How did he know for sure it was a DS12887?

Generally DS128(8)7 modules tend to be interchangeable, but DS1387 (Realtime RAMified, i.e. RTC with 4k SRAM) are a different kind of beast. Boards with DS1387 don't boot without DS1387 in there and don't even begin to post with a DS128(8)7 in the socket. Possibly that's what's going on here...

An ebay listing for an identical board has a DS12887 (though not a DS12C887.. compatible chips?)

https://www.ebay.com/itm/Socket3-UMC-Expert-b … d-/323686508195

So?..

Apparently DS12C887 ought to work: http://pdf.datasheetcatalog.com/datasheet_pdf … or/DS12C887.pdf

DS12C887+ is just a lead-free DS12C887, so those are exactly the same. The DS12C887 adds a century byte to the DS12887 for Y2K support, according to the docs it should be fully compatible, but I don't know if any issues may arise due to that.

Maybe the replacement clock he got was also a dud? We will see..

I have the same board and it came with a DS12887. Replaced it with a DS12887+ and it's giving me a low battery error a well. It does however save my CMOS settings.

Any chance you can tell me the make and model of this board?

appiah4 wrote:

Any chance you can tell me the make and model of this board?

Sadly no. I could not get it to post when I found it as it would just give me 2 long beeps. Tried looking for a manual to id the issue, but after not being able to find it I assumed the dallas was dead. Replacing it got it to post, just with a low battery warning.

Well.. I did some digging, and the manual is here, if that helps you out any: http://www.elhvb.com/mobokive/Archive/Data%20 … 046/m-8046b.zip

appiah4 wrote:

Well.. I did some digging, and the manual is here, if that helps you out any: http://www.elhvb.com/mobokive/Archive/Data%20 … 046/m-8046b.zip

Thank you!
Has all the speed/voltage/cache settings listed and that's enough for me.