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Win 95 era BIOS boot error

moon_man157

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May 10, 2022
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I've got an 1996 era desktop that I'd like to get up and running. It will POST but shows a CMOS battery low error and press f1 to resume. It has one of those pesky Dallas clock chips so I really hope that's not the issue because I really don't want to mess with changing it just yet. I've set the BIOS to boot from floppy first but the POST just stops cold on this error message and from what I can tell the floppy never even tries to seek. I've tried changing a bunch of settings in the BIOS but had no luck. I'm using a Win95 set up disk. I'd really appreciate any help you guys can provide.20220509_200410.jpg20220509_200440.jpg20220509_200452.jpg20220509_200443.jpg
 
Some motherboards refuse to save bios settings without a working bios battery. Most likely the case here. Grab a 2032 coin cell and slap it into the motherboard, then setup bios and should work correctly. I do not see any other error messages so should be good to go.
 
Some motherboards refuse to save bios settings without a working bios battery. Most likely the case here. Grab a 2032 coin cell and slap it into the motherboard, then setup bios and should work correctly. I do not see any other error messages so should be good to go.
Thanks for the reply, I wish this computer did use a coin cell battery because I've got a load of those sitting around. Sadly this uses a Dallas clock chip which is soldered to the motherboard. I'm aware that there are mods to attach a coin cell battery in its place but all this requires a lot of disassembly and soldering. I'd rather not do that until I'm sure the computer will be otherwise functional. Does anyone have any other ideas?
 
+1 for twolazy. Don't worry about the Dallas clock at this time. You need to address the system battery first thing.
 
I was under the impression that a Dallas clock chip has a self-contained battery and clock crystal all in one package. Since these chips are always soldered directly to the motherboard is necessary to completely unsolder the Dallas chip and attach a new one to effectively change the battery. I thoroughly checked the motherboard and do not see a coin cell battery anywhere. Maybe I'm just not looking for the right thing. Here are some pictures.20220509_222401.jpg20220509_222405.jpg20220509_222418.jpg20220509_222430.jpg
 
-1 for twolazy and -1 for Agent Orange

We've traced the CMOS/RTC battery, it's coming from inside the Dallas chip.
 
Yes, if there is a Dallas chip on the board, and it's about 2 - 3 times taller than a regular IC, then you can be pretty sure it's got an integrated battery.

You have 1 of 3 options for this.

1. Buy a new old stock park, desolder it and put the "new" one in.
2. Desolder it, and do the coin cell mod on it, effectively disconnecting the internal battery and routing the pins to a coin cell holder you glue on the outside Here's how to do it.
3. Desolder the old Dallas and replace it with one of these: https://www.tindie.com/products/glitchwrks/gw-12887-1-ds12887-rtc-replacement-module/

Personally, I'd go with #3, but no matter what option you go with, don't re-solder it to the board, instead buy a socket and solder that to the board and insert the replacement/hacked chip.
 
Thats the first ever socket 7 board I have seen, with no coin cell battery. Why would they have used a Dallas chip? Strange...
 
Maybe using up old stock. I've got an Acer Pentium with a socketed Dallas chip.
 
1. Buy a new old stock park, desolder it and put the "new" one in.
Not speaking as a hobbyist but within my professional job please never do this. Repeatedly I've been bitten by customers who bought NOS clock modules, only for the new module to fail within three months to a year. Sometimes it's a swap-out and a CMOS reprogram, other times it's a call to the license vendor because your keys vanished in a power drop.
You have no history of how they were stored and even then they've had their clocks ticking as soon as the batteries were soldered in. Either rebuild it, buy a substitute or pay for a brand new module. Never trust NOS modules.
 
Personally, if this were my board, I'd do the battery transplant without desoldering the RTC chip. It can be done--I've done it. I use a Foredom variable-speed handset with a small burr bit to do the deed. A Dremel isn't nearly as versatile--which is probably why dentists still use handsets and not Dremels.
 
Personally, if this were my board, I'd do the battery transplant without desoldering the RTC chip. It can be done--I've done it. I use a Foredom variable-speed handset with a small burr bit to do the deed. A Dremel isn't nearly as versatile--which is probably why dentists still use handsets and not Dremels.
You can get flexible hand set extensions about a metre long for Dremel type tools. My wife has one for her hobby work.
 
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