Working with your Computer’s BIOS – CompTIA A+ 220-801: 1.1

The BIOS is an important part of your computer’s configuration. In this video, you’ll learn about the PC BIOS and it’s importance to the startup process of your computer.

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When you start your computer, there’s a lot of hardware that’s very diverse, and yet it all needs to be able to communicate with each other. You’ve got keyboards and mice. You’ve got hard drives that need to operate. You need to have some way to see this information on the screen. You’ve probably got a CD-ROM or a DVD-ROM that needs to load information. There needs to be central place that stores the configuration and allows all of these different very diverse components to communicate with each other.

Your computer’s BIOS provides this functionality. This is the basic input/output system for your computer. This is the firmware that starts up whenever you power on your PC, or your laptop, or the device you happen to be using. You can think of the BIOS as the conductor. It’s the thing that starts everybody up. It gets the whole system running and makes sure that your operating system can then load and perform what it needs to do on its own. This is really just software that runs, and every machine has to have this BIOS software inside of it so that it knows what to do whenever you hit that power button.

This BIOS software that runs from your computer is something that loads every time from a read-only memory or some type of non-volatile memory inside of your computer. But there’s a lot of configuration settings that also have to be stored somewhere. And they are stored in a section of your computer called the CMOS.

This stands for complementary metal-oxide semiconductor. It’s a type of memory, and, although your computer may not necessarily be using this exact type of memory to store this information, we do generally still call it the CMOS. It’s just something that we use as a term these days, regardless of where this data happens to be stored.

This is usually a section of memory that is backed up with a battery. It’s storing your configuration information, and we have to make sure that, because this is volatile memory, that we’re always providing a little bit of power to this particular piece of memory. This is storing all the BIOS configuration of your computer. So information about the hard drive configuration, any floppy drive configuration, any optical media, how your keyboard happens to be set up, there are a lot of different options inside of your BIOS configuration, and those configuration settings are stored in the CMOS.

The configuration of the BIOS is not very large. Your CMOS is usually a storage area of about 128 to 512 bytes of information. So 512 characters, effectively, of space. So that’s not very large. Sometimes this is built into a section of the motherboard as a separate piece of memory. These days we’re finding that this BIOS configuration that we used to call the CMOS information is now simply being stored as part of the Southbridge.

If you look somewhere on your motherboard, you’ll probably find the battery that’s being used to power up your CMOS information. Make sure that it’s always there and available for you. If that battery ever goes bad, you’ll start getting messages when you start up your computer that tells you that the configuration settings are incomplete, or the configuration settings are missing. And every time you start your computer, you have to confirm the configuration before you can then continue on and boot up your system.

Sometimes, you can remove this battery, and it will wipe clean the configuration of your CMOS. These configuration settings might have passwords inside of them, so some people can find, by removing that battery, they can clear out any of the BIOS configurations that may have been set for password protecting your computer.

When you start up your computer, you will see a screen that tells you to press a certain key to start the set up process. That’s referring to configuring the BIOS settings and being able to store that information in CMOS. And usually, it’s a key like the delete key or the F2 key. You have to look at the boot up process and see if you can catch whatever it’s trying to tell you about going into the configuration mode.

If you’d like to try this yourself without damaging or changing any of your computer configurations, you can load up something like Microsoft Virtual PC. When it starts up, it gives you an option to go into a BIOS setting. If you have VM player, which is an absolutely free virtual machine that you can load up, you can load that, and it also has a BIOS configuration.

There’s another popular virtual machine called Virtual Box. You’ll find that at Unfortunately, virtual box does not have a BIOS configuration. So if you’re using Virtual Box, you’re trying to find that BIOS set up– it’s not in there. You’ll need to load the Microsoft, or need to load the VM player to be able to look into and simulate the process of using that BIOS setup.

You might also want to check, when you start up your computer, to see if there’s another key that might launch a diagnostics. This is a diagnostics that’s built into the BIOS. And when this is available , you can test all of your hardware without ever starting an operating system. Not all BIOS configurations have this available, but the ones that do, as you can see, can show you a really nice graphical display, go through a number of different tests, and allow you to easily access some diagnostics right there in the BIOS.

I’ve just started up this VMware virtual machine. I’ve given it a special set of settings in this virtual machine that sets a counter from five minutes, when it brings up this first screen, so that I could stop here and give you feel for what this looks like. So this looks like any other computer that you would be using, all the information that goes on the screen.

What you’re looking for is information that’s right here at the top, you can see the Phoenix BIOS that’s running 4.0, release 6.0. It gives you information about what you happen to be running. It has a memory check that’s taking place at your power-on self test that occurs. Here’s the information you’re looking for at the bottom. Hit F2 to enter setup. So that’s the special key we’re looking for that would allow us to start the BIOS configuration on this computer. And if I go to this screen and hit F2, you’ll see the BIOS screen pop up. And now I can perform whatever functions I need to change the configuration of the BIOS on this computer.

Before you make any changes to your BIOS configuration, make sure you have some documentation that shows what it was originally. Maybe make some notes on a sheet of paper. If you have a mobile device that can take pictures, take a picture of the screen. That way, if you need to put things back the way they were, you know exactly what the original settings were.

You don’t want to make any changes to your BIOS configuration unless you’re absolutely sure what those changes mean. There are a lot of different settings for timings and memory inside the BIOS, and some of those could have an adverse affect on the operating system itself. And did I mention you’ll want a back up?

If you make any changes in there, you may have to spend a lot of time with the BIOS trying to figure out what it was that caused this particular problem. If you’ve got a picture you can reference, it’s very easy, now, to go to that back up and put things exactly the way they were. Configuring your BIOS is a relatively simple process, and if you’ve followed these particular guidelines, you’re going to have no problems working with your computer systems BIOS.