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System
System is an aggregate of two or more physical components and a set of disciplines or procedures by means of which they interact.
A set of elements or components that are formed and interact to accomplish goals or objective.
A subsystem is system component that is a system in its own right.
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Input
Productive resources that can be defined as natural resources.
Input can be inform of raw materials, labor, capital, information, data, or any other phenomenon that carries some form of content.
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Output
The result of the production process.
It is the goal that the system has as
its purpose for existing.
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Process/Transformation
Process is the method by which the goal of the system is achieved.
Steps or operations the system goes through to converts inputs into outputs.
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Feedback
Information returned to an instigator of change that reflects the result of that change, allowing the originator to correct for undesired results.
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System Boundary
A system boundary defines what is inside and what is outside of the system.
The boundary separate the system from its environment.
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Environment of System
The environment is everything outside of a system’s boundaries that is pertinent to the system.
It contains the sources of inputs into the system and the recipients of outputs from the system.
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Boundary and Environment
Customer
Receive Mail
Process Order
Computer
Order
Confirmation
Availability
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Boundary and Environment
System receives inputs from its environment.
System returns output to its environment.
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Connections in a System
The connection in a system transmit the flows of material and information that coordinate the system’s components.
Connections are essential to all systems.
Without connections, the system would be a set of independent components that ignore each other.
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Control Mechanisms
The control mechanisms in a system are the rules and logic that govern the individual subsystems and the interactions among them.
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Example
Supplier
Design ServiceDeliver SellProduce
Customer
OrderPreferences
Servicerequest
Parts
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Open System
Open system means they receive input from the environment and return output to the environment.
There is a flow of inputs and outputs across the system boundary.
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Closed System
There is no interaction with the environment within a closed system.
A closed system have sealed boundaries and neither receive inputs nor produce outputs
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Simple Systems
A simple system is one in which there are few elements or components and the relationship or interaction between elements is uncomplicated and straightforward.
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Complex System
A complex system is one in which there are many elements that are highly related and interconnected.
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Stable or Dynamic
Stable is one in which changes in the environment result in no change or little change in the system.
Dynamic system is one that undergoes rapid and constant change due to changes in its environment.
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Adaptive or Nonadaptive
An adaptive system is one that responds to a changing environment.
A nonadaptive system is one that does not change with a changing environment.
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Describing and Evaluating Systems
Cost of ownership The cost of implementing, operating,
and maintaining a system.Efficiency
The ratio between outputs and inputs for a particular task.
Delays Time lags between different things that
happen in a system.
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Describing and Evaluating Systems
Capacity The amount of work a system can do.
Reliability The extent to which a system can
dependably remain in service.Complexity
How complicated a system is, based on the number of differentiated components, the number of interacting components, and the nature of interactions between components.
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Describing and Evaluating Systems
Compatibility The extent to which the standards and
logic of one system is consistent with the standards and logic of another system.
Controllability The user’s ability to immediately
influence or change what a system does.
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Describing and Evaluating Systems
Adaptability The user’s ability to modify a system
over time as business conditions or other requirements change.
Likelihood of operator error the likelihood of mistaken or incorrect
action by people who operate equipment or system.
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Types of Tasks
Structured So well understood that is possible to
specify exactly how to perform the task.Semi-structured
less well understood; information requirements and procedures are generally known, but some aspects of the task still rely on the performer’s judgment.
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Types of Tasks
unstructured poorly understood; can not specify
information to be used, the method of using the information, nor the criteria for judging performance of the task; relies heavily on the performer’s judgment.
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Information System (IS)
An information system is combination of work practices, information, people, and information technologies organized to accomplish goals in an organization. An airline reservation system travel
agents use to book flights for their customers.
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Computer Based IS (CBIS)
CBIS is an information system that uses computer systems, devices, and technology.
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Computer Based IS (CBIS)
CBIS consists of: hardware software database telecommunication people procedures
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Computer Based IS (CBIS)
hardware keyboard scanner magnetic ink characters reader central processing unit memory storage printer monitor
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Computer Based IS (CBIS)
Software programs and instruction given to the
computer
Database organized collection of facts and
information
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Computer Based IS (CBIS)
Telecommunication link computer systems together into
effective networks.Local-area Network (LANs)Wide-area Network (WANs)
People people who enter, process, and use data
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Benefit of IS
Better serviceLess errorsHigher quality productsLess expensiveLess laborMore control over operations
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Modeling
Model is a copy of a physical structure or a concept that is designed to demonstrate certain characteristics of that physical structure or concept in accordance with the purposes of modeler.
Model is an abstraction or an approximation of reality.
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Types of Model
Narrative verbal and written descriptions of reality
Verbal designed to convert thoughts and
concepts into language, to establish relationship and restrictions of real-world systems, and then to organize them.
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Types of Model
Physical a tangible representation of reality. a model designed to resemble a
physical reality, though not to behave in an analogous manner.
Schematic graphical representation of reality
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Types of Model
Mathematical arithmetic representation of reality. a symbolic manipulative representation
of reality designed to describe relationships among certain factor of the reality that it is designed to represent.
uses numerical representation to describe the reality in question.
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Types of Model
Analog a model that behaves in some manner
similar to the reality that it is designed to represent.
These type of model are useful in investigating and understanding physical phenomena. They often produce large amount of information.
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Modeling Process
Gather information.
Based on this information, reach conclusions about the nature, characteristics, and behavior of the reality to be modeled.
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Modeling Process
Determine an appropriate form of model; what elements are important degree of detail required
Build the model
Compare the model with reality to determine the degree to which the model actually approximate the reality.
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Exercise
Using the modeling process outlined develop a model for some real-world phenomenon in which you are interested. Go through the process and document your choices of form, method, and so forth.
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Problem Solving
Process of using information, knowledge, and intuition to solve a problem that has been defined previously.
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Problem Solving Factors
ComplexityCompetitionSocial and political actionsTechnologyTime compressionDecision objectiveInternational aspects
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Characteristics of Data, Information, Knowledge
Distinguishing factorsTypes of dataAccuracy and precisionAge, timeliness, and time horizoncompleteness and level of
summarizationAccessibilitySourceValue and relevance
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Data, Information, Knowledge
Data data are facts, images, or sounds that
may or may not be to pertinent or useful for a particular task.
Information information is useful data whose form
and content are relevant and appropriate for a particular use.
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Data, Information, Knowledge
Knowledge knowledge is a combination of instincts,
ideas, rules, and procedures that guide actions and decisions.
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Relationship between Data, Information, Knowledge
Accumulateknowledge
Data
Format,Filter,
Summarize
Interpret,Decide,
ActResults
knowledge
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Type of Data
Formatted Data formatted data include numerical or
alphabetical items arranged in a prespecified format in which the meaning of each item is defined in advance.
Text text is a series of letters, numbers, and other
characters whose combined meaning does not depend on a prespecified format or definition of individual items.
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Type of Data
Images images are data in the form of pictures,
which may be graphs generated from formatted data, photographs, or hand-draw pictures.
Audio audio is data in form of sounds.
Video video data combine pictures and sounds
that are displayed over time to portray action.
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Accuracy and Precision
Accuracy accuracy is the degree to which the
data portray what is supposed to be portrayed.
Precision precision is the fineness of detail in the
portrayal
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Age, Timeliness, and Time Horizon
Age the age of data is the amount of time that
has passed since the data were produced.Timeliness
timeliness is the extent to which the age of the data is appropriate for the task and user.
Time horizon the time horizon of data is the interval of
time that data cover.
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Completeness and Level of Summarization
Completeness completeness is the extent to which the
available information seems adequate for the task.
Level of summarization Level of summarization is comparison
between the number of individual items upon which data are based and the number of items in the data presented.
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Accessibility, and Source
Accessibility accessibility is the extent to which the
user can obtain the information in time to use it effectively and in a format that makes it useful.
Source source of data is the person or
organization that produced the data.
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Value and Relevance
Relevance relevance is the extent to which data
can be converted into information that helps a person do a job or make decisions.
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What Is a Computer?
Computer is a system.The computer, also called a
processor, is an electronic device that can interpret and execute programmed commands for input, output, computation, and logic operations.
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Computer System Components
Input devicesOutput devicesCPU- Central Processing Unit
Arithmetic Logic Unit (ALU) Control unit Registers
Storage
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Computer System Components
CPU-the portion of the computer system that controls execution of program instructions and the processing of data items.
Elements of CPU Arithmetic Logic Unit (ALU) Control unit Registers
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Computer System Components
Storage-retention of programs or data on media such as: hard disks floppy disks compact disks tapes
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Types of Computers
Microcomputers personal computers workstations
Minicomputers Mainframe computersSupercomputers
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Types of Computers
Microcomputers PC-Personal Computer Laptop/ Notebook -a portable
microcomputer that weighs less than 12 pounds and can be fit into briefcase.
Palmtop- a pocket microcomputer that weighs less than 1 pounds and has limited function.
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Types of Computers
Minicomputers a computer that is smaller in capacity
and price than a mainframe but that delivers full-system capabilities.
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Types of Computers
Mainframe computers a large computer, so named because in
the past the main processing unit of this computer consisted of a series of circuit boards mounted within a frame structure.
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Types of Computers
Supercomputers the most expensive, largest computer;
can process over 1 billion instructions per second.
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Execution of an Instruction
Instruction Phase Fetch instruction Decode instruction
Execution Phase Execute the instruction Store result
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Primary Storage
Random access memory (RAM)Read only memory (ROM)Programmable ROM (PROM)Erasable PROM (EPROM)
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Data Manipulation
Representing and type of data bits and bytes standardized codes
ASCII-American Standard Coded for Information interchange
EBCDIC-Extended Binary Coded Decimal Interchange
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Storage Capacity
Storage capacity is measured in bytes A bit is a binary digit (0 or 1). Byte = 8 bit Word = 2 bytes = 16 bits Double word = 2 words = 4 bytes = 32
bits
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Boost speed
Miniaturization vacuum to transistors to integrated
circuit to microprocessorsReduce instruction set computing
(RISC)Parallel processingOptical processing
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Software
Software consists of computer programs that control the workings of the computer hardware, along with the program documentation used to explain the programs.
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Programs
Program Programs are set of instructions or
statements to the computer.Program documentation
Program documentation is the collection of narrative descriptions designed to assist in the program’s use, implementation, and operation.
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Program
Program code Program code is the set of instructions
that signal the CPU to perform circuit switching operations.
Programming Writing or coding instruction.
Programmer individual doing the writing or coding.
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Programming: a Translation Process
User
Idea of whatthe systemshould do
Writeprograms
Translate
Computer
Rules and limitation of programming language
Instructionthe computercan execute
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Types of Software
Application software tells the computer how to perform tasks
that structure or automate specific work practices.billing systemsinventory systems
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Types of Software
End-user software tells the computer how to perform tasks
that support general work practices such as writing memos and performing calculations.word processorsspreadsheet programsdatabase systems
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Types of Software
System development software helps analysts and programmers build
information system.compilersdatabase management systemCASE system (computer-aided software
engineering)
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Types of Software
System software controls or supports the operation of the
computer system so it can execute application software or end-user software.operating systemutility programs
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Testing Programs
Syntax errors incorrect use of the programming
language .Logical errors
bugs that cause a program to perform incorrect processing.
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Generation of programming languages
First Machine language
Second Assembly language
Third High-level language
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Generation of programming languages
Fourth Query and database languages
Fifth Object oriented language
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Operating System
Operating systems are complex programs that control the execution of other programs and use of computer system resources.
Operating system runs or control the computer hardware and acts as an interface with application programs.
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Operating Systems
Allocating resources and running jobs
Controlling jobs in progressControlling access to dataInterfacing with the user
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Criteria for Selecting Software
Fit to the business situationEase of useCompatibilityConversion requirementLong term direction
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Periodic signal
A signal is periodic if and only if
s(t + T) = s(t) for all values of t
T is the period of the signal.
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Analog signal
An analog signal is a continuously varying electromagnetic wave that may be propagated over a variety of media, depending on spectrum.
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Digital signal
A digital signal is a sequence of voltage pulses that may be transmitted over a wire medium.
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Characteristics of a periodic signalAmplitude
instantaneous value of a signal at any time.
Frequency the inverse of the period (1/T), or the
number of repetition of the period per second; it is expressed in cycles per second, or hertz (Hz).
Phase measure of the relative position in time
within a single period of a signal.
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Spectrum and bandwidth
Spectrum of a signal is the range of frequencies that it contains.
Bandwidth of a signal is the width of the spectrum in which most of the energy in the signal is contained.
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Transmission
Data transmission occurs between transmitter and receiver over some transmission medium.
Transmission media may be classified as guided or unguided.
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Guided media
With guided media, the wave are guided along a physical path; example of guided media are:
twisted paircoaxial cableoptical fiber
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Unguided media
Unguided media provide a means for transmitting electromagnetic waves but do not guide them; examples are propagation through:
airvacuumseawater
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Direct link
The term direct link is used to refer to the transmission path between two devices in which signals propagate directly from transmitter to receiver with no intermediate devices, other than amplifier or repeaters used to increase signal strength.
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Point-to-Point
A guided transmission medium is point-to-point if it provides a direct link between two devices and those are the only two devices sharing the medium.
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Point-to-Point
Transmitter/receiver Medium
Amplifieror repeater
Medium Transmitter/
receiver
0 ormore
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Multipoint
Transmitter/receiver
Medium Amplifieror repeater
Transmitter/receiver
Transmitter/receiver
Transmitter/receiver
Medium
0 or more
….
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Simplex transmission
In simplex transmission, signals are transmitted in only one direction; one station is transmitter and the other is receiver.
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Half-duplex transmission
In half-duplex transmission, both station may transmit, but only one at a time.
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Full-duplex transmission
In full-duplex transmission, both station may transmit simultaneously. In this case the medium is carrying signals in both direction.
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Telecommunication Devices
ModemsFax modemsSpecial purpose modemsMultiplexers
TDM FDM
Communication processors
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Telecommunication Carriers & Services
Common carriers AT&T MCI Sprint
Value added carriers Telnet SprintNet
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Switched Lines
Switched line is a standard telephone line that uses switching equipment to allow one transmission device to be connected to other transmission devices.
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Private Branch Exchange
PBX is a communications system that can manage both voice and data transfer within a building and to outside lines.
PBX can store callsPBX can transfer callsPBX can serve as a connection
between different office devices
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Wide Area Telecommunication Service
WATs is a billing method for heavy users of voice band media.
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Integrated Services Digital Network
ISDN is a technology that uses existing common carrier lines to simultaneously transmit voice, video, and image data in digital form.
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Communication Protocol
Open System Interconnection (OSI)Transmission Control
Protocol/Internet Protocol (TCP/IP)System Network Architecture (SNA)EthernetX.400X.500
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SOI
Physical layer transmits the data from one node to
another.Data link layer
format the data into a record called a frame and performs error detection.
Network layer causes the physical layer to transfer the
frames from node to node.
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OSI
Transport layer enable the user and host nodes to
communicate with each other.Session layer
initiate, maintains, and end each session.Presentation layer
formats the data so that it can be presented to the user or the host.
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OSI
Application layer controls user input from the terminal
and executes the user’s application program in the host computer.
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Data Transfer Modes
Packet switchingFrame relayVoice over frame relayAsynchronous transfer mode (ATM)
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Internet
The internet is the world’s largest computer network.
It is a collection of interconnected networks, all freely exchanging information.
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Internet Protocol
The set of conventions used to pass packets from one host to another is known as the internet protocol (IP)
TCP (transport control protocol is widely used.
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Ways to connect to internet
LANSLIP ( serial line internet protocol) or
PPP (point to point protocol)On-line service
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World Wide Web (www)
WWW is a collection of over 30,000 independently owned computer that together as one in an internet service.
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Web Browser
Web browser creates a unique, hypermedia based menu on your computer screen that provide a graphical interface to the the Web.
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Hypermedia
Connects the data on pages, allowing users to access topics in whatever order they wish.
Allows you to bring up pictures, graphs and other displays with sound and motion.
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Web Search Engine
Web search engines take the place of the card catalog.
They are software programs that allow you to search for information on the Web.
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Cryptography
Cryptography is the process of converting a message into a secret code and changing the encoded message back to regular text. (digital signature)
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Firewalls
The most popular method of preventing unauthorized access to corporate computer data to construct is known as a firewall.
Firewalls can be a set of filtering rules or specially configured hardware.
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Zone
edu = educational sitesmil = militarygov = governmentnet = networking organizationsnom = individualsorg = organizationcom = commercial
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Telnet and FTP
Logon to another computer and access its public files.
Copy a file from another computer to your computer.
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Phase Shift Keying (PSK)
To encode binary data by transition or shift from one phase to another.
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Bit Synchronization
Coordination of signal measurement timing is called bit synchronization.
There are two methods of bit synchronization: Asynchronous Synchronous
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Asynchronous Bit Synchronization
Massages begin with a start bit so that the receiving device can synchronize its internal clock with the timing of the massage.
Asynchronous transmissions are normally short, and the end of message is signaled by a stop bit.
Media is idle and the sender’s and receiver’s clocks are not synchronized when no data is being transmitted.
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Synchronous Bit Synchronization
Clocks of the sender and receiver are synchronized by one of the following methods: guaranteed state change separate clock signal oversampling
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Baseband & Broadband Transmissions
Baseband: these transmission use the entire media bandwidth for a single channel. Most LAN use baseband signaling.
Broadband: these transmission provide the ability to divide the entire media bandwidth into multiple channels.
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Selecting NIC
Type of network Token Ring, Ethernet, ATM,…etc
Type of media coaxial cable, STP, UTP, fiber,…etc
Type of bus ISA, EISA, VESA,…etc
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Bus Architectures
ISA (Industry Standard Architecture) 8 bit and 16 bit bus (10MHz)
PCI (Peripheral Computer Interconnect) 32 bit or 64 bit bus
EISA (Extended Industry Standard Architecture) 32 bit bus built on the ISA architecture (33
MHz)
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Bus Architectures
MCA (Micro Channel Architecture) 32 bit bus. MCA can work in 16 or 32 bit
mode. (66MHz)
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Estimating Memory Requirement
Minimum amount needed for Server operating system (16 MB) plus
Number of people who will be accessing the system at the same time plus
Average software requests per user.
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Hard Disk Capacity
Operating system files.Software files.Data and database files.User files.General public files.Utility files.Server management files.
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Fault Tolerance
Fault -tolerance options disk mirroring disk duplexing redundant array of inexpensive disks
(RAID)there are eight levels of RAID.
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Project
Set up a NIC in windows NT Server, once the NIC operating system are installed. Click Start button select Settings select Control Panel double click Network icon click Adapters tab click Add button
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Project
Notice the list of adapters that can be install
click Cancel click Cancel close the control Panel
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Windows NT networking Models
Workgroup model is a decentralized networking model. All account administration is local to
each machine. Each machine maintains its own
account database
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Windows NT networking Models
Client-server model is a centralized networking model. All administration is centralized at
server. Clients can log on to a server via the
server’s account database and access resources associated with that server.
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Windows NT networking Models
NT domain model Allows administrators to group users. All administration is centralized to an NT
Server that has been designated as he primary domain controller (PDC).
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Windows NT networking Models
In NT domain model the account database that resides on the PDC is called Security Account Manager (SAM)
SAM database is copied to server that has been designated as Backup Domain Controllers (BDC)
Each domain need al least one server
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Windows NT networking Models
PDC contains the master copy of SAM for the entire domain and is the only server that can make changes to the database.
If there is more than one server in a domain, selected servers can be designated to keep a backup copy of the SAM.
PDC’s SAM database is read-write.
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Windows NT networking Models
Domain models: single domain single master domain multiple master domain complete trust domain
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Windows NT networking Models
Criteria for choosing Domain models: # of accounts (windows NT can support
up to 40,000 account). The geographic scope of your domain. How users ant resources will be defined
within the domain.
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Domain Trust Relationship
In situation where there are two or more domains, users can access domains other than their own through trust relationships set up by the network administrator.
Each trust relationship has two parties: trusted domain
granted access to resources
trusting domaingranting the access
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Example
A n organization has a main office and ten branches, each with its own file server and domain. Main office domain needs access to all branches, which is granted. Main office is trusted domain, and branches are the trusting domains
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Trust Relationships
One-way trust the trust relationship is not reciprocated.
One domain is trusted party, and the other is trusting
Two-way trust the trust relationship is reciprocated.
Universal trust two-way trust are set up among more than
two domain.
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Single Domain
Consists of a single domain.Easy to manage.Centralized administration.Good for small networks.Slow when supporting large # of
accounts.
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Single Master Domain
Several domain are controlled by master domain.
All account are in the master domain.
Other domains containing only resources, such as servers.
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Single Master Domain
All resources are located at resource domains and can be available to all users.
Resources are decentralized.Administrators in the resource domain
have control over their resources. All user account are centralized in a
master domain.
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Multiple Master Domain
Consists of multiple single master domain connected through two-way trust relationships.
Administration can be centralized or decentralized.
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Multiple Master Domain
Number of trusts (n) can be determined as follow:
n=M(M-1)+(R+M)M=# of master or accounts domainsR=# of resource domains
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Complete Trust Domain
Accounts and resources are located in each domain.
Allows decentralized account management.
Each account can implement policies specific to their domain.
N(N-1)=n where N represents # of domain