Adding the CR2032 seems like a fairly fun and not too difficult hack. I have 2 old 386s that need the treatment. At least the Dallas RTC doesn't spew acid all over the motherboard when it croaks.

I definitely prefer the Dallas bricks, those batteries run forever while onboard solutions run the battery dry pretty quickly when the machine sees little use.

TheMobRules wrote:

root42 wrote:

Couldn’t the Dallas be replaced by some custom circuitry? Did anyone ever reverse engineer them? I mean it’s „only“ an RTC. How hard can it be.

DS12887 drop-in replacement

+1

Plus you get the fun of doing a little soldering.

I got 5 PCBs printed. If i ever get round to assembling them I'll sell the other 4. Then all you need to do is replace a cr1220 instead of a 20 quid chip whos age is shrouded in the mists of time.

Vaudane wrote:

+1 […]
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TheMobRules wrote:

root42 wrote:

Couldn’t the Dallas be replaced by some custom circuitry? Did anyone ever reverse engineer them? I mean it’s „only“ an RTC. How hard can it be.

DS12887 drop-in replacement

+1

Plus you get the fun of doing a little soldering.

I got 5 PCBs printed. If i ever get round to assembling them I'll sell the other 4. Then all you need to do is replace a cr1220 instead of a 20 quid chip whos age is shrouded in the mists of time.

I still have a small mountain of them, unfortunately I found out shipping from here to just about anywhere would be basically as expensive as the module itself ($15-$20 shipping) so it's really not worth it. 😠 Good luck assembling them and/or sharing the CAD files! It's not difficult to assemble if you have a vaguely steady hand and a remotely decent soldering iron.

Got my Acer 386 today, and from the looks of it, the Dallas chip is actually already mounted in a socket. That's almost too good to be true. From the looks of this system so far, it is really well built. I want to check the PSU before I try plugging it in to test it.

root42 wrote:

Wow. This looks... interesting. Remind me never to buy a board with a Dallas RTC...

Me too, but unfortunately my 486 motherboard already has it. I have no idea how to change it or make it socketed.

Atom Ant wrote:

root42 wrote:

Wow. This looks... interesting. Remind me never to buy a board with a Dallas RTC...

Me too, but unfortunately my 486 motherboard already has it. I have no idea how to change it or make it socketed.

Desolder the old RTC, solder in a DIP socket, buy a newly manufactured Dallas replacement chip from Maxim Integrated on Digikey for $10.

I found a Texas Instruments BQ3287AMT-SB2, which according to the datasheet is a drop-in replacement for the DS1287 series. They sold for $4.49 on eBay, and if the photo is genuine, it should be from 2017, which suggests many years of computing.
I could get Maxim branded DS12887A+ here in Norway, but the price was about 2.5 times the price of the Ti model on eBay, so I'll just have to be patient and wait for the slow delivery from Hong Kong.