Anyone have any experience replacing a Dallas 1287 with a 12887?

From: Lawrence Walker <>
Date: Tue Dec 31 23:19:01 2002

 A while back I had problems accessing a Grid 1520-286
because of a password. If I remember correctly it was a
DS1287A. The A signified it as resettable and grounding
2 pins cleared the memory. Your problem would seem to
stem more from the BIOS settings and it is going to the
default setting and since the Dallis chip is dead nothing
is retained. ISTR that the 12887 is a drop-in replacement.
If you want to call soldering all those pins "drop-in"

 Dallas has a bunch of info on the chip. I don't have the
URL handy.

Considering all the problems and low used prices
involved. You might consider getting an old Grid 1520
which also has the advantage of an additional EPROM
slot which can contain info configuring various aspects of
the computer, including a system boot.


On 31 Dec 2002, , Ethan Dicks wrote:

> While attempting to revive a Compaq 286/SLT laptop for use
> as a front-end for my UP600a programmer, I have found that
> the battery on the DS1287 has died (no suprise there). What
> sucks is that even after I run the floppy-based setup
> utility, after a reboot (not a power-off cycle), the machine
> forgets what I just set, both the data and time, and the
> geometry of the A: drive. Seeing as how it thinks there's a
> 5.25" floppy and it's really a 3.5" high-density drive at
> the end of the cable, as you can imagine, it won't reliably
> read disks.
> So... I have ordered a replacement DS12887 since they no
> longer make/ship the DS1287. Couple of interesting app
> notes here:
> What I'm wondering is if anyone on the list has ever
> replaced a DS1287 with a DS12887. One of the sheets seems
> to suggest that I'll need an updated BIOS ROM (clearly not
> available for a 286 laptop) to drive the extra stuff
> associated with the enhanced century rollover.
> Alternatively, has anyone here successfully performed
> surgery on a Dallas module? I have disconnected the battery
> from a Mostek 48T02 from a SPARC and soldered on an external
> Lithium cell, but the packaging makes it easy to get access
> to the battery wires coming down from the top (I even put
> the battery on a 9V battery snap so it's easier to replace)
> I haven't heard of anyone doing this for the more sealed
> Dallas modules.
> So... anybody else suffer though this?
> -ethan
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May you get halfway to heaven, before Satan learns you're
dead or 3/4s of the way to the bar before your wife finds
you've gone out.
Received on Tue Dec 31 2002 - 23:19:01 GMT

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