>> Hey everybody, welcome back to the course.
In the last video,
we talked about the foundational structure
of the hard disks or HDD,
the hard disk drive.
We also talked about what
SSD or solid-state drive stood for.
In this video, we're going to talk about bit,
byte, and nibble, along with some other topics as well.
Just the things you want to know between bit,
byte, and nibble if you're not familiar.
That is not a nibble, by the way, in the photo.
>> That's tribble.
>> But if you're familiar with Star Trek,
that's just a neat little photo to see.
Bit, basically, this is our foundational thing.
That's our binary digit, that zero, that one,
essentially that turning on or turning off,
for the electricity component of it.
We either have electricity on or electricity off.
Then we have our byte, which is eight bits,
and then also our nibble,
which is four bits, so half of a byte.
Keep those in mind for your actual examination
>> just in case you see anything about that.
>> The next thing we're going to talk about is
a BIOS parameter block or BPB.
Basically, this describes the physical layout
of the storage volumes.
You'll see it in things Windows-based.
You'll see it in things like FAT16, FAT32,
>> and then NTFS as well.
>> GUID or globally unique identifier.
Just know that this is 128 bits.
Basically, this is identifying information.
These can be generated,
and they're identifying some component of the system.
GPT or the GUID Partition Table.
Basically, this provides
a layout of the actual partition table.
You'll see this in HDD,
hard disk drive, or SSD or solid-state drives.
Then, just to mention, in here,
the header is a Logical Block Address 1.
Just keep that in mind for your examination as well.
UEFI or Unified Extensible Firmware Interface.
This is pretty much what we're seeing
nowadays as BIOSs are being phased out,
or if it's not already phased out.
Basically, this defines a software interface
between the actual operating system and the firmware.
That's always our graphic there.
Shows it's at an intermediary type of thing.
This also supports remote diagnostics as well.
Again, some features that BIOS doesn't have.
The UEFI boot process phases.
You'll just want to memorize these
>> for the actual examination itself.
>> We've got the security phase,
pre-EFI initialization, driver execution environment,
boot device selection, and run time.
We're going to talk about
>> each one of these a little bit.
>> Security phase or SEC handles
>> the platform restart events.
>> It also creates a temporary memory.
It serves as a root of trust as well,
which is pretty easy to remember
>> if you remember the component of security phase.
>> Then, of course, it passes off any
required hand-off information over to the PEI,
which is the next stage.
PEI or the pre-EFI initialization phase.
This one's going to initialize permanent memory,
and then also it's going to describe
>> that memory inside of HOBLs, or hand-off blocks.
>> It's going to describe the firmware
volume location as well.
Then, of course,
>> it passes it all along to the next level.
>> The DXE, or driver execution environment.
This one basically contains a DXE dispatcher
>> which discovers and executes the DXE drivers
>> and make sure they're executed in the correct order.
It also terminates at successful operating system boot.
Once everything comes up,
it's good to go.
Then, of course,
you know the drivers are going to
initialize a processor, the chipset,
>> and then alsothe platform components as well.
>> The boot device selection phase or BDS.
That's where we see the platform boot policy.
It also initializes consoles.
It's going to load the device drivers as well as
the boot selections and then also execute them.
Run time, so this enables the operating system
>> to read or write different environmental variables.
>> It also supports updates of firmware.
Then the main thing you want to remember
>> is that it clears UEFI from memory.
>> Just a quick post-assessment question here.
We talked about nibble earlier.
The question here, a nibble is six bits.
Is that true or false?
You're correct if you guessed false.
If you remember, a nibble is half of a byte,
so that's four bits.
A byte is eight bits.
A nibble is half of that.
It's going to be four bits.
In this video, we just talked about a bit,
byte and nibble, and talked about
how we can differentiate between those.
We also talked about
UEFI as well as the UEFI boot phases.
The next video, we're going to start jumping
into our actual file systems.
Before that, we'll actually jump
into our boot processes.
We'll talk about Windows,
Mac as well as Linux.
Now, we're not going to take
a deep dive into the boot process
because you don't need to know that
>> for the actual exam,
>> but I've listed out a few steps,
and we'll talk about that walk you through
>> how the boot process generally functions.