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Friday, August 16, 2013

PPT On Process Description and Control


Process Description and Control Presentation Transcript:
1.Process Description and Control

2.Requirements of an Operating System
Interleave the execution of multiple processes to maximize processor utilization while providing reasonable response time
Allocate resources to processes
Support inter process communication and user creation of processes

Computer platform consists of a collection of hardware resources
Computer applications are developed to perform some task
Inefficient for applications to be written directly for a given hardware platform
Operating system provides a convenient to use, feature rich, secure, and consistent interface for applications to use
OS provides a uniform, abstract representation of resources that can be requested and accessed by application

4.Manage Execution of Applications
Resources made available to multiple applications
Processor is switched among multiple application
The processor and I/O devices can be used efficiently

A program in execution
An instance of a program running on a computer
The entity that can be assigned to and executed on a processor
A unit of activity characterized by the execution of a sequence of instructions, a current state, and an associated set of system instructions

6.Process Elements
Program counter
Memory pointers
Context data
I/O status information
Accounting information

7.Process Control Block
Contains the process elements
Created and manage by the operating system
Allows support for multiple processes

8.Process Control Block

9.Trace of Process
Sequence of instruction that execute for a process
Dispatcher switches the processor from one process to another

10.Example Execution

11.Two-State Process Model
Process may be in one of two states

12.Not-Running Process in a Queue

ready to execute
waiting for I/O
Dispatcher cannot just select the process that has been in the queue the longest because it may be blocked

14.A Five-State Model

15.Suspended Processes is faster than I/O so all processes could be waiting for I/O
Swap these processes to disk to free up more memory
Blocked state becomes suspend state when swapped to disk
Two new states
Ready Suspend

PPT On Process


Process Presentation Transcript:
1.Introduction to Process

2.Outline Process Concept
Process Scheduling
Operations on Processes
Cooperating Processes
Inter process Communication

3.Process Concept
An operating system executes a variety of programs
batch systems - jobs
time-shared systems - user programs or tasks
job and program used interchangeably
Process - a program in execution
process execution proceeds in a sequential fashion
A process contains
program counter, stack and data section

4.Process Control Block
Contains information associated with each process
Process State - e.g. new, ready, running etc.
Program Counter - address of next instruction to be executed
CPU registers - general purpose registers, stack pointer etc.
CPU scheduling information - process priority, pointer
Memory Management information - base/limit information
Accounting information - time limits, process number
I/O Status information - list of I/O devices allocated

5.Process Scheduling Queues
Job Queue - set of all processes in the system
Ready Queue - set of all processes residing in main memory, ready and waiting to execute.
Device Queues - set of processes waiting for an I/O device.
Process migration between the various queues.
Queue Structures - typically linked list, circular list etc.

Long-term scheduler (or job scheduler) -
selects which processes should be brought into the ready queue.
invoked very infrequently (seconds, minutes); may be slow.
controls the degree of multiprogramming
Short term scheduler (or CPU scheduler) -
selects which process should execute next and allocates CPU.
invoked very frequently (milliseconds) - must be very fast
Medium Term Scheduler
swaps out process temporarily
balances load for better throughput

7.Process Profiles
I/O bound process -
spends more time in I/O,  short CPU bursts, CPU underutilized.
CPU bound process -
spends more time doing computations; few very long CPU bursts, I/O underutilized.
The right job mix:
Long term scheduler - admits jobs to keep load balanced between I/O and CPU bound processes

8.Context Switch
Task that switches CPU from one process to another process
the CPU must save the PCB state of the old process and load the saved PCB state of the new process.
Context-switch time is overhead;
system does no useful work while switching
can become a bottleneck
Time for context switch is dependent on hardware support ( 1- 1000 microseconds).

9.Process Creation
Resource sharing
Parent and children share all resources.
Children share subset of parent’s resources - prevents many processes from overloading the system.
Parent and children share no resources.
Parent and child execute concurrently.
Parent waits until child has terminated.
Address Space
Child process is duplicate of parent process.
Child process has a program loaded into it.

10.Process Termination
Process executes last statement and asks the operating system to delete it (exit).
Output data from child to parent (via wait).
Process’ resources are deallocated by operating system.
Parent may terminate execution of child processes.
Child has exceeded allocated resources.
Task assigned to child is no longer required.
Parent is exiting
OS does not allow child to continue if parent terminates
Cascading termination

Resource Sharing
Utilization of MP Architectures

12.Kernel Threads
Supported by the Kernel
Windows XP/2000
Tru64 UNIX
Mac OS X
Mach, OS/2

13.Multithreading Models

14.Many user-level threads mapped to single kernel thread
Solaris Green Threads
GNU Portable Threads

Each user-level thread maps to kernel thread
Windows NT/XP/2000
Solaris 9 and later

PPT On Operating System Overview


Operating System Overview Presentation Transcript: 
1.Operating System Overview - 2

2.Operating System
A program that controls the execution of application programs
An interface between applications and hardware

Makes the computer more convenient to use
Allows computer system resources to be used in an efficient manner
Ability to evolve
Permit effective development, testing, and introduction of new system functions without interfering with service

4.Layers of Computer System

Portion of operating system that is in main memory
Contains most frequently used functions
Also called the nucleus

6.Evolution of an Operating System
Hardware upgrades plus new types of hardware
New services

7.Evolution of Operating Systems
Serial Processing
No operating system
Machines run from a console with display lights, toggle switches, input device, and printer
Schedule time
Setup included loading the compiler, source program, saving compiled program, and loading and linking

8.Simple Batch Systems
Software that controls the sequence of events
Batch jobs together
Program branches back to monitor when finished

9.Special type of programming language
Provides instruction to the monitor
What compiler to use
What data to use

10.Hardware Features
Memory protection
Do not allow the memory area containing the monitor to be altered
Prevents a job from monopolizing the system

11.Privileged instructions
Certain machine level instructions can only be executed by the monitor
Early computer models did not have this capability

12.Memory Protection
User program executes in user mode
Certain instructions may not be executed
Monitor executes in system mode
Kernel mode
Privileged instructions are executed
Protected areas of memory may be accessed

Processor must wait for I/O instruction to complete before preceding

When one job needs to wait for I/O, the processor can switch to the other job

15.Time Sharing
Using multiprogramming to handle multiple interactive jobs
Processor’s time is shared among multiple users
Multiple users simultaneously access the system through terminals 

PPT On Transaction Processing System


Transaction Processing System Presentation Transcript: 
1.Transaction Processing and Management Reporting System

2.MIS Framework

3.Transaction Processing System
A transaction is any event that takes place either within the business organization or between that organization and the external environment.
This information is not directly involved in the decision-making process but is needed by management.
It must be compiled and classified, perhaps calculations must be made, and finally it must be summarized in a form in which it will be maximally useful to management.
A transaction is an elementary activity conducted during business operations.
Such regular transactions include regular ordering of raw materials, customer billing and bank deposits etc.

4.A transaction is any event that takes place either within the business organization or between that organization and the external environment.
This information is not directly involved in the decision-making process but is needed by management.
It must be compiled and classified, perhaps calculations must be made, and finally it must be summarized in a form in which it will be maximally useful to management.
A transaction is an elementary activity conducted during business operations.
Such regular transactions include regular ordering of raw materials, customer billing and bank deposits etc.

5.The Management Reporting system is a set of reports that provide the information necessary to make business decisions
The Management Reports inform you about the sales and margin, about merchandising issues, about inventory, and about deals.
Management reporting systems provide routine, detailed, and voluminous information reports specific to each manager’s areas of responsibility
 Generally, such reports focus on past and present activities, rather than projecting future performance

6.Decision Support Systems
Decision Support Systems (DSS) are a specific class of computerized information system that supports business and organizational decision-making activities.
A properly designed DSS is an interactive software-based system intended to help decision makers compile useful information from
raw data
personal knowledge
business models to identify and solve problems and make decisions.
A knowledge-based system (KBS) is a system that uses artificial intelligence techniques in problem-solving processes to support human decision-making, learning, and action.

7.Office Information System
An  automated  office  information  system  (OIS)  attempts  to  perform  the  functions  of the  ordinary office  by  means of a  computer system. 
Automation  in  the  office particularly aids  the office  worker in  document  preparation,  information management  and decision  making.

8.Transaction Processing Functions
Process of keeping full, accurate, up-to-date business records
Proper bookkeeping can help businesses effectively manage cash flow, with knowledge of profits and losses, and develop plans for the future based on financial trends
With no exceptions, every monetary amount that is paid or received must be recorded.
Production of documents such as pay checks, invoices, periodic statements and payment reminders
Necessary for the effective operation of the company
9.Control reporting
Control report are produced as the by product of transaction processing operation
Serve operation control purposes
Normally used to check the accuracy of cash flow
Example: payroll edit report
Error report is used to show invalid transactions that were incomplete and must be reprocessed
Exception report is used to flag the unusual transactions

10.Role of IT in Transaction Processing
Problems with manual systems
Error level
Temporary and permanent loss of data
Labor intensity
Poor level of services
Poor response 
MIS systems
Converting manual systems in automatic systems
Direct translation of manual systems  (direct coding)
Re_thought before converting  

11.Transaction Processing Cycle
Data entry
Transaction processing
File and database processing
Document and report generation
Inquiry processing

12.Data Entry
Collecting, recording, coding and editing transaction data
Source documents are batched and transferred to data entry specialists
After manual audit, data from acceptable source document are converted to machine readable form (key to tape/ key to disk systems)
SDA (source data automation)? capturing data in digital form
enables the computer system from one company to “talk” to the computer system of another company and digitally exchange data.
Because this digital exchange of data is facilitated using computers, most, if not all of the associated business processes can be automated so they occur with little or no manual data entry.
This enables companies to electronically exchange business documents like purchase orders and invoices.
Increase in productivity without increasing staff

13. Transaction Processing and File/ database Updating
Transaction processing is done after collection of data in two ways
Real time processing
In a real time processing, there is a continual input, process and output of data. Data has to be processed in a small stipulated time period (real time), otherwise it will create problems for the system. 
For example: assembly line robots and radar system.
Batch processing
In a batch processing group of transactions collected over a period of time is collected, entered, processed and then the batch results are produced.
Batch processing requires separate programs for input, process and output. It is an efficient way of processing high volume of data.
For example: Payroll system, Examination system and billing system.

14.Documents and Report Generation
Documents produced by TPS are called transaction documents
Information documents
Turn around doc
Action doc
Accounting statements
Control listing
Edit reports

15.Information documents
Verify, confirm or prove that transactions have occurred or were attempted
Sales receipt
Order confirmation
Customer invoices
Customer statements
Turn around doc
Contains perforated tear off portion that should be returned to the sender along with the customer payments
Usually read by magnetic/ optical scanners
Action documents
Initiate actions or transactions on part of recipients
Example: paycheck, purchase order

PPT On Switching And Networks


Switching And Networks Presentation Transcript: 
1.Switching & Networks

A switch network consists of a series of interlink nodes called switches.
These are hardware and software devices capable of creating connections between two or more devices link to the switch.

3.Taxonomy of switched networks
Circuit switching
 Packet switching
Packet switching
In packet-based networks,  the message gets broken into small data packets. 
Each packet may go a different route from the others.
Each packet is sent with a ‘header address’.  This tells it where its final destination is, so it knows  where to go. The header address also describes the sequence for reassembly at the destination computer so that the packets are put back into the correct order.
If a packet fails to arrive, the recipient computer sends a message back to the computer  which  originally sent the data, asking for the missing packet to be resent.

4.Circuit switching
Circuit switching creates a direct physical connection between two devices such as computer or phones.
Advantages of circuit switching
 Once the circuit is set up communication is passed and error free.
 It is highly reliable.
Disadvantages of circuit switching
Takes a relatively long time to set up the circuit
 During a crisis or disaster, the network may become unstable or unavailable.
 Inefficient – the equipment may be unused for a lot of the call, if no data is being sent,  the dedicated line still remains open

5.Circuit Switching Communication
 Circuit establishment
 Data transfer
 Circuit disconnect
Circuit  establishment
Before any signals can be transmitted and end to end circuit must be established.
Data  transfer
Information can know be transmitted that can be analog or digital.

6.Circuit  disconnect
After some period of data transfer the connection is terminated.
EXAMPLES: Public telephone network

7.Telecommunication components
A public telecommunication network consists of the
 Subscriber line

 The devices that attach to the network
 Most subscriber devices in public communication networks are telephones.
Subscriber line:
The link between subscriber and network are called subscriber line.
 The switching centers in the network
 A switching center that directly support subscriber is known as end office.
The branches between exchanges
Trunks carry multiple voice frequency circuit using FDM or TDM.

9.Communications Network
The end devices that wish to communicate maybe referred to as stations.
The switching devices, connected to each other in some topology by transmission links are the nodes.
Each station attaches to a node, and the collection of node is referred to as a communications network.

A station is a device that a user interacts with to access a network and it contains the software applications that allows someone to use the network.
It maybe a microcomputer, a workstation, a cell phone or a mainframe.

A node is a device that allows one or more station to access a physical network and is a point to transfer information through the network.

12.Switching Concepts
Digital switch
Most important in modern systems
Function is to provide transparent signal path between any pair of attached devices
Allows full duplex mode

The network-interface element represent the functions and hardware needed to connect digital devices, such as data processing devices and digital telephones, to the network.

14.Control Unit
The control unit has three general tasks
Establish connection on demand
Maintain the connection
Tear down the connection

Multistage switch-The solution to limitation of the crossbar switch is the multistage switch which combines crossbar switches in several(normally three)stages.
In a single crossbar switch, only one row and one column is active for any connection. So we need n*n cross points. If we can allow multiple paths inside the switch ,we can decrease the no of cross points.
 Each cross points in the middle stage can be accessed by multiple cross points in the first or third stage.
 The multistage switch has one drawback-blocking during periods of heavy traffic. The whole idea of multistage switching is to share the cross points in the middle stage crossbars.

PPT On Sequential Circuit And Tabulation Method


Sequential Circuit And Tabulation Method Presentation Transcript:
 1.Sequential Circuit & Tabulation Method

2.Sequential logic contains the logic gates whose output at any instant of time depends upon the present input and also the previous inputs.
Memory elements are required in sequential circuits.
 It consists of combinational circuits to which memory elements are connected to form a feedback path.

These are the devices capable of restoring binary information within them.
The binary info stored in memory elements at any given time defines the state of sequential circuit.
The sequential circuit receives binary information from external inputs. These inputs together with the present state of memory elements determine the binary value at output terminals.

4.There are too many types of sequential circuits. There classification depends and the timing of their signal.
Synchronous Sequential
Asynchronous sequential circuit is a system whose behavior can be defined from the knowledge of its signal and its discrete signal of its time.

5.Asynchronous Sequential:
The behavior of asynchronous depends upon the order in which its input signal change and can be effected at any instant of time.
An asynchronous sequential circuit may be regarded as a combinational circuit with feed back path.

Synchronization is achieved by timing device called master clock generator which generates a periodic train of clock pulses.

Synchronous sequential circuits that use clock pulses in the inputs of the memory elements are called clock sequential circuit. The memory elements used in clocked sequential circuits are called flip-flops.

These circuits are binary cells capable of storing 1 bit information. A flip-flop circuit has two outputs; one for normal value and one for complement value of the bits stored in it.
A flip-flop circuit can be constructed from two NAND gates or two NOR gates. Each circuit forms a basic flip-flop. The cross coupled connection from the output of one gate to the input of the other gate constitutes a feedback path for this reason the circuits are classified as asynchronous sequential circuits.

8.NAND implementation of Flip Flops

9.Tabulation Method
Also known as Quine McCluskey
It is functionally identical to K-map.
There are 4 steps of this method
Step 1:
Write all the given numbers in form of table

10.Step 2
Write their binary equivalent in next column and make groups according to the number of 1’s in the minterm and mark tick

11.Check the binary equivalents for 1 bit change . if a 1 bit change occurs then write the binary number with (-) in column of step 3.
One bit difference implies adjacent
Repeat until nothing left.

12.Again check the binary equivalent for 1 bit change including (-) and mark tick in front of the values whose 1 bit is changed only.
One bit difference implies adjacent.
These are the prime implicants.
Repeat until nothing left.
Then find the expression

13.For Finding Expression
First check for the unmarked number in Step 3 and write the expression of that unmarked value then write the expression of step 4.

PPT On Spectroscopy


Spectroscopy Presentation Transcript:

2.What is Spectroscopy?
Spectroscopy pertains to the dispersion of an object's light into its component colors (i.e. energies). By performing this dissection and analysis of an object's light, astronomers can infer the physical properties of that object (such as temperature, mass, luminosity and composition).

3.The Nature of Light

4.Notice that radio, TV, and microwave signals are all light waves, they simply lie at wavelengths (energies) that your eye doesn't respond to. On the other end of the scale, beware the high energy UV, x-ray, and gamma-ray photons! Each one carries a lot of energy compared to their visible- and radio-wave brethren. They're the reasons you should wear sunblock, for example.

5.General Types of Spectra
Typically one can observe two distinctive classes of spectra: continous and discrete. For a continuous spectrum, the light is composed of a wide, continuous range of colors (energies). With discrete spectra, one sees only bright or dark lines at very distinct and sharply-defined colors (energies). As we'll discover shortly, discrete spectra with bright lines are called emission spectra, those with dark lines are termed absorption spectra.

6.Continuous spectra arise from dense gases or solid objects which radiate their heat away through the production of light. Such objects emit light over a broad range of wavelengths, thus the apparent spectrum seems smooth and continuous. Stars emit light in a predominantly (but not completely!) continuous spectrum. Other examples of such objects are incandescent light bulbs, electric cooking stove burners, flames, cooling fire embers and... you. Yes, you, right this minute, are emitting a continuous spectrum -- but the light waves you're emitting are not visible -- they lie at infrared wavelengths (i.e. lower energies, and longer wavelengths than even red light). If you had infrared-sensitive eyes, you could see people by the continuous radiation they emit!

7.Discrete Spectra
   Discrete spectra are the observable result of the physics of atoms. There are two types of discrete spectra, emission (bright line spectra) and absorption (dark line spectra). Let's try to understand where these two types of discrete spectra.

8.Emission Line Spectra
In the diagram below, a hydrogen atom drops from the 2nd energy level to the 1st, giving off a wave of light with an energy equal to the difference of energy between levels 2 and 1. This energy corresponds to a specific color, or wavelength of light -- and thus we see a bright line at that exact wavelength! emission spectrum is born, as shown below:

9.A hydrogen atom in the ground state is excited by a photon of exactly the `right' energy needed to send it to level 2, absorbing the photon in the process. This results in a dark absorption line.

Spectroscopy is the use of the absorption, emission, or scattering of electromagnetic radiation by matter to qualitatively or quantitatively study the matter or to study physical processes. The matter can be atoms, molecules, atomic or molecular ions, or solids. The interaction of radiation with matter can cause redirection of the radiation and/or transitions between the energy levels of the atoms or molecules.

11.The Light of Knowledge is an often used phrase, but it is particularly appropriate in reference to spectroscopy. Most of what we know about the structure of atoms and molecules comes from studying their interaction with light (electromagnetic radiation). Different regions of the electromagnetic spectrum provide different kinds of information as a result of such interactions. Realizing that light may be considered to have both wave-like and particle-like characteristics, it is useful to consider that a given frequency or wavelength of light is associated with a "light quanta" of energy we now call a photon. As noted in the following equations, frequency and energy change proportionally, but wavelength has an inverse relationship to these quantities.

12.Mass Spectrometry: Sample molecules are ionized by high energy electrons. The mass to charge ratio of these ions is measured very accurately by electrostatic acceleration and magnetic field perturbation, providing a precise molecular weight. Ion fragmentation patterns may be related to the structure of the molecular ion. •   Ultraviolet-Visible Spectroscopy: Absorption of this relatively high-energy light causes electronic excitation. The easily accessible part of this region (wavelengths of 200 to 800 nm) shows absorption only if conjugated pi-electron systems are present. •

13.Infrared Spectroscopy:
 Absorption of this lower energy radiation causes vibrational and rotational excitation of groups of atoms. within the molecule. Because of their characteristic absorptions identification of functional groups is easily accomplished. •
 Nuclear Magnetic Resonance Spectroscopy: Absorption in the low-energy radio-frequency part of the spectrum causes excitation of nuclear spin states. NMR spectrometers are tuned to certain nuclei (e.g. 1H, 13C, 19F & 31P). For a given type of nucleus, high-resolution spectroscopy distinguishes and counts atoms in different locations in the molecule. 
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