LESSON 2 SYSTEM ANALYSIS & DESIGN PHASE System Analyst study the requirements and draft the design using design tools Design tools used are system run chart, data flow diagram (DFD) and the data dictionary These charts and diagrams provide a basis for program specification preparation We shall look into the details of how system run chart, data flow diagram (DFD) and the data dictionary are used
System Run Chart A system run chart is a diagram showing an overview of a complete system Pictorial representation of the logical interrelationship between the system using the data processing concept
System Run Chart It will show Tasks carried out in the new system, whether MANUAL or by the COMPUTER Device (disc, tape, drives, terminals, etc) used in the system Media used for input, storage and output Files used by the system
System Run Chart Case Study At the end of each month, ICS Pte Ltd. will run a Payroll program to produce a coinage analysis report so as to prepare the pay packet for each of the employee. All transaction data are stored in the payment transaction file. To ensure that there is no error, the data has to be validated. Validated payment transaction file is then produced. The file is then used to update the payment master file. The payment master file will be used as the input to the coinage analysis program to produce the required report. The validation and updating process will also produce their respective reports.
System Run Chart for Payroll System
System Flow Chart Describe in outline of events in system Show departments, function event & responsibility of each Column format Symbols connected by lines/arrows Plain language annotation
NCC SYMBOLS FOR FLOWCHARTS
DATA FLOW DIAGRAM Also called DFD Tool for recording SA process Users usually don’t understand whole system but only have an in-depth knowledge on part of the system Presentation in DFD will allow the users to understand the full system in detail Diagrammatic representation of the flow of data through a process/system or subprocess/subsystem Shows what happens to the data as it goes through a process
Standard Symbols Used In Data Flow Diagram (DFD) DFD shows Sources & destinations of the data/information Data flow depicted by their names Data store where data/information are stored Processes involved in the system
Standard DFD (Yourdon) Symbols Used Are Source & destination Data flow Data store Process
Case Study The university of Zukota, located in central Africa, offers training courses in computer applications development. Following is a brief description of the admission process for these training courses. Applications for courses have to be sent to the University’s training department. Applications should contain personal details, training course(s) desired and (intended) donor name. The training department’s staff stores the application details after some verification, and sends a letter of acceptance to the applicant and a letter of intimation to the respective donor. On receipt of the donor’s confirmation, a Visa letter is then issued to the applicants.
Data Flow Diagram
Data Flow Diagram
Data Dictionary Data Dictionary (DD) is used to document all data flows, data stores, process and sources/destinations of the data in the system Either manual or automated system Contain information:- Data name -The name of the data item Data description - A brief description of the data item Aliases - Is the data referred by another name? Data type - The data type of the data item Length - The size of the data item Data Values - Permissible values that can be stored Used in - Which process(es) uses it
Data Dictionary As an example, STOCK NO, will have the following details recorded. Data name - STOCK NO Data description - A unique number that identify each stock item Aliases - ITEM-NUMBER Data type - Character Length - 5 Data Values - 10000-99999 Used in - Data-entry-process Check-stock-no-process Update-master-process