[vcf-midatlantic] Dallas TOD replacement (was: Feb 2017 workshop)

[VAXman at tmesis.org]

Herb Johnson via vcf-midatlantic writes: 

>There is a literal "mod" of Dallas chips: 
>
>http://www.retrotechnology.com/herbs_stuff/sgi_battery.html 
>
>wherein you slice into the epoxy package and splice in a watch battery.
>if this is the mod you are doing, I'd be glad to reference any Web page
>you have about doing it. 
>
>There are likely some old versions of the Dallas time-of-day chip and
>RAM which have no modern version. That said: 
>
>VAXman posted: 
>
>> The DS1287A was fairly common TOY clock back then.  You can replace it
>with > the newer DS12887A.  Goggle it, there are ample sources. 
>
>...one has to replace it with a compatible device, and it's a bit of
>work and luck to determine if any replacement is likely to work.
>Whereas, you have the chip-in-hand, that only has a dead battery. 

Well, the DS12887A has worked well for *all* of my VAX and or Alpha systems
that were equipped with the DS1287A.  That "slicing into the chip" hack to
add a battery has seen serveral re-incarnations over the years whenever the
topic of replacement arises.