Transcript Software and Networking powerpoint - 2

Computer and
Information Science
Chapter 1.2
Computer Software and Networking
Agenda
Application Software
 Operating Systems

Software
Software is the programs and data that
a computer uses.
 Programs are lists of instructions for
the processor.
 Data can be any information that a
program needs: character data,
numerical data, image data, audio
data, and countless other types.

– Digitizing :The process of taking a visual image, or
audio recording and converting it to a binary form
for the computer.
Types of Programs
Imagine that you have just turned
on your computer and have not yet
started any application. Are any
programs running?
 Two types of software

– Application software
– System software/Operating systems
Why do we need an OS?

What are the goals of an Operating
System?
– The primary goal of an Operating System is
to make the computer system convenient to
use.
– The secondary goal is to make the computer
system efficient to use.
An Operating System
It underlies all other software.
 It acts as an interface between a user of a
computer and the computer hardware
 It manages and coordinates computer
system resources ( CPU, memory, file
system, I/O devices)
 It provides the user Interface that is:

– How can something as simple-minded as a processor and
memory present you with something as rich as the Mac or
Windows GUI?
Operating system services ...
Control
basic input
and output
Allocate
system
resources
Manage
storage
space
Operating Systems
Operating system services ...
Detect
equipment
failure
Maintain
security
System calls
• You ask MS Word to OPEN a document
– File menu/Open…
– WHAT WILL YOU SEE?
– What really just happened in the box?
WORD called on O.S. to present
you with that file list!
O.S. must look at:
1. Disk Directory (list of filenames)
2. File Allocation Table (FAT)…. (list
of file locations: starting
position/cluster number on the disk)
Multi-tasking

>1 program or person can share
computer resources.
– CPU is idle ~90% of time, waiting for user input !
– One program active; Others running in the
background

OS must protect each program’s memory area to ensure
that instructions and data don’t “leak” into an area
allocated to another program. If it fails, programs can
crash…more shortly!
Booting and BIOS


When a computer is started up, the
hardware will automatically load the
operating system and start it running. This
process is called booting.
BIOS is the boot program on a computer,
and controls the computer from the time
you start it up until the operating system
takes over. When you turn on a PC, the
BIOS first conducts a basic hardware
check, called a Power-On Self Test (POST),
to determine whether all of input/output
devices are present and working. Then it
loads the operating system into your
computer's RAM.
ROM (Read-only-Memory)
ROM refers to computer memory
chips containing permanent or
semi-permanent data. Unlike RAM,
ROM is non-volatile; even after you
turn off your computer, the
contents of ROM will remain .
 BIOS is stored in a ROM.

Various Operating Systems
Windows : Developed by Microsoft
XP, Vista, windows7
 Unix: Developed by AT&T for large
companies
 Linux: Open Source version of
Unix
 Mac OS: only for Mac hardware
e.g. Snow Leopard

Microcomputer Operating Systems
Why is it important for me to know which operating system
is on my computer?
UNIX
SunOS UNIX
UNIX features a command
line interface. Designed for
minicomputers but is now
also available for micros
and mainframes.
login: smith
Password:
Last login: Oct 15 17:42:09 from tserv1.edu
SunOS Release 4.1.1 #1: Wed Mar 20 11:24:14 AST 1991
You have mail.
%_
The UNIX prompt
IMPORTANT !
WHAT HAPPENS when you SHUT DOWN
improperly? Why should you care?
“Shutting down incorrectly is a little like
stopping your car by driving it into a wall.
It works, but it can cause some damage.”
Computer terms bingo
Follow the link
http://www.wcu.edu/ceap/Kirk/Merlot
_Resources/KnowYourComputerTe
rms.swf

Networks
Computer Network: series of
computers linked together to share
data, hardware, and software
 Local Area Network (LAN) : series
of computers networked together
over a relatively limited area

– campus
– building
Key Network Terms
Stand-alone computer — a computer not
connected to a network.
Workstation — name for a computer when it
is connected to a network.
Local resources — workstation’s typical
resources: hard drive, software, data, and
printer.
Network resources — additional resources
you have access to when connected to a
network: application software, storage
space for data files, and shared printers.
Network server — a computer connected
to the network that distributes
resources to network users.
Network printer — a shared printer that
provides output capabilities to all
network users.
Node — a device on a network, including
workstations, servers, and printers.
The login process ...
Identifies
you as a user on the
network
Logically connects a workstation to
network drives and other resources
Requires a user to enter a user ID
and password
User account — provides access to
network resources.
Network administrator or supervisor
— person responsible for setting
up user accounts and maintaining
the network.
What drives are available??
Mapping — assigning drive letters to
network server disk drives.
View a directory or access files
on network server drive F just as
you would drives A and C.
Network server drive F
Network
printer
Your workstation floppy drive A
Your workstation hard disk drive C
Using Programs on the Network
Step #1
Step #2
Step #3
Sharing a program — with proper licensing
many network users can access a program
at the same time and save...
Disk storage space
 Time and effort in updating
software
 Licensing costs

Using a Network Printer
Parallel port
Network printer
orkstation


The login process usually
assigns a network printer to
your workstation.
Output is redirected
(captured) from the parallel
port to the network printer.
Ceo.doc arrives first
Two documents are sent
to a network printer at
the same time . . .
Print Queue:
1. Ceo.Doc
2. Gnp.Doc
Gnp.doc arrives
before printer
completes Ceo.doc
Print queue — special holding area
on the network server where files are
stored until they are printed.
Network Hardware
Network interface card (NIC) —
small circuit board that plugs into
expansion slot.
– Key component for connecting your
computer to a local area network
– Sends data from a workstation over the
network
– Collects incoming data intended for your
workstation
Desktop network interface card (NIC)
Connecting Networks
Twisted pair cable (UTP) —
Similar to
telephone cable
 Has a plastic RJ45 connector on
either end

Other Network Connectors
Wireless networks use radio or
infrared signals to transmit data from
one network device to another.
The network interface card contains
the transmitting devices.
Wireless networks:



Provide mobility
Are used in environments where
wiring is hard to install
Can be good for temporary
installations
Software for Networks
A network requires some special
network software in addition to
much of the same application
software typical of standalone
computers.
Network license:
Permits specified number of people
to use software on a network
 Costs more than one single-user
license but less than individual
licenses for all network users
 Available for most software
packages by contacting the
publisher

E-mail
Electronic mail (e-mail) is
correspondence conducted
between users on a computer
network.
Store and forward
technology:
E-mail
messages are stored on a
server
When you read your mail, the
server forwards it to your
workstation
1. E-mail addressed to you
is sent to the mail server
Mail server
2. Mail stays on the
mail server until you
log on to your mail
client.
3. Server forwards your mail
to your workstation when
you’re ready to read it.
Your workstation
VOIP
VoIP allows you to make telephone
calls using the Internet.
 Voice communication among the
computers, free of charge
 Calls to phone numbers for a fee

Streaming Media

Streaming media technology enables
you to include audio, video and other
multimedia files into your web site.
Downloading vs Streaming


Downloading :The user
downloads the file from the web
server to her local hard disk, and
then plays back the content using
a player.
Streaming: The media Server
sends data over the network only
at the speed that is necessary for
the client to render it properly
and allows live content delivery.
More Internet Applications


FTP is a standard network
protocol used to exchange and
manipulate files over
the Internet.
Instant Messaging, originally a
real-time communication via the
Internet using typed text and
now includes voice and video