Hardware/Hardware Exercise Inside the Computer (35 minutes)

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2 Δεκ 2013 (πριν από 3 χρόνια και 11 μήνες)

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Hardware/Hardware Exercise


Inside the Computer (35 minutes)



Caution: When working with the internal components of a system, it is

important to discharge any static electricity before handling components.

Failure to do so can result in damaging co
mponents.



Caution: Do not use magnetic equipment, particularly screwdrivers, around

systems. Doing so can result in damage to magnetically stored data, namely

on hard disks.



Components



Keyboard/Mouse/Monitor


The mouse and keyboard are responsible

for
providing user input to the system and the monitor is responsible for
displaying data output from the system.



Removable Storage Devices


Devices that allow users to upload and
store information from a system. These include:


Floppy disks


CD/DVD devi
ces


Flash memory




Sound card
-



-

responsible for converting digtal signals to analog output and for

converting analog input to digital.


Has input/output connections for microphones and speakers.


Contain onboard memory and a DSP (Digital Si
gnal Processor), a
microprocessor that handles some computation on the card,
rather than the processor.



Graphics card


responsible for converting image data from the system into a
format that can be displayed by a monitor.


The graphics card is typically

required to do this around 60 times
per second, making the computation far too intense for the cpu
and system to handle alone.


A graphics card contains a processor and RAM. The processor,
called a GPU (Graphics Processing Unit) is specifically designed
f
or geometric computation.


The onboard ram gives the graphics card a place to store data and
completed images. The ram is located on
-
board to reduce the
amount of delay and usage of main memory.


Data for each pixel including location and color must be
stored,
with over a million pixels required for the average frame while
generating 60 frames per second, the graphics card is responsible
for some of the most intense computation in a system.


Newer graphics cards typically must be connected directly to the

power supply due to the power requirements.




NIC (Network Interface Card)


May be an ethernet card or, for example, a modem.


Used to transmit data to other computers in a variety of activities,
for example, accessing the internet, using instant messenger
programs, downloading files, and connecting remotely to other
computers.


Data is transmitted from the system through a network in packet
form and can be seen through applications such as ethereal.



Memory
-

RAM (Random Access Memory)


memory sticks comes in

a variety of sizes, most commonly
in sizes ranging for 128MB to 1GB or more.


The operating system is loaded from the hard disk and stored
in memory while in use.


Applications are loaded into RAM for execution.


When power to the memory is lost, the conte
nts of the
memory is also lost. This is why data is magnetically
written to hard drives for long term storage.


As an operating system works it goes through a series of
context switches, giving control to various applications for
very short periods of time
, so that they may execute, access
RAM, and other devices. When an application requires
more RAM than is currently free in the system, the
operating system must swap least used portions of memory
out to the hard disk, freeing portions of RAM for the
appli
cation's use.




CPU(Central Processing Unit)


responsible for the core computation
within a system. The CPU is responsible for the decision making
processes and handles virtually all aspects of operation.


executes low level machine language instruction
s


the processor performs 3 basic functions:


1) mathematical computation through add, subtract,


multiply, and divide instructions.


2) data location management through move instruction


3) jump instructions that allow it to move to different


locations and continue executing instructions.



Hard Disk


Hard disks use magnetic storage to provide a way to permanently
store data.


Local Data that must be “remembered” when a system is powered
off must be written to the hard drive, otherwise i
t will be lost
when the system is rebooted.


A hard drive is composed of several aluminum disk
-
like platters
that rotate at high speeds.



A read/write head is an armature that moves over the surface of
the disk and is capable of reading or writing data at t
hat location.

The read/write head does not touch the disk, if this occurs the
resulting “head crash” will result in damaged disk sectors and
can frequently result in loss of the entire drive.


Standard Hard Disks rotate at 7200rpm, a hard disk that operat
es
through a SATA (Serial
-
ATA) interface can reach speeds of
10,000rpm and high end servers with a SCSI interface freqently
operate hard disks that rotate at 15,000rpm.


The rotational speed of the hard drive determines how quickly a
location on the disk ca
n be rotated under the read/write head
and, therefore, is a major factor in determining how quickly data
can be accessed.


Important performance factors for hard drives are:


data rate


the rate at which data can be read or written.


seek time


the time be
tween a CPU's request for data
and the actual time when the first byte is delivered. It is
heavily influenced by a number of factors including the
speed with which the disk rotates under the head.



Motherboard


The motherboard is the main circuit board.

All
components are connected through the motherboard.





CPU Socket


The CPU is mounted to the motherboard through this


interface. Motherboards support different sockets, the



socket
refers to the number of pins on the chips.




On
-
board battery


used to maintain BIOS information even when the




computer is powered off.





PCI (Peripheral Component Interconnect) Ports


* The PCI bus allows components to
be connected to the


system bus, allowing them to communicate with the


processor.


* The most recent PCI standards allow for 64
-
bit transfers at


speeds 113MHz, or 1 Gbps.


* Can be used to connect various c
ards to the system. For
example network cards, sound cards, usb cards, and some
graphics cards.





AGP (Accelerated Graphics Port)


* The demands of graphics cards increased to a point
where high end cards could no longer be supported on

the PCI bus.


* The AGP port provides a high bandwidth dedicated line
to the cpu built specifically for graphics cards.





Chipset


connects the processor to the rest of the system. Composed of


the North Bridge and South Bridge.



Nor
th Bridge


responsible for connecting the processor to the


front side bus, which includes the connection to memory, PCI,



and AGP.



South Bridge


slower than the North Bridge. Data is


transmitted through th
e north bridge first, then goes to the south


bridge. It is used to access devices such as IDE and SATA


hard disks as well as USB devices.




Power supply


can be easily found due to the power cord and fan.


responsible for converting Alternating Curren
t to Direct Current.


A variety of cables can be found leaving the power supply. Each
of the cables provides power for various devices from hard
disks, CD/DVD drives, and graphics cards to various other
devices that maybe attached.


As devices are added to

the system, it may be necessary to
upgrade to a larger power supply in order to support the added
energy use.


If the power supply fails the system will not operate. There are
obvious indicators when a power supply fails, including the
failure of the syst
em to attempt booting and the loss of power
indicator lights on the motherboard.



Operating Systems Installation/Material




Begin Ubuntu installation (4 minutes)



History


Early computers did not have operating systems. Instead, they required a
human o
perator to manually enter input for a single process.


The first operating systems did not surface until the 1960s.


Since then, operating systems have developed from the simplest of
command line interfaces to advanced Graphical User Interfaces(GUIs)
des
igned to provide user
-
friendly environments.



Common Operating Systems:


Microsoft Windows


approximately 90% of users run Windows.


Linux


there are several different flavors of linux, each with their own
advantages. Ubuntu Linux has grown in popular
ity due to its focus on a
user
-
friendly interface. Other popular variants include RedHat Fedora,
Gentoo, Mandrake, and Debian, among others.


Mac OS


Developed by Apple for their Mac computers.


UNIX


developed by Bell Labs, frequently used on servers.
Linux is a
variant of UNIX.


Palm OS


deisgned for Palm's PDAs. Operating Systems aren't only
designed for standard computers; most cell phones, handheld organizers,
and equipment requiring a high degree of user interaction have their own
operating system
s.




What is an Operating System?


a program designed to load, monitor, and restrict the execution of other
programs/processes.


Responsible for Managing Applications and Hardware resources.


Provides an Interface to System Hardware




Application and Hard
ware Resource Management


manages the system's software and hardware resources.


Allows multiple applications and processes to run, seemingly,
simultaeneously by periodically giving small time slices to each
process. During the time period the process can e
xecute code,
perform memory accesses, send data to the disks, and handle
other operations.


Responsible for sharing the CPU, memory, I/O bandwidth, and
storage among all competing process.


Without an operating system requiring processes to play fairly,
th
ere would be no restriction on the resource use of applications
and a single process could easily starve others of needed
resources.



Interface to System Hardware


provides an interface to the system hardware, allowing application
programs to easily interf
ace with hardware, without knowing all of its
details.


-

Operating systems provide an Application Program Interface (API)


to developers.


-

An API provides the ability for software developed on one system to
run properly on another system r
egardless of differences in memory,
storage, and hardware.



Initial Ubuntu Installation Should be Complete


Reboot and begin installation of





Multiple Operating Systems (20 minutes)




There are several methods that allow users to access multiple ope
rating


systems.


Multiple hard drives

-

This method is very simple from software installation standpoint, but
more time consuming from a hardware aspect.


-

The hard disk is responsible for maintaing the copy of your operating


system that is load
ed into main memory when you boot up a computer.


-

Simply installing different operating systems on different hard drives


and physically changing the devices will allow you to boot the


different operating systems.


-

This technique is most
effective when you already have very
important data on a hard disk that is too large or difficult to back up and
restore, but still need to use the system, either with a different operating
system or for potentially dangerous work that might damage the dat
a.



Dual Boot

-

This method is both hardware and software driven.

-

Involves partitioning your hard drive.

-

Instead of physically replacing hard drives, we can take a hard disk and,
essentially, have the system treat it as two seperate disks.

-

In order

to do this you must start operating system installation from
scratch, losing any data already present on the disk.

-

During the setup process for the operating system, prior to the actual
installation, you will notice that you are given the option to par
tition the
hard disk. During this stage, simply create two partitions to split the
drive in two.

-

The partitioner requires you to select a partition size and will create the


partition.

-

One partition can hold your copy of windows, the other can h
old a


version of linux (or other combinations of operating systems).

-

It is generally a good idea to install Windows first and Linux second,
since Windows will wipe out the master boot record and recovering it
can be difficult.

-

Once both operating

systems are installed, you will notice that when
you attempt to boot your system, before it begins to load an operating
system it takes you to a boot menu that will ask which operating system
you would like to load.



Virtual Machines (demo)

-

This is a
heavily software driven method of running multiple operating
systems that allows uses to run multiple operating systems
simulataenously on a system.


The virtual machines emulate the host system and provide the appearance,
to users, of having complete con
trol over the hardware, when in reality it
may be shared among many virtual machines and the host operating
system.


Each virtual machine may run different operating systems, each with a
wide variety of their own applications.


The Virtual Machine Monitor or

Hypervisor is responsible for the
interfacing between the operating system and hardware.


They provide an excellent environment for executing untested code and
for the hosting of services vulnerable to attack. If a number of services
are hosted on a bas
e system, for example web servers, database servers,
user accounts, etc, and a single attack through one service takes out the
entire system, all of the other services are taken out with it. If virtual
machines are used to host each service independently,

then an attack on
any service can only take out the virtual machine running that service,
leaving the others unaffected. (demo
-
fork bomb on a base system and on
a VM?)







Closing Information:


Hardware/Operating System Interaction
-

Bootup


When a sys
tem is powered on, instructions in ROM(read
-
only
-
memory)
are executed, making certain that the hardware is functioning properly.


Disk drives are then powered on and the bootstrap program is located and
executed.


The bootstrap program is responsible for l
oading the operating system into
memory and setting up the data structures used by the operating system.


The operating system then assumes control and begins execution.