Tellason wrote:
On Tuesday 15 August 2006 08:26 am, Allison wrote:
Don't know about the original poster, but I plug them into a scrap
ethernet card, and carefully remove the epoxy with a grinder. Probably
a small dremel-type tool would be better than a 4" angle grinder, but I
haven't had any failures yet.
Gordon.
I shave off the top of the DS1287s and replace
the cell. It's easy to find
the battery on those as it's magnetic!
Interesting! What tooling do you use to do this? 
1:26 p.m.
From: "Roy J. Tellason" <rtellason at verizon.net>
I thought they were kinda sorta designed to make this easy? I seem to
recall
some of the Dallas parts even have available battery replacements, where you
can remove the old battery and attach the new, which snaps onto the IC
somehow?
Of course, given how part availability works these days, I'd expect to
retool
the snap-on carrier to allow me to put batteries elsewhere, as surely no-one
will
even admit to having heard of the things by the time you need the new
battery.
Vince
On Tuesday 15 August 2006 08:26 am, Allison wrote:
> I shave off the top of the DS1287s and replace the cell. It's easy to
find
the battery on
those as it's magnetic!
Interesting! What tooling do you use to do this? 
1:39 p.m.
vrs wrote:
From: "Roy J. Tellason" <rtellason at
verizon.net>
I thought they were kinda sorta designed to make this easy? I seem to
recall
some of the Dallas parts even have available battery replacements, where you
can remove the old battery and attach the new, which snaps onto the IC
somehow?
The Mostek (?) "top hat" package was designed like that.
Most of the Dallas parts I have seen were potted blocks.
On Tuesday 15 August 2006 08:26 am, Allison
wrote:
> I shave off the top of the DS1287s and replace the cell. It's easy to
find
the
battery on those as it's magnetic!
Interesting! What tooling do you use to do
this? 
3:46 p.m.
On Tue, 15 Aug 2006 12:33:20 -0400
"Roy J. Tellason" <rtellason at verizon.net> wrote:
Have a look
at the Sun NVRAM FAQ...
I shave off
the top of the DS1287s and replace the cell. It's easy
to find the battery on those as it's magnetic!
Interesting! What tooling do you use to do this?
I file down
the half of the molded top where the battery is until I
reach the + pole of the battery. I use the wire of the + pole as a guide
for the next step. I use some Dremel like tool to mill the side of the
molded top away until I can access the + and - pole / the wires coming
out of the chip. Then I disconnect only the + wire from the battery,
solder wires to the wires coming out of the lower part of the chip and
attach a new battery. Finaly I put some glue on the miled side of the
chip to support the new wires.
--
tsch??,
Jochen
Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/
5:08 p.m.
On 8/15/2006 at 9:46 PM Jochen Kunz wrote:
> > I shave off the top of the DS1287s and
replace the cell. It's easy
> > to find the battery on those as it's magnetic!
> Interesting!
Isn't there a non-battery version of these chips? That is, a regular old
DIP version with external leads for a battery?
Cheers,
Chuck
8:16 p.m.
On Tue, 15 Aug 2006, Allison wrote:
For anyone who's interested, here's a website with lots of pics on how to
do this:
http://www.giga.nl/computers/nvram/
I opted to epoxy a 2032 cell holder on top of the chip rather than run
wires out to an AA holder. The result is on the above site.
--
David Griffith
dgriffi at cs.csubak.edu
A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
Well, consider
the Dallas battery-inside-the-chip clock-calendar circuits.
7 years sounded like forever--and it may well have been to the original
owners of the equipment. But now, they're starting to fade and finding
replacements can be a bit of a hassle. In 20 years, it'll probably be
nearly impossible.
I shave off the top of the DS1287s and replace the cell. It's easy to find
the battery on those as it's magnetic!
6557
days inactive
6557
days old
7 comments
8 participants
participants (8)
-
ajp166＠bellatlantic.net -
cclist＠sydex.com -
dgriffi＠cs.csubak.edu -
gordon＠gjcp.net -
jkunz＠unixag-kl.fh-kl.de -
rtellason＠verizon.net -
THX1138＠dakotacom.net -
vrs＠msn.com