Information System Analysis And Design (iSAAD) COSC 327 PDF

INFORMATION SYSTEM ANALYSIS AND DESIGN (iSAAD) COSC 327 DR. ABEL SAM B. CS DEPT. SYSTEM ANALYSIS AND DESIGN COSC 314 (3 CREDITS) * General systems concepts. General Introduction to systems Information system components. Types of information system. Systems development life cycle (SDL...

INFORMATION SYSTEM ANALYSIS AND DESIGN (iSAAD) COSC 327 DR. ABEL SAM B. CS DEPT. SYSTEM ANALYSIS AND DESIGN COSC 314 (3 CREDITS) * General systems concepts. General Introduction to systems Information system components. Types of information system. Systems development life cycle (SDLC): examples linear/waterfall, prototyping, spiral etc. Preliminary Investigation: feasibility activities. System analysis: determining requirements- facts finding techniques e.g interviews, questionnaire, observation etc. Analyzing requirements- structured analysis. DFD, process description tools e. g decision tables/tree, structured/tight English etc. Introduction to object-oriented system analysis: Overview of object modeling, UML. System Design: general guidelines, output design e.g printed reports, screen output, tapes etc. Input design e.g data entry screen design, help screen design. Real life case studies to provide experience in applying the principles and techniques presented. Prerequisite: COSC 202,INSY 241. Essentials of System Analysis and Design 5th ed. – J. Valacich, et. Al.,(Pearson, 2012) General Introduction to systems Introduction to System Analysis and Design Systems are created to solve problems. One can think of the systems approach as an organized way of dealing with a problem. In this dynamic world, The subject System Analysis and Design, mainly deals with the software development activities Defining A System A collection of components that work together to realize some objective forms a system. Basically there are three major components in every system, namely input, processing and output General System Interconnection and Objectivity We are also bound by many national systems such as political system, economic system, educational system and so forth. The objective of the system demand that some output is produced as a result of processing the suitable inputs. Definition of System There are many common types of systems that we come into contact with every day. It is important to be familiar with different kinds of systems for at least two reasons: First of all, even though your work as a systems analyst will probably focus on one kind of system – an automated, computerized information system – it will generally be a part of a larger system. Thus, to make your system successful, you must understand the other systems with which it will interact. Many of the computer systems that we build are replacements, or new implementations of, non-computerized systems that are already in existence. Also, most computer systems interact with, or interface with, a variety of existing systems (some of which may be computerized and some which may not). If our new computer system is to be successful, we must understand, in reasonable detail, how the current system behaves. Second, even though many types of systems appear to be quite different, they turn out to have many similarities. There are common principles and philosophies and theories that apply remarkably well to virtually all kinds of systems. And now, we can consider a definition of the basic term "system". It provides several definitions: 1. A regularly interacting or interdependent group of items forming a unified whole. 2. An organized set of doctrines, ideas, or principles, usually intended to explain the arrangements or working of a systematic whole. 3. An organized or established procedure. 4. Harmonious arrangement or pattern: order. 5. An organized society or social situation regarded as non-stultifying establishment. COMMON TYPE OF SYSTEMS There are many different types of systems, but indeed, virtually everything that we come into contact with during our day-to-day life is either a system or a component of a system (both). It is useful to organize the many different kinds of systems into useful categories. Because our ultimate focus is on computer systems, we will divide all systems into two categories: natural systems and man-made systems. NATURAL SYSTEMS There are a lot of systems that are not made by people: they exist in nature and, by and large, serve their own purpose. It is convenient to divide natural systems into two basic subcategories: physical systems and living systems. Physical Systems include such diverse example as: Stellar systems: galaxies, solar systems, and so on. Geological systems: rivers, mountain ranges, and so on. Molecular systems: complex organizations of atoms. Living systems Living systems encompass all of the myriad animals and plants around us, as well as our own human race. The properties and characteristics of familiar living systems can be used to help illustrate and better understand man-made systems. 19 properties and characteristics of familiar LIVING SYSTEMS can be used to help illustrate and better understand MAN-MADE SYSTEMS 1. The reproducer, which is capable of giving rise to other systems similar to the one it is in. 2. The boundary, which holds together the components that make up the system, protects them from environmental stresses, and excludes or permits entry to various sorts of matter-energy and information. 3. The ingestor, which brings matter-energy across the system boundary from its environment. 4. The distributor, which carries inputs from outside the system or outputs from its subsystems around the system to each component. 5. The converter, which changes certain inputs to the system into forms more useful for the special processes of that particular system. 6. The producer, which forms stable associations that endure for significant periods among matter-energy inputs to the system or outputs from its converter, the materials synthesized being or growth, damage repair, or replacement of components of the system, or for providing energy for moving or constituting the system’s outputs of products or information markets to its suprasystem. 7. The matter-energy storage subsystem, which retains in the system, for different periods of time, deposits of various sorts of matter-energy. 8. The extruder, which transmits matter-energy out of the system in the form of products or wastes. 9. The motor, which moves the system or parts of it in relation to part or all of its environment or moves components of its environment in relation to each other. 10. The supporter, which maintains the proper spatial relationships among components of the systems, so that they can interact without weighing each other down or crowding each other. 11. The input transducer, which brings markers bearing information into system, changing them to other matter-energy forms suitable for transmission within it. 12. The internal transducer, which receives, from other subsystems or components within the system, markers bearing information about significant alterations in those subsystems or components, changing them to other matter-energy form of a sort that can be transmitted within it. 13. The channel and net, which are composed of a single route in physical space, or multiple interconnected routes, by which markers bearing information are transmitted to all parts of the system 14. The decoder, who alters the code of information input to it through the input transducer or internal transducer into a private code that can be used internally by the system. 15. The associator, which carries out the first stage of the learning process, forming enduring associations among items of information in the system. 16. The memory, which carries out the second stage of the learning process, storing various sorts of information in the system for different periods of time. 17. The decider, which receives information inputs from all other subsystems and transmits to them information outputs that control the entire system. 18. The encoder, who alters the code of information input to it from other information processing subsystems, from a private code used internally by the system into a public code that can be interpreted by other systems in its environment. 19. The output transducer, which puts out markers bearing information from the system, changing markers within the system into other matter-energy forms that can be transmitted over channels in the system’s environment. Keep in mind that many man-made systems (and automated systems) interact with living systems. In some cases, automated systems are being designed to replace living systems. And in other cases, researchers are considering living systems as components of automated systems MAN-MADE SYSTEMS Man-made systems include such things as: 1. Social systems: organizations of laws, doctrines, customs, and so on. 2. An organized, disciplined collection of ideas. 3. Transportation systems: networks of highways, canals, airlines and so on. 4. Communication systems: telephone, telex, and so on. 5. Manufacturing systems: factories, assembly lines, and so on. 6. Financial systems: accounting, inventory, general ledger and so on. Most of these systems include computers today. As a systems analyst, you will naturally assume that every system that you come in contact with should be computerized. And the customer or user, with whom you interact will generally assume that you have such a bias. A systems analyst will analyze, or study, the system to determine its essence: and understand the system's required behavior, independent of the technology used to implement the system. In most case, we will be in a position to determine whether it makes sense to use a computer to carry out the functions of the system only after modeling its essential behaviour. Some information processing systems may not be automated because of these common reasons: Cost; Convenience; Security; Maintainability; Politics. Automated Systems Automated systems are the man-made systems that interact with or are controlled by one or more computers. We can distinguish many different kinds of automated systems, but they all tend to have common components: 1. Computer hardware (CPUs, disks, terminals, and so on). 2. Computer software: system programs such as operating systems, database systems, and so on. 3. Peopleware/Warmware: those who operate the system, those who provide its inputs and consume its outputs, and those who provide manual processing activities in a system. 4. Data: the information that the system remembers over a period of time. 5. Procedures: formal policies and instructions for operating the system. One way of categorizing automated systems is by application. However, this turns out not to be terribly useful, for the techniques that we will discuss for analyzing, modeling, designing, and implementing automated systems are generally the same regardless of the application. A more useful categorization of automated systems 1. Batch system: A batch system is one which in it, the information is usually retrieved on a sequential basis, which means that the computer system read through all the records in its database, processing and updating those records for which there is some activity. 2. A real-time system may be defined as one which controls an environment by receiving data, processing them, and returning the results sufficiently quickly to affect the environment at that time. Immediacy of data processing: The time in which a computer system processes and updates data as soon as it is received from some external source such as an air-traffic control or antilock brake system. The time available to receive the data, process it, and respond to the external process is dictated by the time constraints imposed by the process. A real time system must satisfy the requirements of producing the desired results immediately or at a particular time. They process data so quickly that the results of the processes are available to influence activities that are currently taking place. Examples include, air – line ticket reservation systems, low level entry billing systems, and so on. 3.On-line systems: An on-line system is one which accepts input directly from the area where it is created. It is also a system in which the outputs, or results of computation, are returned directly to where they are required. 4. Decision-support systems: These computer systems do not make decisions on their own, but instead help managers and other professional “knowledge workers” in an organization make intelligent, informed decisions about various aspects of the operation Typically, the decision-support systems are passive in the sense that they do not operate on a regular basis: instead, they are used on an ad hoc basis, whenever needed. 5. Knowledge-based systems: The goal of computer scientists working in the field of artificial intelligence is to produce programs that imitate human performance in a wide variety of “intelligent” tasks. For some expert systems, that goal is close to being attained. For others, although we do not yet know how to construct programs that perform well on their own, we can begin to build programs that significantly assist people in their performance of a task. General Systems Principles There are a few general principles that are of particular interest to people building automated information systems. They include the following: 1. The more specialized a system is, the less able it is to adapt to different circumstances. 2. The more general-purpose a system is, the less optimized it is for any particular situation. But the more the system is optimized for a particular situation, the less adaptable it will be to new circumstances. 3. The larger a system is, the more of its resources that must be devoted to its everyday maintenance. 4. Systems are always part of larger systems, and they can always be partitioned into smaller systems. 5. Systems grow. This principle could not be true for all systems, but many of the systems with which we are familiar do grow, because we often fail to take it into account when we begin developing the system. Computing in the Early Days Some people have phobia for computers. But computers are merely machines, made by people, meant to be used by people and capable of being understood by people Some say that a computer is a “Thinking Machine”. The “Thinking Machine” could be a devious machine; hatching plots against you as you sit on your desk, thinking of evil deeds that will cause you endless frustration. But a computer neither has emotions nor motivations. It is simply an Electronic Device. In the earlier days of computing, when very few people had access to the computer, those who use computers were thought to be wizards, being able to communicate with them. It is true that proficient use of earlier computers involves the memorizing of long sentences of computer codes, but all modern computers, especially the personal computers, are designed to make working with them hassle free. Computers are now made to be ‘friendly’ with anyone attempting to use them  Basic Components of a Computer System Other definition:- A machine that can be programmed to accept data (input), process it into useful information (output), and store it away (in secondary storage device) for safekeeping or later reuse Process is directed by software but performed by the hardware Cornerstones of our Economy Forging a Computer-Based Society: Land Labor Capital Information Jobs Forging a Computer-Based Society: From physical to mental From muscle-power to brain-power COMPONENTS OF INFORMATION TECHNOLOGY Hardware Software Warmware/People Procedures Data  What is a Computer? A general-purpose machine that processes data according to a set of instructions that are stored internally either temporarily or permanently. The computer and all equipment attached to it are called hardware. The instructions that tell it what to do are called software. WHAT IS COMPUTER? A Computer is: 1. An Electronic device that can 2. Accept data (as input) 3. Process it 4. Gives the result (as output) 5. Stores processed data (as information) for future or further use. 30 Computer Systems are the same Data is INPUT Data is PROCESSED Something is OUTPUT GIGO (Garbage in…Garbage out..) Generations of Computers The technological advancements in the development of computers are classified into distinct groups often referred to as the Computer Generations 1. The first generation is characterized by vacuum tubes or the thermionic valves. These tubes made the computer to be unnecessarily big, dissipates a lot of energy and very slow. Examples are ENIAC (which used 18,000 vacuum tubes), EDVAC and UNIVAC..... 2. The development of electronic transistors gave birth to the second generation of computers, as tubes were replaced by transistors in the construction of the computer. Hence, these computers were smaller in size, generated much less heat, faster, cost less and more reliable. Examples are Honeywell 800, IBM, etc. 3. The introduction of integrated circuits (IC) into the manufacturing of computers led to the third generation of computers..... An integrated circuit (IC) consists of many circuit elements such as transistors and resistors fabricated on a single piece of silicon or other semiconducting material or an integrated circuit (IC) contains thousands of switches arranged on circuit boards small enough to be hidden by your fingertip. These became known as Chips. Hence with this advance in technology, computers of this generation are lighter in weight, faster, more reliable and of course cost less, e.g. IBM/360; which was introduced in 1964..... The tiny microprocessor shown here is the heart of the personal computer (PC). Such devices may contain several million transistors and be able to execute over 100 million instructions per second. The rows of leglike metal pins are used to connect the microprocessor to a circuit board.... 4. Further improvement on the degree of integration led to the fourth generation. This generation is characterized by the use of Large Scale Integration (LSI), meaning many components in a very small space. This further led to the reduction of physical size/components of the computer e.g. pocket calculators, digital watches, and some personal computers. 5. The advanced industrial robots are classified in the fifth generation. This generation is concentrating on the way computers are used, not on the electronic refinement that characterized the previous four. Generations of Computers Rather than processors of data, computer programs called Expert Systems are widely used. Neural Networks Research in Artificial Intelligence – Artificial Intelligent computers will require memory capacities more than that which can accommodate up to 400 million characters, a memory space enough to store the name and address of over 4 million people. Artificial Intelligence computers tap into data storage devices thousands of times larger than those available to any microcomputer, and they are called Monster Computers. Currently, researchers have perfected microcomputer storage devices that can store up to three billion characters – enough room to store the names and addresses of 30 million people INPUT DEVICES Input devices are the components of computer which are used to input or give data and instruction to the computer by the user. The input unit is responsible for taking input and converting it into computer understandable language(binary code) Data Vs Instruction 2+2=4 Informatio DATA Instruction n For example Keyboard, Mouse, Mic, Scanner, Camera, etc. 38 Types of Input Devices Key Board Keyboard is the type of input device which is used to give data and instruction with the help of some sort of keys (AlphaNumeric, Numeric keypad, Special, and Function keys.) to the computer by the user. Types of key board Devoke (Enhanced) QWERTY (Standard) 39 Types of Input Devices Pointing Devices Pointing Devices are those device which are used to give data, instruction and point out some specific of a specific graph. Types of Pointing Devices Mouse (Mechanical, Optical) Pointing Pen Touch Pad Pointing Stick Joy Stick 40 Types of Input Devices Optical Devices Optical devices are used to give data in the shape of image. Types of Optical Devices Digital Camera Scanner MICR OCR 41  Types of Input Devices Sound Devices Sound Devices are used to give data to the computer in the shape of vice. Types of Sound Devices Microphone Mic 42 All Examples of? INPUT DEVICES PROCESSING DEVICE: The Central Processing Unit (CPU) Processing devices are also the components of computer which are used to process the data and convert into information. The CPU is the control centre of the computer, as it guides, directs and governs its performance. It is the brain of the computer. The CPU has three components which are responsible for different functions. They are: Control unit (CU) Arithmetic Logical Unit (ALU) Memory Unit (Main memory, Registers, Cache memory, BUSES CPU: CONTROL UNIT (CU) It is responsible for directing and coordinating most of the computer system activities. It does not execute instructions by itself. It tells other parts of the computer system what to do. It determines the movement of electronic signals between the main memory and arithmetic logic unit as well as the control signals between the CPU and input/output devices. CPU: Arithmetic and Logic Unit (ALU) ALU performs all the arithmetic and logical functions i.e. addition, subtraction, multiplication, division and certain comparisons. These comparisons include greater than, less than, equals to etc. The ALU controls the speed of calculations. CPU: Registers It is a special temporary storage location within the CPU. Registers quickly, accept, store and transfer data and instructions that are being used immediately (main memory hold data that will be used shortly, secondary storage holds data that will be used later). To execute an instruction, the control unit of the CPU retrieves it from main memory and places it onto a register. The typical operations that take place in the processing of instruction are part of the instruction cycle or execution cycle. The instruction cycle refers to the retrieval of the instruction from main memory and its subsequence at decoding. The process alerts the circuits in CPU to perform the specified operation. CPU: BUSES The term Bus refers to an electrical pathway through which bits are transmitted between the various computer components. Depending on the design of the system, several types of buses may be present. Types of Computer BUS 1. Data Bus The electrical path through which data is transferred between/among components of the computer CPU: BUSES 2. Address Bus Each component is assigned a unique ID, this ID is called the address of that component. components communicate and locate other component with this bus. 3. Control Bus Control bus is used to transmit different commands from one component to another component, i.e. CPU wants to read data from main memory, it use control bus for giving commands.  CPU: BUSES 4. Expansion Bus The expansion bus allows the processor to communicate with the peripheral devices attached to the card. Types of Expansion Bus ISA (Industry Standard Architecture) Bus Local/PCI (Peripheral Component Interface) Bus AGP (Accelerated Graphics Port) Bus 50 Processor Brain of the computer Processes instructions THREE STEPS 1) Fetches Instructions 2) Decodes Instruction 3) Executes Instruction Either chips or integrated circuits Integrated circuits are also found in almost every modern electrical device such as cars, television sets, CD players, cellular phones, etc. What is a Processor? Most computers use integrated chips….or integrated circuits for their processors or main memory A chip is about 1cm square…and can hold MILLIONS of electronic components such as transistors and resistors CPU of a microcomputer is a microprocessor Processor and MAIN MEMORY of a PC are held on a single board called a motherboard. MEMORY Memory means the ability of computer to store the data on temporary or permanent basis. Types of Memory 1. Primary Memory It is the type of computer memory which has capability to store data temporarily. It is also called volatile memory. 2. Secondary Memory It is the type of computer memory which has capability to store data on permanent basis. It is also called non-volatile memory. 53 Primary Vs Secondary MemoryRAM Primary Memory INPUT MAIN MEMORY OUT PUT CPU ALU CU RANDOM ACCESS MEMORY 54 MAIN MEMORY The main memory of the computer is also known as the primary memory. It is like a predefined working place, where it temporarily keeps information and data to facilitate its performance. When the task is performed, it clears its memory and memory space and is then available for the next task to be performed. When the power is switched off, everything stored in the memory gets erased and cannot be recalled. There are two types of primary (main) memory which are as follows: 1. Random Access Memory (RAM) 2. Read Only Memory (ROM) PRIMARY MEMORY: RAM and ROM There are two kinds of Memory 1. RAM –Random Access Memory (MM) – This is used for storing programs that are currently running and data that is being processed. 2. ROM –Read Only Memory – Its contents are PERMANENTLY etched into the memory chip at the manufacturing stage. It is used – for example – to load the bootstrap loader (the program that loads as soon as you start the machine) RAM – Random Access memory Stores info about applications that are open and data VOLATILE – When you switch off the machine, it disappears!!! TYPES OF RAM S-RAM (Static Random Access Memory) 1. Low cost 2. Low Speed Refresh again and again D-RAM (Dynamic Random Access Memory) 1. Costly 2. High Speed 3. Automatic Refresh System TYPES DRAM OF- Dynamic RAMRandom Access Memory SRAM - Static Random Access Memory SDRAM - Synchronous dynamic RAM DDRAM - Double Data RAM SIMM - Single In-line Memory Module DIMM - Dual In-line Memory Module EDO-DRAM - Extended Data Out Dynamic RAM DDR SDRAM - Double Data Rate Synchronous Dynamic RAM FPM DRAM - Fast Page Mode Dynamic RAM RD-RAM – Rambus Dynamic RAM D-RDRAM - Direct Rambus Dynamic Random Access Memory MDRAM – Multibank Dynamic Random Access Memory BEDO-DRAM – Burst Extended Data Out Dynamic RAM DDR-DRAM – Double Data Rate Direct RAM 58 ROM – Read Only Memory Non-Volatile (does not change) Programs that are necessary for the computer to run like the Boot up program (BIOS) KINDS OF ROM PROM (Programmable Read Only Memory) only one time EPROM (ELECTRONICALLY (erasable) Programmable Read Only Memory) Two or three time EEPROM (Electronic Erasable Programmable Read Only Memory) Flash Memory again and again MAIN MEMORY The program currently being executed and the data used by the program is held in MAIN MEMORY MM is divided into millions of individually addressable storage units called BYTES One byte can hold one character Or one byte can hold a code representing something –i.e a part of a picture, or a sound, or a program instruction. The total number of bytes in MM = The computers MEMORY SIZE. STORAGE DEVICES Storage Devices are used to store data on permanent or temporary basis. Types of Storage Devices Magnetic Devices 1. Magnetic Tape 2. Hard Disk 3. Floppy Disk Optical Devices 1. CD-ROM, CD-RW 2. DVD-ROM, DVD-RW 61 Disk Storage Auxiliary storage is also called SECONDARY MEMORY BACKING STORE EXTERNAL MEMORY The most common secondary memory (auxiliary storage) is DISK! Other types of storage include Flash Memory Cards, Sticks, Floppy discs etc. Secondary Storage It is needed because Main memory stores data temporarily Main memory space is limited Benefits of secondary storage Space Reliability Convenience Economic  Storage Devices Many different consumer electronic devices can store data. Edison cylinder phonograph ca. 1899. The Phonograph cylinder is a storage medium. The phonograph may or may not be considered a storage device. Output Devices Output units gives out or display information for us to see and use. Display monitors: Hi-resolution monitors come in two types: Cathode ray tube (CRT) - Streams of electrons make phosphors glow on a large vacuum tube. Liquid crystal display (LCD) - A flat panel display that uses crystals to let varying amounts of different colored light to pass through it. Developed primarily for portable computers. Types of Output Devices Display Device Display devices are used to get result/information from the computer in Soft Copy. Monitor Monitor is an output device which gives the result/information in text, images, video, or any other format. 67 Types of Monitor According to Technology CRT (Cathode Ray Tube) 68 Types of Monitor According to Technology LCD (Liquid Crystal Display) Liquid Material between two layers of Glass 69 Types of Monitor According to Technology Gas Plasma Neon Oxen LED – Light Emitting Diodes 70 Types of Monitor According to Size 14” 15” 17” 19” 21” diagonal shape measurement 71 Types of Monitor According to Colors Monochromes which contains only one color on its background Gray Scale Monitor it contains only two colors one is black and the other is White Color Monitor it contains 16~16 million colors (16,777,216 possible colors) High Resolution Costly 72 Output Devices Audio Output Devices Windows machines need special audio card for audio output. Audio output is useful for: Music CD player is a computer. Most personal computers have CD players that can access both music CDs and CD-ROMs. Voice synthesis (becoming more human sounding.) Multimedia Printer Printer is the type of output device which is used to get the result/information in the shape of hardcopy from the computer. Types of Printer 1. Impact Printer It prints characters or images by striking. E.g. Dot Matrix Printer Line Printer Daisy Wheel Printer 74 Printer 2. Non-Impact Printer A non-impact printer prints characters and graphs on a piece of paper without striking. Types of Non-Impact Printer 1. Inkjet Printer 2. LASER (Light Amplification by Stimulated Emission of Radiation) 3. Thermal Printer 4. Photo Printer Plotter 75 Optical Devices Examples include: 1. Projectors (Projector:- An optical device that projects or casts a beam of light of images unto a screen), 2. Holograms (Holography:- A technique in physics for recording and then reconstructing the amplitude and phase distributions of a coherent wave disturbance; used to produce three-dimensional images), etc. Computer Structure Processor Architecture / Fabrication / Operation Hardware (in Computer) has to do with the equipments involved in the proper functioning of a computer. Computer hardware consists of the components that can be physically handled. The function of these components is typically divided into three main categories: input, output, and storage. Components in these categories connect to microprocessors, specifically, the computer’s central processing unit (CPU), the electronic circuitry that provides the computational ability and control of the computer, via wires or circuitry called a bus. Computer System A typical computer system consists of a central processing unit (CPU), input devices, storage devices, and output devices. The CPU consists of an arithmetic/logic unit, registers, control section, and internal bus. The arithmetic/logic unit carries out arithmetical and logical operations. The registers store data and keep track of operations. The control unit regulates and controls various operations. The internal bus connects the units of the CPU with each other and with external components of the system. For most computers, the principal input devices are a keyboard and a mouse. Storage devices include hard disks, CD-ROM drives, and random access memory (RAM) chips. Output devices that display data include monitors and printers. Cont. > > > > Software, on the other hand, is the set of instructions a computer uses to manipulate data, such as a word-processing program or a video game. These programs are usually stored and transferred via the computer's hardware to and from the CPU. Software also governs how the hardware is utilized; for example, how information is retrieved from a storage device. The interaction between the input and output hardware is controlled by software called the Basic Input Output System software (BIOS). Although microprocessors are still technically considered to be hardware, portions of their function are also associated with computer software. Since microprocessors have both hardware and software aspects they are therefore often referred to as firmware. The Computer Chipset The various components of a computer communicate with each other through a chipset, which is a collection of microprocessors connected to each other through a series of wires (also called Buses). Shown here is a diagram of a typical chipset, displaying the computer’s components and how they are connected to each other. ` Introduction to System Analysis and Design The key to success in business is the ability to gather, organize, and interpret information. Systems analysis and design is a proven methodology that helps both large and small businesses reap the rewards of utilizing information to its full capacity. The person in the organization most involved with systems analysis and design is the systems analyst SYSTEM LIFE CYCLE System life cycle is an organisational process of developing and maintaining systems. It helps in establishing a system project plan, because it gives overall list of processes and sub-processes required developing a system. System development life cycle means combination of various activities. In other words we can say that various activities put together are referred as system development life cycle. In the System Analysis and Design terminology, the system development life cycle means software development life cycle 8-phase SDLC Following are the different phases of software development cycle: System study Feasibility study System analysis System design Coding Testing Implementation Maintenance The different phases of software development life cycle is shown in fig 1 Fig. 1 Different phases of Software development Life Cycle PHASES OF SYSTEM DEVELOPMENT LIFE CYCLE Let us now describe the different phases and the related activities of system development life cycle in detail. (a) System Study System study is the first stage of system development life cycle. This gives a clear picture of what actually the physical system is. In practice, the system study is done in two phases. In the first phase, the preliminary survey of the system is done which helps in identifying the scope of the system. The second phase of the system study is more detailed and in-depth study in which the identification of user’s requirement and the limitations and problems of the present system are studied. After completing the system study, a system proposal is prepared by the System Analyst (who studies the system) and placed before the user. The proposed system contains the findings of the present system and recommendations to overcome the limitations and problems of the present system in the light of the user’s requirements. To describe the system study phase more analytically, we would say that system study phase passes through the following steps: problem identification and project initiation background analysis inference or findings (b) Feasibility Study On the basis of result of the initial study, feasibility study takes place. The feasibility study is basically the test of the proposed system in the light of its workability, meeting user’s requirements, effective use of resources and.of course, the cost effectiveness. The main goal of feasibility study is not to solve the problem but to achieve the scope. In the process of feasibility study, the cost and benefits are estimated with greater accuracy. (c) System Analysis Assuming that a new system is to be developed, the next phase is system analysis. Analysis involved a detailed study of the current system, leading to specifications of a new system. Analysis is a detailed study of various operations performed by a system and their relationships within and outside the system. During analysis, data are collected on the available files, decision points and transactions handled by the present system. Interviews, on-site observation and questionnaire are the tools used for system analysis. Using the following steps it becomes easy to draw the exact boundary of the new system under consideration: Keeping in view the problems and new requirements Workout the pros and cons including new areas of the system  All procedures, requirements that must be analysed are documented in the form of detailed data flow diagrams (DFDs), data dictionary, logical data structures and miniature specifications. System Analysis also includes sub-dividing of complex process involving the entire system, identification of data store and manual processes. The main points to be discussed in system analysis are: Specification of what the new system is to accomplish based on the user requirements. Functional hierarchy showing the functions to be performed by the new system and their relationship with each other. Function network which is similar to function hierarchy but they highlight the functions which are common to more than one procedure. List of attributes of the entities - these are the data items which need to be held about each entity (record) (d) System Design Based on the user requirements and the detailed analysis of a new system, the new system must be designed. This is the phase of system designing. It is a most crucial phase in the development of a system. Normally, the design proceeds in two stages : preliminary or general design Structure or detailed design Preliminary or general design: In the preliminary or general design, the features of the new system are specified. The costs of implementing these features and the benefits to be derived are estimated. If the project is still considered to be feasible, we move to the detailed design stage. Structure or Detailed design: In the detailed design stage, computer oriented work begins in earnest. At this stage, the design of the system becomes more structured. Structure design is a blue print of a computer system solution to a given problem having the same components and inter-relationship among the same components as the original problem. Input, output and processing specifications are drawn up in detail. In the design stage, the programming language and the platform in which the new system will run are also decided. There are several tools and techniques used for designing. These tools and techniques are: Flowchart Data flow diagram (DFDs) Data dictionary Structured English Decision table Decision tree Each of the above tools for designing will be discussed in detailed later (e) Coding After designing the new system, the whole system is required to be converted into computer understanding language. Coding the new system into computer programming language does this. It is an important stage where the defined procedure are transformed into control specifications by the help of a computer language. This is also called the programming phase in which the programmer converts the program specifications into computer instructions, which we refer as programs. The programs coordinate the data movements and control the entire process in a system. It is generally felt that the programs must be modular in nature. This helps in fast development, easy maintenance and future change, if required. (f) Testing Before actually implementing the new system into operations, a test run of the system is done removing all the bugs, if any. It is an important phase of a successful system. After codifying the whole programs of the system, a test plan should be developed and run on a given set of test data. The output of the test run should match the expected results. Using the test data following test run are carried out: Unit test System test Unit test: When the programs have been coded and compiled and brought to working conditions, they must be individually tested with the prepared test data. Any undesirable happening must be noted and debugged (error corrections). System Test: After carrying out the unit test for each of the programs of the system and when errors are removed, then system test is done. At this stage the test is done on actual data. The complete system is executed on the actual data. At each stage of the execution, the results or output of the system is analysed. During the result analysis, it may be found that the outputs are not matching the expected output of the system. In such case, the errors in the particular programs are identified and are fixed and further tested for the expected output. When it is ensured that the system is running error-free, the users are called with their own actual data so that the system could be shown running as per their requirements. (g) Implementation After having the user acceptance of the new system developed, the implementation phase begins. Implementation is the stage of a project during which theory is turned into practice. During this phase, all the programs of the system are loaded onto the user's computer. After loading the system, training of the users starts. Main topics of such type of training are: How to execute the package How to enter the data How to process the data (processing details) How to take out the reports After the users are trained about the computerised system, manual working has to shift from manual to computerised working. The following two strategies are followed for running the system: Parallel run: In such run for a certain defined period, both the systems i.e. computerised and manual are executed in parallel. This strategy is helpful because of the following: Manual results can be compared with the results of the computerised system.  Failure of the computerised system at the early stage, does not affect the working of the organisation, because the manual system continues to work, as it used to do. Pilot run: In this type of run, the new system is installed in parts. Some part of the new system is installed first and executed successfully for considerable time period. When the results are found satisfactory then only other parts are implemented. This strategy builds the confidence and the errors are traced easily. (h) Maintenance Maintenance is necessary to eliminate errors in the system during its working life and to tune the system to any variations in its working environment. It has been seen that there are always some errors found in the system that must be noted and corrected. It also means the review of the system from time to time. The review of the system is done for: knowing the full capabilities of the system knowing the required changes or the additional requirements studying the performance If a major change to a system is needed, a new project may have to be set up to carry out the change. The new project will then proceed through all the above life cycle phases. PRINCIPLES OF MODELING OBJECTIVES IN THE MODELING OF SYSTEMS Much scientific and engineering works include the formulation of knowledge and the building of models. From experiments and observations, one can form abstract representations and laws which can then provide a basis for analysis or engineering designs. 1. MATHEMATICAL MODELING: Mathematical models are one particular type of abstract representation which has been found to provide a very effective means of encoding information about a real system. OBJECTIVES IN THE MODELING OF SYSTEMS: MATHEMATICAL MODELING A mathematical model which embraces the essential features of a real world system, permits useful analysis to be carried out for the range of conditions for which the model is believed to be accurate and useful. The acceptability of mathematical modeling and the extent to which modeling techniques are used, varies considerably from one field to another. Often, it is when students are exposed to more advanced experimental works in these fields that they begin to appreciate some of the limitations of the models which they are using. OBJECTIVES IN THE MODELING OF SYSTEMS: MATHEMATICAL MODELING However, in the biological sciences, mathematical modeling is still viewed with some suspicions, although there are many examples in which models are being used very effectively to help solve important biological problems Objectives in the development and application of mathematical models are very dependent upon the subject area. Generally, written pure science mathematical models are developed for one or more of the following reasons: 1. Hypothesis testing, 2. The development of new or improved experiments, and OBJECTIVES IN THE MODELING OF SYSTEMS: MATHEMATICAL MODELING 3. The provision of a concise quantitative description which extends the capabilities of the human brain to handle the complexities of the real system under consideration. In this field of application, questions concerning model accuracy and credibility are of central importance, since decisions may be made on the basis of mathematical model predictions which have a direct bearing on the safety, reliability, efficiency or effectiveness of some new products or system. In general, whatever the field of application, mathematical modeling should be seen as just one aspect of the system approach to problem solving. PRINCIPLES OF MODELING 2. SIMULATION MODELING: Despite the impressive advances in mathematical modeling, many real-life situations are still well beyond the capabilities of representing systems mathematically. For one thing, the rigidity of mathematical representations may make it impossible to describe the decision problem by a mathematical model adequately. Alternatively, even when it is plausible to formulate a proper mathematical model, the resulting optimization problem may prove too complex for available solution algorithms. An alternative approach to modeling complex systems is simulation. Simulation modeling is the next best thing to observing a real system. It allows us to collect pertinent information about the behavior of the system by executing a computerized model. The collected data are then used to design the system. OBJECTIVES IN THE MODELING OF SYSTEMS: SIMULATION MODELING Simulation is not an optimization technique; rather, it is a technique for estimating the measure of performance of the modeled system. It differs from mathematical modeling in that, the relationship between the input and output need not be stated explicitly. Instead, it breaks down the real system into (small) modules, and then imitates the actual behavior of the system by using logical relationships to link the modules together. Starting with the input module, the simulation computations moves among the appropriate modules until the output result is realized. OBJECTIVES IN THE MODELING OF SYSTEMS: SIMULATION MODELING Simulation computations, though usually simple, are voluminous. It is thus unthinkable to execute a simulation model without the use of a computer. They are much more flexible in representing systems than their mathematical counterparts. The main reason for this flexibility is that simulation modeling reviews the system at an elemental level, whereas mathematical models tend to represent the system from a more global standpoint. OBJECTIVES IN THE MODELING OF SYSTEMS: SIMULATION MODELING The flexibility of simulation is not without drawbacks: The development of a simulation model is usually costly in both time and resources; moreover, the execution of some simulation models, even on the fastest computers, may be slow ART OF MODELING An Operation Research study must be rooted in teamwork, where both the OR analyst and the client work side by side. The OR analysis with their expertise in modeling will need the experience and cooperation of the client for whom the study is being carried out. ART OF MODELING As a decision making tool, OR must be viewed as both a science and an art. It is a science by virtue of the embodying mathematical techniques it presents, and it is an art because the success of all the phases that precedes and succeeds the solution of the mathematical model depends largely on the creativity and expertise of the OR team. Willemain (1994) advices that “effective [OR] practice requires more than analytical competence: It also requires among other attributes, technical judgment (for example, when and how to use a given techniques) and skills in communication and organization survival”. It is difficult to prescribe specific courses of action (similar to those dictated by the precise theory of mathematical models) for these intangible factors. As such, we would consider the general guidelines for the implementation of OR in precise. ART OF MODELING The principal phases for implementing OR in practice includes: Definition of the problem Construction of the model Solution of the model Validation of the model Implementation of the solution 1. PROBLEM DEFINITION This involves defining the scope of the problem under investigation. This is a function that should be carried out by the entire OR team. ART OF MODELING The end result of the investigation is to identify three principal elements of the decision problem namely: The description of the decision alternatives The determination of the objectives of the study The specification of the limitations under which the modeled system operates 2. MODEL CONSTRUCTION This entails translating the problem definition into mathematical relationships. If the resulting model fits into one of the standard mathematical models, such as linear programming, a situation is usually attainable by using available algorithms. Alternatively, if the mathematical relationships are too complex to allow the determination of an analytic solution, the OR team may opt to simplify the model and use a heuristic approach, or the team may consider the use of simulation, if appropriate. ART OF MODELING In some cases, a combination of mathematical simulation and heuristic modeling may be appropriate for solving the decision problem. 3. MODEL SOLUTION This is the simplest of all OR phases because it entails the use of well – defined optimization algorithms. An important aspect of the model solution phase is sensitivity analysis. It deals with obtaining additional information about the behavior of the optimum solution when the model undergoes some parameter variations. Sensitivity analysis is particularly needed when the parameters of the model cannot be estimated accurately. In this case, it is important to study the behavior of the optimum solution in the neighborhood of the initial estimates of the model’s parameters. 4. MODEL VALIDITY This checks whether of not the proposed system does what it is supposed to do. That is, does the model provide a reasonable prediction of the behavior of the system under study? ART OF MODELING Initially, the OR team should be convinced that the output of the model doesn’t contain element of surprises. In other words, does the solution make sense? Are the results intuitively acceptable? On the formal side, a common method for checking the validity of a model is to compare its output with historical output data. The model is valid, if under similar input conditions, it reproduces past performance. Generally however, there is no assurance that future performance will continue to duplicate past behaviors. Also, because the model is usually based on careful examination of past data, the proposed comparisons should be favorable 5. IMPLEMENTATION OF THE SOLUTION Implementation of the solution of a validated model involves the translation of the model’s results into operating instructions, used in understandable form to the individuals who will administer the recommended system; and the burden of this task lies primarily with the OR team.