Dallas clock battery

[Scott Stevens]

On Thu, 29 Dec 2005 15:18:32 -0800
"Chuck Guzis" <cclist at sydex.com> wrote:

> On 12/29/2005 at 5:58 PM Scott Stevens wrote:
> 
> >The method for installing a battery on a Sun NVRAM module is well
> >established and can be searched.  I've done that one on numerous
> >occasions.  I think the Dallas chips are laid out entirely
> >differently.  Probably someone should dissect one with a dremel
> >tool and write a howto somewhere.  It is a worthwhile project.
> >The upper module is almost certainly sealed seperate from the
> >chip itself, if it's like the Sun-type modules, there are
> >contacts somewhere you can dremel in to and solder on an external
> >battery lead.
> 
> I can see where digging into the clock chip for a Sun might be worthwhile
> as replacements are hard to come by, but the DS1287 used in the Compaq (and
> a lot of PCs) is relatively inexpensive and readily available. It's robably
> not worth the trouble digging into the EDIP to find where to hook the
> battery up. 
> 

Some of us are just more stubborn and cheap (and whatnot else)
than others.  I like solutions that I know I will be able to use
for the next 25 years.  I don't know how long Dallas will
continue to make the DS1285.  And I have encountered motherboards
where the CMOS module is SOLDERED ON THE MOTHERBOARD (*yikes*).

> If an external battery is desired, you could just take a DS1285, which is
> essentially the 1287 without the battery and hook a coin cell between pin
> 20 and ground.  
> 

That makes sense.  Ideally the original module belongs 'tied with
string in a cloth bag within the housing' as was discussed here
awhile back, to preserve the authenticity of the original system.