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Your computer's BIOS is not typically backed up. I'll look at why, and whether you should be concerned about backwards compatibility when upgrading it.

Ever since I got my computer with Win 7 Pro in Dec 09, I've been faithfully backing up and making system images with the built-in Backup and Restore feature. When I got my laptop it had BIOS version A04 installed by the factory. I've since upgraded to version A08 based on a recommendation by the built-in Dell diagnostics utility. On the Dell support website (drivers and downloads) version A08 is the only listed BIOS for the Vostro 1520.

If I understand things correctly (not always the case!) the BIOS resides as flash software within the CPU which is on the motherboard. It's the BIOS that kick-starts the operating system. If the BIOS becomes corrupted or fails, your computer becomes a paperweight. During a backup, system image, or creating a restore point, only the hard drive is copied. The BIOS is NOT included. I can verify this if I use the Dell Recovery Manager and return my computer to factory settings or use one of my earlier system images. All of the junkware returns, but the BIOS still shows as A08 at startup.

When a person updates his/her BIOS, will it be backwards compatible? In other words, if a computer experiences issues and the BIOS is updated as part of the corrective action, and then the computer has to be returned to it's original factory state, or to an earlier system image, will the newest BIOS always be compatible? If there's a chance the BIOS will not be compatible how does one make a backup of the earlier BIOS(es) if they're no longer supported or available at the Dell website?

You have a very good understanding of what a BIOS is, where it lives and how it's not backed up. In fact, I feel like you've written half my article for me. Smile

But you also raise a very important question about backwards compatibility. I'll address that, and clarify a couple of the items you mention.

The BIOS doesn't really reside "within" the CPU, rather it's typically a separate chip on the motherboard. The difference is perhaps a technical one, but what's important is that the BIOS is not stored on your hard disk or, for that matter, related to your operating system in any practical way.

"Almost by definition BIOS updates ... must always be backwards compatible."

The most important point is that the BIOS is not backed up by backup software.

There are many reasons for this, perhaps the most common is the practicality of a backup program restoring it. While there's certainly a standard - perhaps one of the oldest PC standards - about reading the BIOS there's no standard way to write to it. Backup programs might be able to save a copy of the BIOS, but if you ever needed that copy they wouldn't really know what to do with it.

Add to that the fact that the BIOS is typically somewhat complex to write to, and the result is that it rarely needs to be "recovered" in the same sense that data on your hard drive might need to be.

Bottom line: backing up a BIOS isn't really all that necessary or useful.

The only way I really know to backup BIOS would be to download the BIOS update utility from your computer manufacturer that corresponds to the version of the BIOS you have in your machine. If you ever need to re-flash it, you'd have that utility to do so.

The days of a corrupt or failed BIOS turning a computer into a paperweight are, fortunately, pretty much behind us. Most motherboards have some way to reset the BIOS to some initial state or version - often with a jumper or connector you physically move on the board. Once the original factory-default BIOS has been put into place, you can then typically use the downloaded update utility to then take it to a more current version.

Almost by definition BIOS updates, when installed on the motherboards that they are intended to support, must always be backwards compatible. I've not heard of a case where they're not.

There is a theoretical problem if some random software relies on a bug in the BIOS that is subsequently corrected, but that's extremely rare, and in most cases fixing the BIOS issue are more important than a badly behaved application.

In general, however, you should feel safe updating a BIOS, as long as you're doing so with the correct version for your specific motherboard.

Article C4348 - June 20, 2010 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

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14 Comments
Duane
June 22, 2010 5:22 AM

"Flashing the BIOS" is not really all that difficult. These days, manufacturers offer BIOS updates as a download, and they come with very specific instructions. I've done a few BIOS updates, and have only ever run in to problems on one occasion. The computer gave a specific warning that I was about to install an incorrect BIOS update, and that I had best stop. I did. Disaster averted. If your BIOS ever became corrupted, you'd have little trouble getting the correct update on to a flash drive, and resolving the issue by following the instructions provided.

Randy Mitchell
June 22, 2010 6:43 AM

The article was very informative. I always thought that when you did a complete backup that the BIOS was included in the backup.

jack mccurdy
June 22, 2010 6:52 AM

Although bad bios flashes are much more rare than they used to be, they can still occur. One thing you should never attempt, to fix a poor running computer, by flashing your bios. If your system isn't stable, that is when you will likely experience a bios flash gone bad. especially with a Windows based flashing tool. which is what most manufacturers offer these days, and if your bios flash has left your system un bootable, the Windows based flashing tool will not work obviously. If you read some help forums, you will see a lot of people still having problems, usually because they didn't know what they were doing, and tried to fix stability issues by flashing their bios.

Bob Batchelder
June 22, 2010 7:28 AM

I'd like to add a quick comment about backup. One of the first things I do with any new system is to create a folder on drive C called "Upgrades". Then whenever I download software, drivers or in the case of this example, a BIOS Flash Utility, it too will have a folder under "Upgrades". If a downloaded software product has a license key, I put a word document in the folder with the key and date of expiration. This whole folder ("Upgrades") is part of my backup scheme. It keeps me well organized and I no longer lose this important information.

Zippy Rhyme
June 22, 2010 8:10 AM

There are always older versions available on the Dell website for BIOS and other driver updates, that are posted. For the Vostro 1520, you can check the link below:

http://tinyurl.com/vos1520

These are the older versions of the BIOS for your model. However, it is not 'recommended' to downgrade the BIOS unless it is specifically suggested or if you are facing serious issues after updating the BIOS.

Sandy Coulter
June 22, 2010 8:22 AM

Dear Leo,

Just a couple of important points that were missed. If you do not have a battery backup for your computer and there is a power failure or surge during the flashing process of the BIOS, the motherboard can be rendered completely useless. I do not recommend flashing the BIOS of any device unless there is a valid reason for doing it. If nothing is wrong, don't fix it just because there is a newer version.

Also, there is a difference between the CMOS and the BIOS although the terms are often used interchangeably. The BIOS on the motherboard contains the instructions on how the computer boots and is only modified or updated with BIOS updates (as in flashing the BIOS), the CMOS is powered by the CMOS battery and contains your system settings and is modified by entering the CMOS Setup. There were tools that could backup the CMOS settings a few years back, but in this day and age of motherboards with reset jumpers, why bother?

I would like to know more about the jumper that restores the BIOS. The only jumper I am aware of simply restores the CMOS setting. If your BIOS firmware is blown away, there is no fixing that without a BIOS chip transplant, or replacement of the motherboard.

Feel free to write me to discuss the topic...I have a few horror stories to share. --Sandy Coulter

JH
June 22, 2010 9:04 AM

@Sandy
Yes, the majority of computers nowadays only reset the CMOS, which does nothing if a flash has gone wrong, although if you accidentally set a setting wrong resetting the CMOS will fix it (although the only setting I can really think of that would do this would be the clocks, and most of the motherboards used by OEM's won't allow you to fiddle these anyway)

Many enthusiast motherboards nowadays, however, have dual BIOS's, so if the flash goes wrong it will not brick the computer, and others will automatically flash from a flash drive even if the BIOS is broken, but such tech generally does not filter down to the 'average' user. The only reason I have had to flash my BIOS is to allow Win7 to run (it was unstable before).

Ed Vance
June 23, 2010 8:25 AM

Leo,

I have always known the term CMOS to be an abbreviation for "Complementary Metal Oxide Semiconductor"

Which is the material that the Early BIOS Integrated Circuit (IC) chips were made of.

The XP box I am using now shows the title "Phoenix Award BIOS CMOS" when I go to the BIOS Setup on it.

This BIOS can be upgraded by Flashing it.

I don't know if these current Flash BIOS chips are made of the same CMOS substance or not.

The older BIOS's couldn't be Flashed.

I think way back then You would have to unplug the older BIOS IC from its socket and replace it with an newer, updated version of the BIOS.

That is, if the BIOS chip wasn't soldered onto the Motherboard.

I've never upgraded the BIOS on my old 1994 486 computer.

The Battery on it has died so I just set the Date and Time when ever I turn that box on so I can use it. ;-)

SalemCat
June 24, 2010 9:58 AM

The Complementary metal–oxide–semiconductor (CMOS) is the actual, physical chip on the motherboard, or hardware.

The BIOS is purely code, or software.

The CMOS can be fine, but have corrupted BIOS programmed into it. But the BIOS will never be fine if it is on a faulty or dead CMOS chip (obviously).

Although these terms are often used interchangeably (even by me) they are different.

SalemCat
June 24, 2010 10:08 AM

If you think of the CMOS as a Hard Drive, and the BIOS as a Software Program, you'll always understand the fine distinction betwen the two.

Bruce Chandler
July 17, 2010 8:55 PM

Hello, I am wondering if a bios that is live update will get rid of a virus in my bios... I have zeroed out the drives but I cannot get rid of the boot sector write virus. Do I need to flash the bios or will a liveupdate bios fix itself? This is my school and personal pc and it has got to be fixed like yesterday, please if you can help me let me know. I have tried all I usually have to but I cant get this one to go away and there is no bios flash for my MSI motherboard only live update...the motherboard is rs482m4... Thank you.

I'm not sure that I know what "live update" means as you're using it. It could mean many things. Typically if a BIOS is infected then you need to reflash it with a clean copy. However it's very rare that a BIOS actually has a virus, so I would absolutely make sure that's what you're facing first.
Leo
18-Jul-2010

alex cage
October 28, 2010 10:38 AM

How exactly is a bios refalashed 9with a clean copy)?

Typically you download a utility from the motherboard or computer manufacturer which includes instructions on how. It varies from manufacturer to manufacturer, but most place a small program on a floppy, CD or USB device, and then reboot from that where the program runs and performs the operation.
Leo
28-Oct-2010

alex cage
October 28, 2010 10:39 AM

sorry for the typo, I mean how do we reflash BIOS?

Rusty Shack
March 16, 2012 9:55 PM

Your articles show SOME level of technical competence, and an ability to explain things in plain English, but you're no guru (and neither am I, and I can still tell).

1. Your article about the lack of security of BIOS passwords failed to note that one can take the CMOS battery out and wait for any capacitors to discharge.

2. There are certainly situations where a BIOS backup/restore would be handy. Imagine a laptop which gets a BIOS update that changes the language from English to, say, Japanese. An English speaker who doesn't read Japanese would want to restore it, probably. Access to the motherboard would be problematic.

And that's from reading just 2 articles.

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