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Stages of Information System development,[object Object],1) Requirement analysis : study the existing system & determine the requirements of User preparation of system study report.,[object Object],2) Systems Design (Logical Design) : Conceptualization of the new system based on system study report prepared in step 1. It deals with algorithm, database design , specification of interfaces between all programs to make a system, hardware, Operating system, file system & programming languages..,[object Object],3) Development of prototype : With a concept, design a model,[object Object],4) System Design (Physical Design) : Partitioning of the system in to programs, preparing a detail algorithm to the problem confronted with a detail database design, interfaces used, OS, H/w, S/w, file system and languages.,[object Object],5) Preparation of test data – About each individual stages & programs as well as system linking testing.,[object Object]

Approaches to algoithms,[object Object],Hardware - single / Multiple user environment.,[object Object],Data storage & retrieval – Magnetic tape, Hard disk, CD, DVD,[object Object],Input devices – Punched card reader, keyboard, digitizer, Mouse, Mike, Scanners.,[object Object],Output devices – Printers (laser, dot matrix, Ink jet), monitor.,[object Object],Operating system – default to the user environment (DOS, Windows, Unix, Xenix),[object Object],Language – Basic, Fortran, C, C++, DHTML, ASP. Net, etc. ,[object Object],Productivity tool – Program generators and application generator tools.,[object Object],Data Management - Conventional File system (Sequential) and Database Management System, RDBMS. ,[object Object],hbs.ac.in,[object Object]

Development of System Software,[object Object],S/w Development Trend,[object Object],Scheduled Operation,[object Object],Single Transaction Process,[object Object],Batch Sequential process,[object Object],On-demand operation,[object Object],Batch Indexed Sequential process,[object Object],Batch Random process,[object Object],Interactive,[object Object],Non-interactive,[object Object],Slow Response,[object Object],Fast Response,[object Object],Response in 24 hours,[object Object],Data read & updated interactively,[object Object],Data read & not updated interactively,[object Object],Response as soon as possible,[object Object],hbs.ac.in,[object Object]

Expert systems (ES) ,[object Object],It is a computer programs which make recommendations and draw conclusions from rules of thumb / heuristics and from the relationships derived out of human behaviour.,[object Object],It aids the manager in the process of decision-making by suggesting alternatives solutions in all desciplines.,[object Object],It provides expert advice by “domain specific knowledge”.,[object Object],Processing information requires knowledge , comprising judgement, experience, and reasoning of top management.,[object Object],A right decision can be made at the time – only when right information is available to the right man, in the right form, at the right time.,[object Object],The decision maker analyze, evaluate and reason with this knowledge along assistantship of specialized knowledge in an appropriate way.,[object Object],An effective decision has two components, Timeliness and Correctness i.e., quality and consistency in DM. ,[object Object],hbs.ac.in,[object Object]

Expert systems (ES) Outcomes,[object Object],Major activities like expansion, investment planning, raising fresh capital on a venture, make or buy analysis and dividend decisions by considering current economic conditions.,[object Object],Other decision like setting up or shutting down of a production unit/ line against the alternative of purchasing the item. ,[object Object],ES will give you an estimation of various costs involved and its association with each alternatives.,[object Object],It also draws control, design, monitor, predict and train middle level management for performance enhancer.,[object Object],Establishing control systems, budgeting, cash flow analysis, framing customer credit policies, forecasting income, expenses growth rates, accounts payable & receivable.,[object Object],Diagnosis, interpretation & monitoring of all the activities at the lower levels and application is virtually endless.,[object Object],hbs.ac.in,[object Object]

Expert systems Applications,[object Object],Establishing sales quotas.,[object Object],Conducting trainee orientation.,[object Object],Recommending acquisition strategies.,[object Object],General project proposals.,[object Object],Job shop scheduling.,[object Object],Facilities maintenance.,[object Object],Selection of forecasting models,[object Object],Determining credit limits, and,[object Object],Selecting transport routes.,[object Object],hbs.ac.in,[object Object]

Basis of Data Communication (DC),[object Object], By data communication we mean the transportation of information from one point to another through a communication media. ,[object Object], It facilities efficient use of large computers, improves the day-to-day monitoring of projects and provides a variety of services like e-mail, credit card checking, etc are valued added services. ,[object Object], The main components of DC are data source (originator), data sink (receiver), and communication media (telephone wire, co-axial cable, microwave, fibre-optic, satellite circuit).,[object Object],hbs.ac.in,[object Object]

Types of Data Communication (DC),[object Object],Electronic signals actually represents reality viz., pressure, temperature, stress that can be represented in equivalent electronic signals.,[object Object],Analog and Digital are the two types of e-signal.,[object Object],Analog signals are continuous in nature in a sinusoidal form, there is no break anywhere. E.g. speech in a microphone.,[object Object],Digital signals are discrete in nature i.e., present TRUE or not present FALSE. Computers uses only digital signals for data communication.,[object Object],MOdulator-DEModulator (MODEM) is a device that converts Analog to Digital and vice versa.,[object Object],hbs.ac.in,[object Object]

Types of Transmission ,[object Object],Transmission of data in either digital / analog form since signals may originate from several independent sources e.g. computers, FAX, Video conference, etc. (Baud, Bit, Byte, Nibble) ,[object Object],Analog transmission is similar like transmission through telephone network, they travel a longer distance and has noise interferences (electrical parlance) in it, that can damage the content & integrity of data at large.,[object Object],Digital transmission is less error prone, high quality, digital fidelity, and can’t travel long distance hence converted to electrical analog signal before transmission. They are not simply amplified, they are absorbed & regenerated at regular intervals, thus noise are eliminated.,[object Object],hbs.ac.in,[object Object]

Mode of Data Transmission ,[object Object],Serial mode – a stream of data bit by bit over the communication line. Initially a sender transmits the first bit, after some time (machine cycle) the second bit is transmitted and so on. The receiver receives the data exactly in the same format sequence bit by bit. The objective is to transmit data from one point to another along a single line or channel. The channel has an ability to carry a signal at a time (LSB, MSB). Receiver consequently has an ability to recognize the serial stream of bits as character.,[object Object],There are two techniques for recognizing and separating characters from the serial bit stream. They are synchronous and asynchronous transmission.,[object Object],During transmission if any error occurred, that particular bit is only lost and it operates on cost effective hardware. Transmission of 8-bit ASCII data requires 8 cycles of operation.,[object Object],Serial data transmission is done in three ways, viz. synchronous, asynchronous and Iso-syndronous.,[object Object],hbs.ac.in,[object Object]

Mode of Data Transmission ,[object Object],Parallel mode – Here all the bits of information are transmitted in a single cycle. ,[object Object],i) During transmission if any error occurred, whole set of data is lost and it operates on costly hardware. E.g. 8-bit ASCII code, all the 8 bits are transmitted over the communication media in a single cycle (i.e.,) eight-fold increase in the transmission speed. ,[object Object],ii) Limitations are the sender and receiver have to agree on the exchange of one or more characters using appropriate protocol (communication control methodology) – defines the content and the sequence of exchange of units of information (bits, bytes, or groups of bytes called PACKETS) b/w any two systems.,[object Object],iii) At high speeds of transfer using parallel transmission, protocols will be in the form of hardware signal exchanges (complex and expensive). Always used b/w subsystems of a computer system.,[object Object],iv) They are confined to shorter distance transmission (few feet).,[object Object],hbs.ac.in,[object Object]

Serial Mode of Data Transmission ,[object Object],Asynchronous Transmission – It is most commonly used transmission mode, where each character data to be transmitted is preceded by a start bit and terminated by one or two stop bits. It is also called as START/STOP transmission with indefinite time lag for the next character.,[object Object],i) The start signal tells the receiver where the new character starts and the function of stop bit is to tell the receiver that the character has ended, so that the next start bit will be perceived as the start of a new character. The receiver can know the end of the character by counting the number of bits. e.g person keying from a keyboard and getting the response from monitor.,[object Object],ii) Always , the two devices (terminal & computer), have to agree upon the number of bits in a character and the bit time. ,[object Object],iii) The speed ranges from 1200 bits per second to 9600 bits per second and applied b/w different devices of varying speed, e.g a Computer terminal with a dot matrix printer .,[object Object],iv) It is relatively simple to implement but its results are inefficient since it lack full utilization of channel capacity.,[object Object],hbs.ac.in,[object Object]

Serial Mode of Data Transmission ,[object Object],b) Synchronous Transmission – It is used to achieve high speed of data-transmission, where sender transmit a block of characters together in one single transmission. The transmission b/w them is achieved by transmission of a pre-determined group of bits known as synchronous bits.,[object Object],These synchronous bits inform the receiver that the data is following and he can determine the time frame b/w each of the bits. The receiver start receiving the bits and starts interpreting them bit by bit of 8 bits, into character from as per ASCII code and transmits to the computer.,[object Object],There are at least three SYN characters, followed by number of data characters and then finally the checksum character. ,[object Object],This type of transmission are done b/w device of same speed of operation. E.g. mother board RAM with cache memory.,[object Object],Discuss the difference b/w SYN and ASYN mode.,[object Object],hbs.ac.in,[object Object]

Serial Mode of Data Transmission ,[object Object], c) ISO-Synchronous Transmission – It is a technique which makes use of both synchronous and asynchronous data transmission modes. ,[object Object],i) Here each character starts with a start-bit and ends with a stop-bit. In addition, the time interval b/w transmission of two characters will be integer multiple of the length of the time required to transmit one character. (definite time lag).,[object Object],ii) A circuit is a path for transmission of electrical signals b/w two or more points. The termschannel, line, circuit, link or a path are synonymously used.,[object Object], iii) There are three types of transmission, viz. Simplex, half-duplex and full-duplex.,[object Object],Source,[object Object],Source,[object Object],Sink,[object Object],Sink,[object Object],Source,[object Object],Sink,[object Object],hbs.ac.in,[object Object]

Data Communication Software,[object Object],They are written in Assembly level language (hexadecimal or octal) and burnt into the microprocessor’s memory (ROM, EPROM). ,[object Object],Main functions of these software were : ,[object Object],a) Transmission initiation and termination,[object Object], b) Establishment of logical connections over physical line ,[object Object], c) Message assembly and deassembly,[object Object], d) data transmission and receipt,[object Object], e) code conversion,[object Object], f) error detection,[object Object], g) control character recognition.,[object Object], h) data editing,[object Object],i) data delivery,[object Object], j) data output,[object Object], k) transmission monitoring and maintenance,[object Object], l) Schedule and monitor all resources (H/w, S/W, data, etc).,[object Object],hbs.ac.in,[object Object]

Data Communication Protocols,[object Object], Primary Functions are,[object Object], a) At the lowest level, h/w protocols, like ASYN transmission protocol that operate b/w two synchronized devices.,[object Object], b) To make sure that the bits are securely transmitted through the channel or line, we need a link protocol b/w two computers. ,[object Object],Other functions are ,[object Object],1) Ensuring that the data to be transmitted is split into data blocks with beginning and ending markers, called FRAMING and transmission block is called FRAME,[object Object], 2) Achieving data transparency by allowing a link to treat a bit pattern, including normally restricted control characters.,[object Object], 3) Controlling the flow of data across the link at a faster rate and ensure overflow, underflow, ensuring buffering capacity used-up that leads to loss of data.,[object Object], 4) Controlling errors by detection using some redundancy check,[object Object], 5) BISYNC (Binary Synchrounousprocools) and HLDC (high level data link control protocol , TCP/IP),[object Object],hbs.ac.in,[object Object]

Seven layers of Open System International (OSI) Model,[object Object], Each of these layers performs certain specific functions,[object Object],1) Physical layer - It is the lower layer that support wide variety of physical media for interconnection by using suitable control procedures.,[object Object], 2) Data link layer – It provides methods for error-free transmission over the physical layer and above s.no.1.,[object Object], 3) Network layer – It performs the delivery of data through certain protocols such as routing and provides a communication path b/w two end-points.,[object Object], 4) Transport layer – It forms the uppermost layer of data transport service. It isolates high level entities from any concern of transport of data from one system to another & make transparent n/w to the users.,[object Object], 5) Session layer – It performs the job of the controller and synchronizes the dialogue session between the systems.,[object Object], 6) Presentation layer – It provides a general service not unique to a specific application (AL) & concerns with representation and manipulation of data.,[object Object], 7) Application Layer – It makes use of the service provided by the lower layers by providing interface to the user processes.,[object Object],hbs.ac.in,[object Object]

Data Transmission Error and Recovery,[object Object],Data while transmitted, may suffer some damage due to noise or distortion due to external disturbances or transmission medium itself.,[object Object],Please note 0 & 1 is send and received as 1 and 0, the given bit is either 0% error or 100% and nothing in between. Bit Error Rate (BRR) of the channel decides about the characters send per second is counted, where both serial and parallel mode (Block Error Rates) of transmission are tested.,[object Object],Since the channels are error prone, recovery mechanisms are a must. Even a single bit is lost, the whole character consisting of weight bits is lost. Protocol (set of rules governing info. flow in a communication system) decides who can talk and when, start-stop protocol helps in restricting loss to a character.,[object Object],Protocol has main purposes : ,[object Object],To ensure that the information is transmitted when and only when the communication channel is free and the appropriate terminal devices are read to receive ,[object Object],To prevent corruption or loss of information during transmission.,[object Object], The receiving terminal can then send a character to indicate wither that the block was error free or that an error occurred and a retransmission is required with an ACK signal and NAK signal.,[object Object],hbs.ac.in,[object Object]

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