BIOS and UEFI - CompTIA A+ 220-901 - 1.1

when you first start up your computer before it loads an operating system or does anything relating to Windows or Linux or Mac OS it first runs some software called the basic input/output system this is the starting point for everything else that runs on your computer even if there were no storage devices in your computer and no operating systems at all you would still be able to run the basic input/output system you may hear this referred to as the firmware or the system bios or the rom bios there's ROM or flash memory all of these are similar names we use to describe this basic input/output system the first thing that the BIOS does is initialize your system it makes sure that you have all of the hardware components needed to continue with loading an operating system so it checks to see if you have a CPU installed and if that CPU is performing properly it checks the memory and make sure that you have memory installed onto your motherboard and does a basic check of the hardware we call this basic check a power-on self-test or a post and if any of these very quick Hardware checks fail for any reason it'll pop up a message on the screen telling you that there's a problem with your CPU or with your memory and then prompts you for correcting that particular issue after it finishes the power-on self-test it then goes to your storage devices and looks for a bootloader that it can then use to handoff to the operating system and your computer can continue to load your operating system normally that BIOS software has to live somewhere on your motherboard and if you've got your motherboard documentation it probably has a block diagram of the motherboard and it will show you where the BIOS chip happens to be you may want to open up your system and see if you can identify where the BIOS is that's what I did with my motherboard this is one that I have in my studio you can see there are some PCI Express slots on here you've got a battery that's used we'll talk more about the battery in a moment some other chipsets and then there's a very small chip right here on the right side right here in the middle and if we zoom up on that you can see the words BIOS are written right on the chip I couldn't even find it I needed to go to my motherboard to show me exactly where this was and if you look close enough you'll be able to find that chip somewhere on your piece of hardware whenever you start up your computer there are going to be one of two different kinds of BIOS that may run one is the legacy BIOS and there's also a newer type of BIOS called the UEFI BIOS the legacy BIOS has been around for a very long time for over 25 years if you've worked with computers at all during that time you're probably accustomed to seeing this very familiar BIOS screen it's all text and you can see that you can configure different settings inside of the hardware from this front end it's a piece of technology that allows operating systems in some cases to talk directly to hardware although these days the operating systems tend to use device drivers that then communicate with the hardware but very early on in computing we were able to talk directly to Hardware through this BIOS there's usually a limited amount of hardware these legacy BIOS systems will understand this legacy BIOS doesn't know that a network card is connected to your system you can't browse the internet or download files because there's no way to do it inside of this legacy BIOS the modern kind of BIOS that we find on all of our new systems these days is the UEFI BIOS or the UEFI BIOS this stands for the unified extensible firmware interface and it's based on a standard from Intel called the extensible firmware interface manufacturers will take this standard and they'll create a basic input/output system front-end specific to their hardware and what they're doing is following this standard that is used across all different manufacturer systems this is effectively replacing that legacy BIOS you'll no longer see the legacy BIOS being used and we'll use the UEFI BIOS for all of our modern systems when you're using a modern UEFI BIOS you now have a number of new capabilities one of its bigger advantages is booting from larger and larger storage systems we have very large hard drives and very large storage systems these days and having a BIOS that can support these very large gooood partition table or GPT disks is very important the iOS can also support the legacy fat formats it can support booting from removable media and these are capabilities we simply didn't have with a legacy BIOS the UEFI BIOS also provides a pre boot environment this is something that we can use when troubleshooting the computer before the operating system has even loaded if we're having problems with the operating system we can use this pre boot environment to be able to go to a command line to transfer files on to a storage device to even bring up a browser and browse the Internet be able to communicate over the network the UEFI BIOS front-end usually has some remote Diagnostics as well so someone can start up their UEFI BIOS and you can connect to it remotely to see what's going on inside of that computer without any additional software or operating system when you're making all of these configuration changes inside of your BIOS there needs to be a place to store all of these configuration settings we've traditionally done this by storing it in non-volatile BIOS memory this takes all of your settings that you've been working on and keeps them inside of your computer we used to save this to a type of memory called the complementary metal-oxide-semiconductor or the CMOS well very often still refer to it as CMOS memory even when it isn't these days we're using flash memory to store this information and not the older CMOS one of the disadvantages of CMOS is that you had to have some type of power source to always keep your configuration settings active inside of that memory if you lost the power it would lose all of the settings that's why these days we tend to use flash memory to store this information it doesn't need a constant power source it's much more flexible and reliable when it comes to storing our BIOS configurations if you're working with an older motherboard you'll probably see a battery like this somewhere on the motherboard and it's being used to provide that constant power to maintain your BIOS settings if you unplug your computer and you move it to another location and plug it in again it will still retain your BIOS configurations because this battery was there even on newer motherboards you may still see a battery somewhere it's used these days to maintain the date and time so that you don't have to constantly reset that every time you turn on your computer it this battery goes bad and it's being used to maintain the bio settings and what you'll find is that you'll get a message every time it boots up it says all of your bio settings are now removed you have to now go back into the BIOS make sure all the configuration settings are correct so that you can then start your computer and you'll have to do that every time you power up your computer on older systems you used to be able to reset everything in the BIOS then by simply removing the battery if you wanted to reset your BIOS after making an incorrect configuration or you want to remove some of the passwords that were stored inside the BIOS that was a very easy way to reset everything back to factory defaults you

Channel: Professor Messer

Views: 1,036,760

Keywords: a+, 220-901, certification, comptia, free, james messer, professor messer, bios, uefi, computer

Id: SlzwMKcCoMI

Length: 7min 29sec (449 seconds)

Published: Sun Nov 29 2015