Been thinking the same lately, as my old Compaq Portable III probably has a dead ds1287. I was going to have a go at cutting into it and using a coin cell. The replacement ds chips I've seen seem pretty dear, and I couldn't tell how new they really were. The coin cell solves the problem for once and for all doesn't it?

rumbadumba wrote:

The coin cell solves the problem for once and for all doesn't it?

Yes, I believe it does. Replace the dead battery within the RTC epoxy block with a new [coin cell] one, and you remove the problem. Although I'd rather just replace the whole socketed RTC. I wonder where RTCs can be bought at affordable prices? And whether they'd be good for most, if not all 486 mobos?

A discussion about this issue can be found here -

http://www.vintage-computer.com/vcforum/showt … ighlight=Ds1287

I'm tempted to get one of these -

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewIt … e=STRK:MEWAX:IT

It's a DS12887 RTC, from an ebay seller in Hong Kong. The cost including shipping seems quite reasonable - about £9. The quantity in stock is nearly 100, and the seller has 100% positive feedback.

Having read some of those articles about hacking the ds1287, it seems it's not foolproof.

http://www.walshcomptech.com/ps2/dallasrework.html

The manufacturer's website incidentally makes it clear that you may not be able to use the ds1287 or it's successors to replace other chips.

http://www.maxim-ic.com/appnotes.cfm/an_pk/503

In my case, I found the Compaq didn't have a ds1287 anyway [at least not that I culd see] but a 1.5" square of plastic labelled "lithium battery". I shan't replace it unless/until I get a hard drive that the machine can recognise.