How To:Reset the BIOS in an IBM PS/2

The BIOS in a PS/2 is maintained by the CMOS battery. When this battery fails the BIOS is lost and must be reset. Resetting the BIOS varies depending on the specific model though all models require a reference diskette to restore the BIOS, if your computer did not come with one, you can find them here: [1].

[top]How to identify the problem

If an IBM PS/2 shows error's 161 and 163 in POST then this guide should be used, if not and other error cods are seen please consult the forum here:[2]. Error 161 is a dead CMOS battery. Error 163 is called configuration error and usually occurs when the BIOS is reset from a dead battery. Usually the PS/2 will also show a message that looks like a crossed out ok with an arrow pointing to a stack of books.

[top]How do I repair the problem

This problem can be resolved in a number of ways, varying depending on the model. BEFORE you start the procedure below I recommend testing the diskette image from the website above to confirm that the disk image is correct and that the drive itself is operational (any mechanical device is prone to failure).
1:Download the reference disk on another computer, run the file and follow the on screen instructions to make a reference diskette for your specific PS/2.

2:Test the reference disk to confirm operation.

3:Open the computer (Take note of any removed screws/IC's), in most cases you will see a visible battery, in some cases however such as in a PS/2 model 55sx a Dallas clock module was used containing the battery. If the battery is visible, order a replacement and install in the computer. If you have a Dallas clock module see here: [3]

4:Once step 3 is completed, reassemble the computer being careful to note the placement of screws and any removed cards/semiconductors.

5:Start the computer, if step 3 was done correctly error 161 should no longer be present, though error 163 will appear.

6:Turn off the computer, place the reference diskette you created in step 1 in the drive of your PS/2.

7:Turn the computer on, this time error 161 will appear, but the computer will then load the BIOS off the disk.

8:The diskette should allow you to restore the BIOS, do so now.

9:Allow the computer to restart normally, your computer should if you followed the steps above boot into the Operating System on the disk (if present).


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