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View Full Version : CMOS battery causing 286 not to boot from HDD?



twistedpneumatic
October 28th, 2017, 08:25 AM
I have a Pentium 100 machine that recognizes the HDD correctly but will not boot from it if the CMOS battery is dead. This has happened twice due to those damn Dallas RTC-battery chips. My 286 Magnavox Laptop is experiencing the same thing, where 3rd party programs that address the controller directly(SpeedStor) recognize the drive fine, but when FDISK tries it, or the BIOS, they both fail to find it/boot from it respectively. Could the CMOS battery be causing this 286 to not boot from the HDD?

Chuck(G)
October 28th, 2017, 10:14 AM
Sure--the BIOS goes to the CMOS/Clock memory to find out what kind of disk that you have installed. If that's bollixed, the BIOS will conclude that you have no hard disk.

modem7
October 28th, 2017, 03:09 PM
... This has happened twice due to those damn Dallas RTC-battery chips. ... Could the CMOS battery be causing this 286 to not boot from the HDD?
It is natural to think, "Surely, if the CMOS battery (whether external, or part of a CMOS module) goes low, all that will happen is that the CMOS settings/clock will be lost when the motherboard is powered off." Posts to these forums reveal that there can be other symptoms. Example at [here (http://www.vcfed.org/forum/showthread.php?41716)].

twistedpneumatic
October 29th, 2017, 09:01 AM
Oh crap, its a Dallas:mad: RTC soldered to the board :mad: !!