unit 2_designing computer based method & procedures control & designing structured programs _5!1!10
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Management Information Systems Unit 2. System Development Designing Computer Based Methods, Procedures Control, Designing Structured Programs.5-1-2010 A Sanjeev raj
Today we are going to discuss about..- Designing Computer Based Methods, Procedures. - Designing System Controls. - Designing Structured Programs.
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Designing Computer Based Methods, Procedures & Controls
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What is to be Designed? Outputs. Inputs. Procedures. Database Interactions: Identifying the requirements of datastorage & Management. for recovery.
Controls: Requirements for Data integrity, security and procedures
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Design Objectives (IRACIS) Increase Revenues (IR). Avoid Costs (AC). Increase Services (IS).The following features give an indication of a good quality design. Functional: It must meet and support the user requirements. Efficient: This aspect may be measured in terms of (1) Throughput (2) Response Time (3) Run Time
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Portable:
Portability closely related to independence of hardware and software platforms.
Secure: Resistant to breach of conduct and privacy. Reliable: System should record all the data accurately andstore into computer without omissions.
Easy to use.
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Output DesignAny output should serve one or more of the following purposes: Should convey into about the past, present or future. Should signal events, opportunities and problems. Should trigger an action as a result of some event. Should confirm an action as a result of transaction.
Objectives of Output Design:
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Output Design Key Points Who will receive the output? What is its Planned use? When and how often is it needed?
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Report #
Name/ Description
User
Planned Use
Frequency
Print/ Display
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Sales Trend Marketing Analysis Manager
Analysis
Monthly
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Presentation of Output Tabular format is preferred when detailed reports are to be presented. Graphical representation improves the effectiveness of the output and depicts the entire data in a small space.
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Output Design Specifications Major Points to be highlighted in design specifications are:1. 2. 3. 4. Size of Paper. Pre printed forms. Multiple Copies. Design Layout.
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Input Design Objectives of the input design: - Keep control on the volume of data being entered. - Avoid processing details during data entry so as to speed up the entry process. - Avoid data entry errors. Layout of input Form: - The heading and date of data entry. - The data columns: Heading and Value. - The data type and length of each data column. - The initials of data entry operator.KVIMIS-MBA0925-MIS 2. Systems Development 12
Input Codification Scheme Some popular schemes of codification are given below: Classification of codes: According to the class of objects e.g., electrical goods classified according to their attributes like fans, lamps, tables, cables as FN, LP, TB, CB, etc.
Sequence Codes: Generation of Automatic Serial Numbers. Mnemonic Codes: Abbreviated form of the completeDescription.
Significant Digit Subset Codes: E.g., Phone no. 0422 260 -5219 City Local exchange Serial No.
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Procedures DesignThe procedures Are the ready reckoners for the designer and the user recording how a job should be done. Serves as a supervisor over operators. Can be used as a training tool for the end users and operators. Assist the management in assessing manpower needs.
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Procedures Documentation It is clear, unambiguous, complete and concise. The procedure manual must have 1. A table of contents for easy reference to specific pages of procedures, illustrations, etc. 2. An explanation of the purpose. 3. Step by step directions for each task. 4. A Description of expected results of each procedure and who will benefit. 5. Quality standards for each procedure. 6. What action to take up if a procedure is not allowed. 7. A Procedure for feedback of users.KVIMIS-MBA0925-MIS 2. Systems Development 15
Database Design A data base is an orderly arrangement of all the records related to each other. The following needs to be done for data base design: 1. Identify all the tables or record types. 2. Identify the columns or fields for each table. 3. Identify the relations between various tables. 4. Identify the data type and length for each field of the tables. 5. Identify the key fields for each table. 6. Normalize the data base to ensure simpler, smaller consistent data structures without redundancy. 7. Document the Database Dictionary.
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Design DocumentationDesign Document contains comprehensive details of all the phases of design having the following formation: 1. Brief introduction to the system. 2. Design Factors. 3. Design Constraints. 4. List of Programs. 5. List of Data files. 6. List of input forms. 7. List of outputs. 8. Manual Procedures. 9. Program Specifications. 10. Input/output Specifications.KVIMIS-MBA0925-MIS 2. Systems Development 17
User Manual should contain all the information the user needs to use a system. The manual should be simple, easy to read w/o any technical jargon and should contain. 1. An overview of the system in terms of a flowchart. 2. Clear formats and instructions to fill in the input form. 3. The outputs of the system with report and screen layouts and also with the procedure to retrieve them. 4. Anticipated exceptions that are to be handled by the users. Operational Manual is written for the computer operators. It should contain A Scheme of execution of program. An overview of the system from the operators point of view. This should specify the start, stop and restart sequences. A Scheme for System Maintenance.
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Designing System Controls
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Importance of Controls for Computer IS Huge volumes of data increases potential for errors and so prevent them. Data are in forms not human readable; controls needed to assure stored information is still accessible and accurate. To check data processing accuracy and integrity. To Safeguard corporate assets from both accidental errors and purposeful manipulation.
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INPUT/OUTPUT Processing ControlsInput Control: Checking the data Format checks. Range checks. Sequence checks. Consistency checks. Record and item counts. Flag Fields. Code Design.
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Processing Controls:1. 2. 3. These are concerned with the manipulation of data inside a CPU. For the purpose of organization, consider these under these 4 heads: Control totals. File Processing Controls. Internal data manipulation controls, and computer program controls. The use of check digits on predetermined Nos. The use of Batch Totals. Creation of Journals and Audit Trails for Online.
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Output Control Two major output controls are (1) Tape and Disk Output controls and (2) Printed Output Controls. System Maintenance Control. Monitoring Computer Access and Usage. Protecting Users from each other. Access and Movement Control. Protecting remote transfer of data by providing Password. Catalogue of eligible users.
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Software Controls by providing1. 2. 3. 4. Passwords. Lockout and Dial back systems. Account Nos. Encryption
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Designing Structured Programs
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Steps in Computer Program Development Define the functions of the program. Plan the logic of the program. Code the program. Test and Debug the program. Complete the documentation. Program Planning: The logic to be used to solve the problem is developed algorithms , computer programs, logic flowcharts and structure charts are useful tools. Algorithms Set of rules used to accomplish tasks.
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Coding:
It is the actual writing of computer instructions which will be translated to machine code and followed by computer For this several programming languages particularly COBOL, PL/I are commonly used to solve business Problems.
Testing and Debugging:
A program involve (1) translating a code program into machine language, a process called compilation ; and (2) testing the translated program with sample data and checking the result. If the result of testing is not correct the program is said to have bugs. Debugging is the process of correcting computer programs to obtain correct results. It is derived from every one of
Completion of Documentation:the five steps mentioned above.
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Structured programs are made up of combinations of only four logical structures:1. Sequence Where instructions are executed in the sequence they are coded. 2. If Then Else The Decision structure that states a condition and then what should be done. 3. Iteration (Looping) The structure that causes a module to be repeated. 4. Case A selection structure that allows for the execution of one of several modules, depending upon a data element value.
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Major Advantages Initial development time and cost of the program is less because even complex program are easier to code, test, and Debug than non structured programs. The time and costs associated with modifying a structured program are less because the program logic is easier to understand and update.
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Overview- Designing Computer Based Procedures. - Designing System Controls. - Designing Structured Programs. Thank You. Methods,
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