DS12887 pcb substitute with battery

allison ajp166 at verizon.net
Sun Jan 22 12:57:49 CST 2017

I don't know about most people but this solution has been around for

I locate the battery on the failed part with a small magnet, then grind the
epoxy down to it then pick it out with a sharp pointed tool.  Once I expose
the connection point I older two wires then epoxy a small coin-cell holder
in that spot and it s done.  I've done this more times than I care to count
and its effective and the replacement battery some over 10 years old
now have not failed.  But just in case I have a bag of NOS replacements
(and pulls from socketed boards) all with dead batteries from age.  There
is no magic to this.


On 01/22/2017 01:20 PM, Ali wrote:
> Jon,
> Then why not use a dip compatible version of the DS chip? I mean yes this allows for switchable battery which is very nice but SMT soldering is not for everyone.
> I wonder if there is a way to determine if there will be BIOS issues by switching the DS12887?
> -------- Original message --------
> From: Jon Elson <elson at pico-systems.com> 
> Date: 1/22/17  9:16 AM  (GMT-08:00) 
> To: General at classiccmp.org, "Discussion at classiccmp.org:On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> 
> Subject: Re: DS12887 pcb substitute with battery 
> On 01/22/2017 10:07 AM, Ali wrote:
>> Al,
>> I thought the problem with switching these chips was that part of the ROM code was embedded in them? I.e. it isn't just an issue of battery? Am I wrong? If I am then why not use one of the replacement chips that are available?
> These don't have a lot of memory on them.  many early PCs 
> stored some config info there, but generally the BIOS can 
> reconstruct it if it isn't there.  I suppose there is a 
> possibility that random data in the CMOS memory could cause 
> the BIOS to try to use unavailable features and hang.  I 
> don't think anybody put actual executable code in there.
> Jon

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