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Northern India Engineering College, Shastri Park, New Delhi
Department of Information Technology
Notes for Second Term Exam
Fundamentals of Computing
Course Facilitator:
(Code ETCS – 111)
Dr Shafiq ul Abidin, HoD – IT
What is OS?
An operating system (OS) is a collection of software that manages computer hardware
resources and provides common services for computer programs
...
Application programs usually require an operating system to function
...
Real-time operating systems often use specialized scheduling
algorithms so that they can achieve a deterministic nature of behavior
...
They have an event-driven or time-sharing design and often aspects of both
...
Multi-user
A multi-user operating system allows multiple users to access a computer system at the
same time
...
Single-user operating systems have only one user but may allow multiple programs to
run at the same time
...
single-tasking
A multi-tasking operating system allows more than one program to be running at the
same time, from the point of view of human time scales
...
Multi-tasking can be of two types: pre-emptive and cooperative
...
Unix-like operating systems such as Solaris
and Linux support pre-emptive multitasking, as does AmigaOS
...
16-bit versions of Microsoft Windows used cooperative multitasking
...
Mac OS prior to OS X used to support cooperative multitasking
...
The development of networked computers that
could be linked and communicate with each other gave rise to distributed computing
...
When computers
in a group work in cooperation, they make a distributed system
...
They are designed to operate on small machines like PDAs with less autonomy
...
They are very compact and
extremely efficient by design
...
Windows 2000
Windows 2000 (W2K) is a est commercial version of Microsoft's evolving Windows
operating system
...
0, Microsoft emphasizes that
Windows 2000 is evolutionary and "Built on NT Technology
...
The Windows 2000 product line consists of four products:
Windows 2000 Professional, aimed at individuals and businesses of all sizes
...
It is the most economical choice
...
It can function as a
Web server and/or a workgroup (or branch office) server
...
NT 4
...
Windows 2000 Advanced Server, aimed at being a network operating system server
and/or an application server, including those involving large databases
...
NT 4
...
Windows 2000 Datacenter Server, designed for large data warehouses, online
transaction processing (OLTP), econometric analysis, and other applications requiring
high-speed computation and large databases
...
Windows 2000 is reported to be more stable (less apt to crash) than Windows 98/NT
systems
...
Windows 2000 and Windows NT
Windows NT 4
...
The two operating systems were released several
years apart: Windows NT 4
...
Owing in part to the
significant amount of time that passed between the releases of the two operating
systems, Windows 2000 has several features that Windows NT 4
...
Windows Administrative Tools
Task Scheduler
The Task Scheduler enables you to automatically perform routine tasks on a chosen
computer
...
Configure and administer Component Object Model (COM)
components
...
Event Viewer
Event Viewer
...
Print Management
Print Management
...
Local Security
Windows Firewall with Advanced Security
...
System Configuration
System Configuration
...
Windows Utilities
Paint
WordPad
Calculator
Calculator picks up a bunch of new functionality, including this handy mortgage calculator
...
Windows Calendar
Windows DVD Maker
Windows Media Player
Windows Fax and Scan
Microsoft Safety Scanner
Help protect your PC and remove malicious software (including Blaster, Sasser, and
Mydoom)
...
Skype for Windows
Keep in touch with the people you care about most
...
Windows 7 USB DVD Download Tool
Allows you to install a downloaded copy of Windows 7 onto your computer directly from
the USB flash drive or DVD
...
Windows System Registry
The Windows Registry is a hierarchical database that stores configuration settings and
options on Microsoft Windows operating systems
...
Overview of Linux OS
The Birth of Linux
On August 25, 1991, a Finn computer science student named Linus Torvalds made the
following announcement to the Usenet group comp
...
minux:
What is Linux?
Linux is, in simplest terms, an operating system
...
The operating system (OS) relays instructions from an
application to, for instance, the computer's processor
...
Explained in these terms, Linux is very similar to other operating systems, such as
Windows and OS X
...
The Linux operating
system represented a $25 billion ecosystem in 2008
...
As an open operating system, Linux is developed collaboratively, meaning no one
company is solely responsible for its development or ongoing support
...
This spreading of development burden amongst individuals
and companies has resulted in a large and efficient ecosystem and unheralded software
innovation
...
In the past two years alone, over 3,200 developers from 200 companies have
contributed to the kernel--which is just one small piece of a Linux distribution
...
Where is Linux?
One of the most noted properties of Linux is where it can be used
...
Other operating systems, such as Symbian, are found on small devices
such as phones and PDAs, while mainframes and supercomputers found in major
academic and corporate labs use specialized operating systems such as AS/400 and
the Cray OS
...
Linux is already successful on many different kinds of devices, but there are also many
technological areas where Linux is moving towards, even as desktop and server
development continues to grow faster than any other operating system today
...
Kernel - Core component of Operating System, interacts directly with hardware,
provides low level services to upper layer components
...
Takes
commands from user and executes kernel's functions
...
Components of Linux System
Linux Operating System has primarily three components
Kernel - Kernel is the core part of Linux
...
It is consists of various modules and it interacts directly with the
underlying hardware
...
System Library - System libraries are special functions or programs using which
application programs or system utilities accesses Kernel's features
...
System Utility - System Utility programs are responsible to do specialized, individual
level tasks
...
The Linux file structure branches into several directories beginning
with a root ( / ) directory
...
bin – It holds the essential command and binaries files needed to run the system in
single user mode
...
usr – contains user applications and supporting files
...
When a file is created then
it is automatically given read and write permission for the owner
...
Owner
Group
Others
Permissions is granted by using a set of octal number program
...
Command for File Permission
Change Mode Command is used to change the permission
...
chmod 766 filename
This command sets r/w/x permissions for owner and r/w permissions for group and
others
...
The name RPM variously refers to the
...
RPM was
intended primarily for Linux distributions; the file format is the baseline package format
of the Linux Standard Base
...
Deb Packages
Debian packages are standard Unix/Linux archieves that include two tar archives
optionally compressed with gzip (zlib), Bzip2, lzma, or xz (lzma2): one archive holds the
control information and another contains the program data
...
Computer Network
A network consists of two or more computers that are linked in order to share resources
(such as printers and CDs), exchange files, or allow
electronic communications
...
A computer network or data network is a telecommunications network that allows
computers to exchange data
...
The connections
(network links) between nodes are established using either cable media or wireless
media
...
Network devices that originate, route and terminate the data are called network
nodes
...
Two devices are said to be networked when a device is able to
exchange information with another device
...
Computer networks differ in the physical
media used to transmit their signals, the communications protocols to organize network
traffic, the network's size, topology and organizational intent
...
Some of the common ones include;
1
...
Quite often, a networked office building, home or
school contains a single LAN although it is normal to come across a building that
contains a few small LANs
...
Such computer networks are usually owned by one organisation
...
Wide Area Network WAN – As the name suggests, a WAN spans over a large physical
distance
...
The internet is a very good example of a WAN
...
In IP networking, both the LAN and WAN addresses are
maintained by the router
...
3
...
Quite often, such computer
networks are owned and operated by single entities such as government bodies or large
corporations
...
In the full mesh topology, each workstation is connected directly to each of the
others
...
The tree network topology uses two or more star networks connected together
...
Thus, a tree
network is a bus network of star networks
...
In many instances, the logical topology is the same as the physical topology
...
For example, some networks are physically laid out in a
star configuration, but they operate logically as bus or ring networks
...
Linear Bus
Star
Tree (Expanded Star)
Considerations When Choosing a Topology
Linear Bus
A linear bus topology consists of a main run of cable with a terminator at each end (See
fig
...
All nodes (file server, workstations, and peripherals) are connected to the linear
cable
...
Requires less cable length than a star topology
...
Terminators are required at both ends of the backbone cable
...
Not meant to be used as a stand-alone solution in a large building
...
2)
...
The hub, switch, or concentrator manages and controls all
functions of the network
...
This configuration is
common with twisted pair cable; however, it can also be used with coaxial cable or fiber
optic cable
...
Star topology
Advantages of a Star Topology
Easy to install and wire
...
Easy to detect faults and to remove parts
...
If the hub, switch, or concentrator fails, nodes attached are disabled
...
Tree or Expanded Star
A tree topology combines characteristics of linear bus and star topologies
...
3)
...
Fig Tree topology
Advantages of a Tree Topology
Point-to-point wiring for individual segments
...
Disadvantages of a Tree Topology
Overall length of each segment is limited by the type of cabling used
...
More difficult to configure and wire than other topologies
...
A linear bus network may be the least expensive way to install a network; you do not
have to purchase concentrators
...
The linear bus network uses shorter lengths of cable
...
With a star topology, expanding a network is easily done by adding another
concentrator
...
The most common cable in schools is unshielded twisted pair, which is most often
used with star topologies
...
In order for two computers to talk to each other, they must be speaking the
same language
...
The OSI (Open Systems Interconnection) Reference
Model defines seven layers of networking protocols
...
Communicating
systems use well-defined formats for exchanging messages
...
HTTP- HyperText Transfer Protocol - An Internet-based protocol for sending and
receiving webpages
...
For example, when
you enter
a URL in your browser, this actually sends an HTTP command to the Web
server directing it to fetch and transmit the requested Web page
...
HTTPS allows secure ecommerce transactions, such as online banking
...
A user can tell if they are connected to a secure website if the website URL begins
with https:// instead of http://
...
As the name suggests, FTP is used to transfer files
between computers on a network
...
Keep in mind, however, that many FTP sites are heavily used and require several
attempts before connecting
...
SMTP stands for Simple Mail Transfer Protocol
...
Most email software is designed
to use SMTP for communication purposes when sending email, and It only works for
outgoing messages
...
There
are two other protocols - POP3 and IMAP - that are used for retrieving and storing email
...
For example, your Internet server provider may provide you with a PPP
connection so that the provider's server can respond to your requests, pass them on to the
Internet, and forward your requested Internet responses back to you
...
It is sometimes considered a member of the TCP/IP suite of protocols
...
Essentially, it packages your computer's TCP/IP packets and forwards
them to the server where they can actually be put on the Internet
...
Most e-mail applications (sometimes called an e-mail client) use the POP
protocol, although some can use the newer IMAP (Internet Message Access Protocol)
...
The first, called POP2, became a standard in the mid-80's
and requires SMTP to send messages
...
TCP (Transmission Control Protocol) is a set of rules (protocol) used along with the
Internet Protocol (IP) to send data in the form of message units between computers over
the Internet
...
IP Internet Protocol (IP) is the method or protocol by which data is sent from one
computer to another on the Internet
...
Network Transmission Media
Transmission media is a pathway that carries the information from sender to receiver
...
Data is transmitted normally
through electrical or electromagnetic signals
...
An electromagnetic signal is series of
electromagnetic energy pulses at various frequencies
...
Transmission media is also called Communication channel
...
1
...
Wireless or Unguided Media or Unbound Transmission Media
Wired or Guided Media or Bound Transmission Media: Bound transmission media
are the cables that are tangible or have physical existence and are limited by the
physical geography
...
Each of them has its own characteristics like
transmission speed, effect of noise, physical appearance, cost etc
...
These
media are not bounded by physical geography
...
Nowadays wireless communication is becoming popular
...
This transmission
uses Microwave, Radio wave, Infra red are some of popular unbound transmission
media
...
Available in shielded and unshielded
versions
...
Atmosphere/Wireless
Uses Electromagnetic waves
...
Choose Media based on :
•
•
•
•
•
•
Wiring configurations
Distance and location limitations
Speed
Reliability
Security
Budget
Network Devices
Network devices /
hardware may also be known as network equipment, computer
networking devices
...
All these terms refer to devices facilitating the use of a computer network
...
There are number of network devices few of them are as follows:
Routers
A router is a network device that connects together two or more networks
...
The router will typically have the Internet cable plugged into it, as well as a cable, or
cables to computers on the LAN
...
(A wireless router is actually a router and wireless switch combined)
Routers work at the network layer (layer 3) of the Open Systems Interconnection (OSI)
reference model for networking to move packets between networks using their logical
addresses (which, in the case of TCP/IP, are the IP addresses of destination hosts on
the network)
...
A router is a network device that connects together two or more networks
...
The router will typically have the Internet cable plugged into it, as well as a cable, or
cables to
HUB
Networks using a Star topology require a central point for the devices to connect
...
The basic form of concentrator is the hub
...
Most common hubs interconnect
Category 3 or 5 twisted-pair cable with RJ-45 ends, although Coax BNC and Fiber Optic
BNC hubs also exist
...
Hubs offer an inexpensive option for transporting data between devices,
but hubs don't offer any form of intelligence
...
An active hub strengthens and regenerates the incoming signals before sending the
data on to its destination
...
Switches
Switches are a special type of hub that offers an additional layer of intelligence to basic,
physical-layer repeater hubs
...
This information allows switches to repeat incoming data frames only
to the computer or computers to which a frame is addressed
...
Switches operate at both the physical layer and the data link layer of the OSI Model
...
Whereas a router is usually used to link a LAN to a WAN (such as the Internet), a bridge
links independent parts of a LAN so that they act as a single LAN
...
They can also be used to divide large
networks into smaller segments
...
Bridges can also connect networks that run at different speeds, different topologies, or
different protocols
...
Bridges operate at both
the Physical Layer and the MAC sublayer of the Data Link layer
...
Network Interface Card (NIC)
Any computer that is to be connected to a network, needs to have a network interface
card(NIC)
...
The problem with using telephone lines is that they are designed to carry voices, which
are analogue signals
...
The solution was to use a special device to join the digital computer to the analogue telephone line
...