View Full Version : Accessing Bios Settings 386SX-20

15-02-2002, 08:15 AM
I have been trying to reinstall operating system etc back onto a 386 PC.

At start up I played with the CMOS settings (BIos version 1.52 - Arche Technology and altered some of the settings.

Now I cannot get back to the bios settings as the PC just does memory test and stops.

Usually you enter delete to access bios settings.

I thought that you could rest CMOS but I could not see a battery on the motherboard.

Can someone help? Many thanks

15-02-2002, 09:43 AM
It could have a jumper that says reset CMOS written on the m/b, so you will need to jump that switch.

15-02-2002, 10:44 AM
386s generally didn't have a removable battery or a CMOS reset jumper - thus making it quite difficult to reset your BIOS if you've done something silly.

I'm not familiar with the BIOS you've mentioned, but you could try hitting DEL repeatedly from BEFORE the memory test begins, and maybe it'll let you into the setup.

Otherwise it may require an unsoldering of the battery (its usually soldered on somewhere near the keyboard plug), leaving it for a few hours, and soldering it back on, and maybe that'll reset the BIOS. I wouldn't suggest this unless you know what you're doing with a soldering iron.

15-02-2002, 11:32 AM
Some motherboards were fitted with Dallas clocks that had their own internal battery. When these failed the board was thrown away. The batteries were supposed to last up to 10 years....

As Mike says, if there is a soldered on battery and its gone down, remove it before it leaks all over the board. The best way is to snip it off with side cutters, that way the board wont be damaged. Its very difficult to unsolder through plated holes and boards have several layers too.

Many boards had a plug for an external battery, and a jumper to set.
The cheapest way to make up an external battery is to use a CR2032 cell in a holder canabalised from a junked PCI m/b.

However after all that it doesnt quite sound like a battery problem, as one would have expected some sort of CMOS error message.
Depending on how intelligent the bios is, changing something, like the amount of memory, or disconnect the floppy drive, may cause the machine to go into bios setup.
There are also lots of other key combos to try other than DEL to get into bios.


15-02-2002, 03:11 PM
One way which works for some computers is to unplug the keyboard, and powering up. If the BIOS is set up right, it will complain about the missing keyboard, and *some* of them give you the option of pressing F1 (or something) to get into the setup. You can then plug the keyboard in, and press F1 or whatever.

But even before doing this, try unplugging everything from the I/O slots. (except the video card). Even remove the memory, unless it is in 18 pin DIPs. Try again to get into the setup.

If there is a half-matchbox sized black block with the 'Dallas' brand, that is a unit with an internal battery.
Look at the board near that unit for a pair of pins labeled 'RST' or something like that. If you find one, try shorting the pins for a while (with power off). If you do that with the power off you are unlikely to damage anything. Of course if smoke starts to rise ...

15-02-2002, 03:14 PM
Thanks for your advices Mike. Before I stuffed up access to be bios I had reloaded MS DOS 6 after reformated the harddrive. This was due to the fact that a message came up. No operating system and I tried various things (such as installing MS DOS 6.) I could boot up with floppy disk but the Pc would not recognise that it had an operating system.

Are you able to shed any light on this - is it likely to be software or hardware problem (maybe the motherboard is stuffed - it is an old PC at the end of the day but had been working okay - its my brothers PC).

Many thanks