Ais Romney 2006 Slides 20 System Design

C HAPTER 20 Systems Design, Implementation, and Operation

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INTRODUCTION • Questions to be addressed in this chapter include: – What are the activities that take place in the conceptual design phase of the systems development life cycle (SDLC)? – What activities take place in the physical systems design phase? – What happens during the systems implementation and conversion process? – What activities occur in the systems operation and maintenance process? © 2006 Prentice Hall Business Publishing

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INTRODUCTION • Accountants must understand the entire systems development process, since they are involved in several ways: – Helping to specify their needs. – As members of the development team. – As auditors after the fact.

• Accountants also help keep the project on track by: – Evaluating and measuring benefits. – Measuring costs. – Ensuring the project stays on schedule. © 2006 Prentice Hall Business Publishing

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INTRODUCTION • Effective systems analysis and design can ensure that developers: – Correctly define the business problem. – Design the appropriate solution.

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INTRODUCTION • The crucial phases of the SDLC include: – Systems analysis to define the new systems requirements (discussed in Chapter 18). – The phases discussed in this chapter, which include: • • • •

Conceptual systems design Physical systems design Systems implementation and conversion Operation and maintenance

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INTRODUCTION • The crucial phases of the SDLC include: – Systems analysis to define the new systems requirements (discussed in Chapter 18). – The phases discussed in this chapter, which include: • • • •

Conceptual systems design Physical systems design Systems implementation and conversion Operation and maintenance

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CONCEPTUAL SYSTEMS DESIGN • In the conceptual systems design phase, a general framework is created for implementing user requirements and solving the problems identified in the analysis phase. • The three main steps are: – Evaluate design alternatives. – Prepare design specifications. – Prepare the conceptual systems design report. © 2006 Prentice Hall Business Publishing

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Conceptual Systems Design Evaluate Design Alternatives

Systems Analysis

Prepare Design Specifications

Prepare Conceptual Systems Design report

Physical Design

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Systems Analysis

Evaluate Design Alternatives

Prepare Design Specifications

Prepare Conceptual Systems Design report

Physical Design

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CONCEPTUAL SYSTEMS DESIGN • Evaluating Design Alternatives – There are many design decisions that must be made. For example: • Should a document be hard-copy or sent by EDI? • Should the company use a large centralized mainframe or some form of distributed processing? • What form should data entry take, e.g., keyboard, optical character recognition, POS devices?

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CONCEPTUAL SYSTEMS DESIGN • Also, there are many ways to approach the systems development process: – – – –

Packaged software In-house development End-user development Outsourcing

• The company also chooses between: – Modifying or enhancing existing software – Replacing existing software – Reengineering its business processes © 2006 Prentice Hall Business Publishing

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CONCEPTUAL SYSTEMS DESIGN • The design team should identify a variety of design alternatives and evaluate each with respect to: – How well it meets organizational and system objectives – How well it meets user needs – Whether it is economically feasible – Its advantages and disadvantages

• The steering committee evaluates the alternatives. • Click here to view some of the design considerations and alternatives from Table 20-1 in your textbook.

Design Considerations

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • How should the communications channel be configured? • Point-to-point • •

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Multi-drop Line-sharing

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • How should the communications channel be configured? • What type of communications channel should be used? • Phone lines • • • •

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Coaxial cable Fiber optics Microwave Satellite

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • How should the communications channel be configured? • What type of communications channel should be used? • What type of communications network should be used? • Centralized • Decentralized • Distributed • Local area

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • How should the communications channel be configured? • What type of communications channel should be used? • What type of communications network should be used? • What type of storage media should be used • Tape for data? • • • • • © 2006 Prentice Hall Business Publishing

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • How should the communications channel be configured? • What type of communications channel should be used? • What type of communications network should be used? • What type of storage media should be used for data? • What type of data storage structure should be used? • •

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Files Database

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • How should the communications channel be configured? • What type of communications channel should be used? • What type of communications network should be used? • What type of storage media should be used for • Random data? • Sequential • What type of data storage structure should be • Indexed-sequential access used? • How should files be organized and accessed? © 2006 Prentice Hall Business Publishing

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • What media should be used to input data? • • • • • •

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Keying OCR MICR POS EDI Voice

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • What media should be used to input data? • What format will the input take? • • • •

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Source documents Turnaround documents Source data automation Screen

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • What media should be used to input data? • What format will the input take? • How will the system be operated? • In-house •

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Outsourcing

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • • • •

What media should be used to input data? What format will the input take? How will the system be operated? How frequently will outputs be produced? • • • • •

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Instantly Hourly Daily Weekly Monthly

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • • • • •

What media should be used to input data? What format will the input take? How will the system be operated? How frequently will outputs be produced? What media will be used for output? • • • • • •

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • • • • • •

What media should be used to input data? What format will the input take? How will the system be operated? How frequently will outputs be produced? What media will be used for output? How will output be scheduled? • •

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On demand At predetermined times

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • • • • • • •

What media should be used to input data? What format will the input take? How will the system be operated? How frequently will outputs be produced? What media will be used for output? How will output be scheduled? What format will the output take? • • • •

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Narrative Table Graph Electronic file or communication

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • • • • • • • •

What media should be used to input data? What format will the input take? How will the system be operated? How frequently will outputs be produced? What media will be used for output? How will output be scheduled? What format will the output take? What form will printed output take? • • •

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Pre-printed forms Turnaround documents System-generated forms

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • • • • • • • • •

What media should be used to input data? What format will the input take? How will the system be operated? How frequently will outputs be produced? What media will be used for output? How will output be scheduled? What format will the output take? What form will printed output take? What processing mode will be used? • • •

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • • • • • • • • • •

What media should be used to input data? What format will the input take? How will the system be operated? How frequently will outputs be produced? What media will be used for output? How will output be scheduled? • Personal computer What format will the output take? • Minicomputer What form will printed output take? • Mainframe What processing mode will be used? What type of processor will be utilized?

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • • • • • • • • • • •

What media should be used to input data? What format will the input take? How will the system be operated? How frequently will outputs be produced? What media will be used for output? How will output be scheduled? What format will the output take? What form will printed output take? What processing mode will be used? • Canned • Custom What type of processor will be utilized? How will software be acquired? • Modified

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • How will transactions be processed? • •

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By batch Online

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CONCEPTUAL DESIGN CONSIDERATIONS AND ALTERNATIVES • How will transactions be processed? • How frequently will updates occur?

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Instantly Hourly Daily Weekly Monthly

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Systems Analysis

Evaluate Design Alternatives

Prepare Design Specifications

Prepare Conceptual Systems Design report

Physical Design

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CONCEPTUAL SYSTEMS DESIGN • Prepare design specifications – Once a design has been selected, the project team develops the conceptual design specifications for the following elements: • Output •

Because output is what goes to the user and the system must be designed to meet user needs, the output specifications are prepared first.

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CONCEPTUAL SYSTEMS DESIGN • Prepare design specifications – Once a design has been selected, the project team develops the conceptual design specifications for the following elements: • Output • Data storage •

How will data be stored to produce the desired outputs?

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CONCEPTUAL SYSTEMS DESIGN • Prepare design specifications – Once a design has been selected, the project team develops the conceptual design specifications for the following elements: • Output • Data storage • Input •

What types of data must be entered to produce the desired outputs?

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CONCEPTUAL SYSTEMS DESIGN • Prepare design specifications – Once a design has been selected, the project team develops the conceptual design specifications for the following elements: • Output • Data storage • How will data be processed and in what sequence • Inputto produce the desired outputs? • Processing procedures and operations © 2006 Prentice Hall Business Publishing

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Systems Analysis

Evaluate Design Alternatives

Prepare Design Specifications

Prepare Conceptual Systems Design report

Physical Design

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CONCEPTUAL SYSTEMS DESIGN • Prepare the Conceptual Systems Design Report – A conceptual systems design report is prepared at the end of the conceptual design phase to: • Guide physical system design activities. • Communicate how management and user information needs will be met. • Help the steering committee assess system feasibility. © 2006 Prentice Hall Business Publishing

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CONCEPTUAL SYSTEMS DESIGN • The main component is a description of one or more recommended system designs. This description contains: – The contents of each output, database, and input. – Processing flows and the relationships among programs, files, inputs, and outputs. – Hardware, software, and resource requirements. – Audit, control, and security processes and procedures. – A discussion of assumptions or unresolved problems that might affect the final design. © 2006 Prentice Hall Business Publishing

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INTRODUCTION • The crucial phases of the SDLC include: – Systems analysis to define the new systems requirements (discussed in Chapter 18). – The phases discussed in this chapter, which include: • • • •

Conceptual systems design Physical systems design Systems implementation and conversion Operation and maintenance

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PHYSICAL SYSTEMS DESIGN • During the physical systems design phase, the company determines how the conceptual AIS design is to be implemented. – The broad, user-oriented requirements of conceptual design are translated into detailed specifications used to code and test computer programs. – Phases include: • • • • • •

Designing output Creating files and databases Designing input Writing computer programs Developing procedures Building in controls

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Systems Analysis

Physical Systems Design

Output Design

Conceptual Systems Design

File & DB Design

Input Design

Program Design

Procedures Design

Controls Design

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Systems Analysis

Conceptual Systems Design

Output Design

File & DB Design

Input Design

Program Design

Procedures Design

Controls Design

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PHYSICAL SYSTEMS DESIGN • Output Design – The objective of output design is to determine the nature, format, content, and timing of printed reports, documents, and screen displays. • Requires cooperation between users and designers.

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PHYSICAL SYSTEMS DESIGN • Important design considerations include: – Use of the output • • •

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Who will use it and why? When is it needed? What decisions will it facilitate?

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PHYSICAL SYSTEMS DESIGN • Important design considerations include: – Use of the output – Output medium

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• • • • • •

Paper Screen Voice response Diskette Microfilm Other

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PHYSICAL SYSTEMS DESIGN • Important design considerations include: – Use of the output – Output medium – Output format • •

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Should select the format that clearly conveys the most information. Could be: – Table – Narrative – Graphic

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PHYSICAL SYSTEMS DESIGN • Important design considerations include: – Use of the output – Output medium – Output format – Pre-printed • Should paper output be on preprinted form and/or turnaround document?

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PHYSICAL SYSTEMS DESIGN • Important design considerations include: – Use of the output – Output medium – Output format – Pre-printed – Location • Where is the output to be sent?

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PHYSICAL SYSTEMS DESIGN • Important design considerations include: – Use of the output – Output medium – Output format – Pre-printed – Location – Access • Who should be able to access hard-copy and screen output?

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PHYSICAL SYSTEMS DESIGN • Important design considerations include: – Use of the output – Output medium – Output format – Pre-printed – Location • Lengthy output should be preceded by an executive summary and a table of contents. – Access • Headings and legends organize data and – Detail highlight important items. •

Detailed info goes in an appendix.

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PHYSICAL SYSTEMS DESIGN • Important design considerations include: – Use of the output – Output medium – Output format – Pre-printed – Location – Access – Detail • How often should the output be produced? – Timeliness © 2006 Prentice Hall Business Publishing

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PHYSICAL SYSTEMS DESIGN • Outputs usually fit into one of the following four categories: – Scheduled reports • • •

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Have pre-specified content and format. Are prepared on a regular basis. Examples: – Weekly sales analysis – Monthly financial statements

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PHYSICAL SYSTEMS DESIGN • Outputs usually fit into one of the following four categories: – Scheduled reports – Special-purpose analysis reports • No pre-specified content and format. • Typically prepared in response to a management request. • Example: – Analysis of impact of a government mandate on profitability

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PHYSICAL SYSTEMS DESIGN • Outputs usually fit into one of the following four categories: – Scheduled reports – Special-purpose analysis reports – Triggered exception reports • Have pre-specified content and format. • Prepared only in response to abnormal conditions, i.e., the “trigger.” • Example: – Cost overruns © 2006 Prentice Hall Business Publishing

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PHYSICAL SYSTEMS DESIGN • Outputs usually fit into one of the following four categories: – Scheduled reports – Special-purpose analysis reports – Triggered exception reports – Demand reports • •

Have pre-specified content and format. Prepared only on request.

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PHYSICAL SYSTEMS DESIGN • AIS developers prepare sample outputs and users evaluate them to ensure they are complete, relevant, and useful. – Modifications are made as needed to ensure acceptability. – Many organizations require users to sign off on these documents before proceeding through the SDLC.

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Systems Analysis

Conceptual Systems Design

Output Design

File & DB Design

Input Design

Program Design

Procedures Design

Controls Design

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PHYSICAL SYSTEMS DESIGN • File and Database Design – Various company segments need to store data in compatible formats so that data can be shared across units. – Important file and database design considerations include: • Hard drive • Storage medium

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• • • • •

Disk Diskette CD Tape Paper

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PHYSICAL SYSTEMS DESIGN • File and Database Design – Various company segments need to store data in compatible formats so that data can be shared across units. – Important file and database design considerations include: • Storage medium • Processing mode

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• • •

Manual Batch Real time

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PHYSICAL SYSTEMS DESIGN • File and Database Design – Various company segments need to store data in compatible formats so that data can be shared across units. – Important file and database design considerations include: • Storage medium • Processing mode • Maintenance • What procedures are needed to effectively maintain the data?

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PHYSICAL SYSTEMS DESIGN • File and Database Design – Various company segments need to store data in compatible formats so that data can be shared across units. – Important file and database design considerations include: • • • •

Storage medium Processing mode Maintenance Size • How many records and how big are they? • How fast are they expected to grow?

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PHYSICAL SYSTEMS DESIGN • File and Database Design – Various company segments need to store data in compatible formats so that data can be shared across units. – Important file and database design considerations include: • • • • •

Storage medium • What portion of records are added or Processing mode deleted each year? Maintenance • What portion needs to be updated? Size Activity level

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Systems Analysis

Conceptual Systems Design

Output Design

File & DB Design

Input Design

Program Design

Procedures Design

Controls Design

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PHYSICAL SYSTEMS DESIGN • Input Design – Systems designers must identify the different types of data input and optimal input methods. – There are two principal types of data input: • Forms • Computer screens © 2006 Prentice Hall Business Publishing

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PHYSICAL SYSTEMS DESIGN • Considerations in input design include: – Input medium

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• • • • • •

Keyboard OCR MICR POS terminal EDI Voice input

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PHYSICAL SYSTEMS DESIGN • Considerations in input design include: – Input medium – Input source

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•

Where do data originate? – Computer – Customer – Remote location

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PHYSICAL SYSTEMS DESIGN • Considerations in input design include: – Input medium – Input source – Input format • What format captures the data with the least effort or cost? – Source or turnaround document – Screen – Source data automation

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PHYSICAL SYSTEMS DESIGN • Considerations in input design include: – – – –

Input medium Input source Input format Input type • What is the nature of the data?

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PHYSICAL SYSTEMS DESIGN • Considerations in input design include: – – – – –

Input medium Input source Input format Input type Volume • How much data are to be entered?

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PHYSICAL SYSTEMS DESIGN • Considerations in input design include: – – – – – –

Input medium Input source Input format Input type Volume Personnel • •

What functions and expertise do the data entry operators have? Is additional training necessary?

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PHYSICAL SYSTEMS DESIGN • Considerations in input design include: – – – – – – –

Input medium Input source Input format Input type Volume Personnel • How often is data to be entered? Frequency

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PHYSICAL SYSTEMS DESIGN • Considerations in input design include: – – – – – – – –

Input medium Input source Input format Input type Volume Personnel Frequency  How can costs be minimized without adversely affecting efficiency and Cost accuracy?

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PHYSICAL SYSTEMS DESIGN • Considerations in input design include: – – – – – – – – –

Input medium Input source Input format Input type Volume Personnel Frequency • What errors are possible? • How can they be detected and corrected? Cost Error detection and correction

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• Preprint as much data as possible. PHYSICAL SYSTEMS DESIGN

• Use appropriate weight and grade of paper. • Use bold type, double-thick lines, and shading to highlight different parts of the form. • Use a standard size and one that is consistent with Although inputforisfiling, evolving toward source data requirements binding, or mailing. • If mailed to external parties, position address for automation, forms design is still the important. placement in a window envelope. Following are important principles for • Have copies of the form printed in different colors to designing new forms and evaluating existing facilitate accurate distribution. • Include clear instructions for completing the form. ones:

• Forms Design – –

• General considerations

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PHYSICAL SYSTEMS DESIGN • Forms Design – Although input is evolving toward source data automation,• forms design is still important. Place the form name at the top in bold type. the forms pre-numbered • Have – Following are important principlesconsecutively. for • If distributed to external parties, have company designing new forms and pre-printed evaluating name and address on theexisting form. ones: • General considerations • Introductory section of form

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PHYSICAL SYSTEMS DESIGN • Forms Design – –

• Group together logically related information Although input(e.g., is evolving toward source datathe info about the customer, info about product). automation, forms design is still important. • Provide sufficient room to record each item. Following are important principles for • Order the data items consistent with the designing newsequence forms in and evaluating existing which the data is likely to be gathered. ones: • Use codes and check-offs in places where • General considerations standardized explanations are likely.

• Introductory section of form • Main body of form

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PHYSICAL SYSTEMS DESIGN • Forms Design – Although input is evolving toward source data automation, forms design is still important. • Provide space for: – Following are important principles for – final disposition of the form. designing new Recording forms and evaluating existing – Approval signatures. ones: – Dates of approval and final disposition. • • • •

General considerations – A dollar or numeric total. Introductory sectionindicate of form the distribution of • Clearly each Main body of formform. Conclusion section of form

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PHYSICAL SYSTEMS DESIGN • Designing Computer Screens – It is more efficient to enter data directly into the computer than to record it on paper for subsequent entry. – Therefore, it’s important to design computer screens for input as well as output.

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PHYSICAL SYSTEMS DESIGN • Computer screens are most effective when the following principles are used: – Organize the screen for quick, accurate, and complete entry of the data. • Minimize input by retrieving as much as possible from the system. • Example: If the customer number is entered, retrieve his name/address data from the system.

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PHYSICAL SYSTEMS DESIGN • Computer screens are most effective when the following principles are used: – Organize the screen for quick, accurate, and complete entry of the data. – Enter data in the same order it appears on the document.

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PHYSICAL SYSTEMS DESIGN • Computer screens are most effective when the following principles are used: – Organize the screen for quick, accurate, and complete entry of the data. – Enter data in the same order it appears on the document. – Complete the screen from left to right and top to bottom, grouping logically related data together.

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PHYSICAL SYSTEMS DESIGN • Computer screens are most effective when the following principles are used: – Organize the screen for quick, accurate, and complete entry of the data. – Enter data in the same order it appears on the document. – Complete the screen from left to right and top to bottom, grouping logically related data together. – Design the screen so users can jump from one data entry location to another or use a single key to go directly to screen locations.

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PHYSICAL SYSTEMS DESIGN • Computer screens are most effective when the following principles are used: – Organize the screen for quick, accurate, and complete entry of the data. – Enter data in the same order it appears on the document. – Complete the screen from left to right and top to bottom, grouping logically related data together. – Design the screen so users can jump from one data entry location to another or use a single key to go directly to screen locations. – Make it easy to correct mistakes. • Use clear and explicit error messages that are consistent on all screens. • Provide a help feature for online assistance. © 2006 Prentice Hall Business Publishing

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PHYSICAL SYSTEMS DESIGN • Computer screens are most effective when the following principles are used: – Organize the screen for quick, accurate, and complete entry of the data. – Enter data in the same order it appears on the document. – Complete the screen from left to right and top to bottom, grouping logically related data together. – Design the screen so users can jump from one data entry location to another or use a single key to go directly to screen locations. • Limit the number of menu options on a single screen. – Make it easy to correct mistakes. – Avoid clutter by restricting the amount of data on one screen. © 2006 Prentice Hall Business Publishing

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Systems Analysis

Conceptual Systems Design

Output Design

File & DB Design

Input Design

Program Design

Procedures Design

Controls Design

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PHYSICAL SYSTEMS DESIGN • Program Design – Program development is one of the most timeconsuming activities in the SDLC. – A structured programming process should be followed: • With structured programming, programs should be subdivided into small, well-defined modules to reduce complexity and enhance reliability and modifiability. • Modules should interact with a control module rather than with each other. • To facilitate testing and modification, each module should have only one entry and exit point.

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PHYSICAL SYSTEMS DESIGN • To improve software quality, organizations should develop programming standards (rules for writing programs). – Contributes to consistency among programs. – Makes them easier to read and maintain.

• Consider doing structured program walkthroughs to find incorrect logic, errors, omissions, or other problems.

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PHYSICAL SYSTEMS DESIGN • Program preparation time may range from a few days to a few years, depending on complexity. • Though accountants need not be programmers, they should understand how software is created. • The following slides discuss the eight steps for developing software and where these steps take place in the SDLC.

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PHYSICAL SYSTEMS DESIGN Systems Analysis

• STEP ONE: Determine user needs.

Conceptual Design

– Occurs during the systems analysis stage of the SDLC.

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PHYSICAL SYSTEMS DESIGN Systems Analysis

• STEP TWO: Develop and document a plan.

Conceptual Design

– Occurs during the conceptual design phase and the beginning of physical design.

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PHYSICAL SYSTEMS DESIGN Systems Analysis

• STEP THREE: Write the program code.

Conceptual Design

Physical Design Implementation And Conversion

– Design in increasing levels of detail, known as hierarchical program design. – Begun during systems design and completed during systems implementation.

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PHYSICAL SYSTEMS DESIGN Systems Analysis

Conceptual Design

Physical Design Implementation And Conversion Operation And Maintenance

• STEP FOUR: Test the program code. – Debugging is discovering and eliminating program errors. – Desk checking happens after a program is coded and involves a visual and mental review to discover programming errors. – Programs are tested for logic errors using test data that simulates both valid transactions and all possible error conditions.

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PHYSICAL SYSTEMS DESIGN Systems Analysis

Conceptual Design

Physical Design Implementation And Conversion

– Large programs are often tested in three stages: • Individual program modules. • The linkages between the module and the control module. • The interfaces between the program being tested and other application programs.

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PHYSICAL SYSTEMS DESIGN Systems Analysis

Conceptual Design

Physical Design

– Errors need to be found as soon as possible in the development process. – Errors discovered late cost 801000% more to fix than those found early.

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PHYSICAL SYSTEMS DESIGN Systems Analysis

Conceptual Design

Physical Design Implementation And Conversion Operation And Maintenance

• STEP FIVE: Document the program. – Documentation explains how programs work and helps correct and resolve errors. – Includes flowcharts, record layouts, E-R diagrams, REA data models, narrative descriptions of the system, etc., organized in a manual.

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PHYSICAL SYSTEMS DESIGN Systems Analysis

Conceptual Design

• STEP SIX: Train program users. – Often uses the program documentation.

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PHYSICAL SYSTEMS DESIGN Systems Analysis

Conceptual Design

• STEP SEVEN: Install the system. - All components are brought together, and the company begins to use the system.

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PHYSICAL SYSTEMS DESIGN Systems Analysis

• STEP EIGHT: Use and modify the system.

Conceptual Design

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– Program maintenance is a response to any factors that require program revision. – Includes requests for: • New or revised reports. • Changes in input, file content, or values such as tax rates. • Error detection and correction. • Conversion to new hardware. Accounting Information Systems, 10/e

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Systems Analysis

Conceptual Systems Design

Output Design

File & DB Design

Input Design

Program Design

Procedures Design

Controls Design

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PHYSICAL SYSTEMS DESIGN • Procedures Design – Individuals who interact with a newly-designed AIS need procedures to cover: • • • • • • • •

Input preparation Transaction processing Error detection and correction Controls Reconciliation of balances Database access Output preparation and distribution Computer operator instructions

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PHYSICAL SYSTEMS DESIGN • Procedures may take the form of: – System manuals – User instruction classes – Training materials – Online help screens

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PHYSICAL SYSTEMS DESIGN • The procedures may be written by: – Development teams; – Users; or – Teams representing both groups.

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Systems Analysis

Conceptual Systems Design

Output Design

File & DB Design

Input Design

Program Design

Procedures Design

Controls Design

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PHYSICAL SYSTEMS DESIGN • Controls Design – Improperly controlled input, processing, and database functions produce information of questionable value. – Controls must be built into an AIS to ensure its effectiveness, efficiency, and accuracy. These controls should: • Minimize errors • Detect and correct errors when they do occur

– Accountants play a vital role in this area. © 2006 Prentice Hall Business Publishing

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PHYSICAL SYSTEMS DESIGN • Important control concerns that must be addressed include: – Validity

•

Are all interactions valid?

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PHYSICAL SYSTEMS DESIGN • Important control concerns that must be addressed include: – Validity – Authorization •

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Are input, processing, storage, and output activities authorized by the appropriate managers?

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PHYSICAL SYSTEMS DESIGN • Important control concerns that must be addressed include: – Validity – Authorization – Accuracy • Is input verified to ensure accuracy? •

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What controls ensure that data is not lost when passing between processing activities?

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PHYSICAL SYSTEMS DESIGN • Important control concerns that must be addressed include: – – – –

Validity Authorization Accuracy Security •

Is the system protected against: – Unauthorized physical and logical access to prevent improper use, alteration, destruction, or disclosure of information and software? – Theft of system resources?

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PHYSICAL SYSTEMS DESIGN • Important control concerns that must be addressed include: – – – – –

Validity Authorization Accuracy Security Numerical control •

Are documents pre-numbered to prevent errors or intentional misuse and to detect when documents are missing or stolen?

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PHYSICAL SYSTEMS DESIGN • Important control concerns that must be addressed include: – – – – – –

Validity Authorization Accuracy Security Numerical control Availability • Is the system available as set forth in agreements? • Can users enter, update, and retrieve data during those times?

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PHYSICAL SYSTEMS DESIGN • Important control concerns that must be addressed include: – – – – – – –

Validity • Can the system be modified without affecting system Authorization availability, security, and integrity? Accuracy • Are only authorized, tested, and documented changes made to the system and data? Security • Are resources available to manage, schedule, document, Numerical control changes to management and and communicate authorized users? Availability Maintainability

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PHYSICAL SYSTEMS DESIGN • Important control concerns that must be addressed include: – – – – – – – –

Validity Authorization Accuracy Security • Is processing complete, accurate, timely, and Numerical control authorized? Availability• Is it free from unauthorized or inadvertent manipulations? Maintainability Integrity

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PHYSICAL SYSTEMS DESIGN • Important control concerns that must be addressed include: – – – – – – – – –

Validity Authorization Accuracy Security Numerical control Availability • Can data be traced from source to output and vice Maintainability versa? Integrity Audit trail

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PHYSICAL SYSTEMS DESIGN • Physical Systems Design Report – At the end of the physical design phase, a physical systems design report is prepared, summarizing what was accomplished. – This report serves as the basis for management’s decision whether to proceed to implementation.

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PHYSICAL SYSTEMS DESIGN • Physical Systems Design Report – At the end of the physical design phase, a physical systems design report is prepared, summarizing what was accomplished. – This report serves as the basis for management’s decision whether to proceed to implementation.

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INTRODUCTION • The crucial phases of the SDLC include: – Systems analysis to define the new systems requirements (discussed in Chapter 18). – The phases discussed in this chapter, which include: • • • •

Conceptual systems design Physical systems design Systems implementation and conversion Operation and maintenance

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SYSTEMS IMPLEMENTATION AND CONVERSION • SYSTEMS IMPLEMENTATION – Systems implementation is the process of installing hardware and software and getting the AIS up and running. – Phases include: • • • • • •

Developing a plan Preparing the site Installing and testing hardware and software Selecting and training personnel Completing documentation Testing the system

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Systems Analysis

Conceptual Systems Design

System Implementation And Conversion

Implementation Planning

Physical Systems Design Prepare site; Install & test hardware

Complete documentation

Select & Train Personnel

Test system

Conversion

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Systems Analysis

Conceptual Systems Design Physical Systems Design

Implementation Planning

Prepare site; Install & test hardware

Complete documentation

Select & Train Personnel

Test system

Conversion

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SYSTEMS IMPLEMENTATION AND CONVERSION • Implementation Planning – An implementation plan consists of: • • • •

Implementation tasks Expected completion dates Cost estimates Specification of the person(s) responsible for each task

– The plan specifies when the project should be complete and operational. – The implementation team should identify risk factors that decrease the likelihood of successful implementation, and the plan should contain a strategy for coping with each of the risks. © 2006 Prentice Hall Business Publishing

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SYSTEMS IMPLEMENTATION AND CONVERSION • AIS changes may require adjustments to the company’s organizational structure, including: – Creation of new departments. – Elimination or downsizing of existing departments. – Changes even in the data processing department.

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Systems Analysis

Conceptual Systems Design Physical Systems Design

Implementation Planning

Prepare site; Install & test hardware

Complete documentation

Select & Train Personnel

Test system

Conversion

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SYSTEMS IMPLEMENTATION AND CONVERSION • Site Preparation – A large computer may require changes such as: • New electrical outlets • Data communications facilities • Raised floors • Humidity controls • Special lighting • Air-conditioning • Security measures, such as: – Fire protection – Emergency power supply • Space for equipment, storage, and offices © 2006 Prentice Hall Business Publishing

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SYSTEMS IMPLEMENTATION AND CONVERSION • Site preparation is a lengthy process and should begin well ahead of the installation date.

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Systems Analysis

Conceptual Systems Design Physical Systems Design

Implementation Planning

Prepare site; Install & test hardware

Complete documentation

Select & Train Personnel

Test system

Conversion

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SYSTEMS IMPLEMENTATION AND CONVERSION • Select and Train Personnel – Employees can be hired from outside or transferred internally. • Hiring within is usually more effective and less costly, because the employees already understand the business. • Transferring displaced employees can enhance loyalty and morale.

– Companies take training shortcuts because: • Effective training is time-consuming and expensive. • Those who understand the system are maintaining and upgrading it. © 2006 Prentice Hall Business Publishing

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SYSTEMS IMPLEMENTATION AND CONVERSION • When training is insufficient, the company will not achieve the expected return on investment. • The hidden cost is that users will turn to their coworkers who have mastered the system for help. Results in: – Less productive coworkers – Increased costs

• Effective training includes: – Hardware and software skills – Orientation to new policies and operations

• The training should be scheduled just before systems testing and conversion.

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SYSTEMS IMPLEMENTATION AND CONVERSION • Types of training include: – Technical training from vendors – Self-study manuals – Computer-aided instruction – Videotape presentations – Role-playing – Case studies – Experimenting with the AIS under the guidance of experienced users

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Systems Analysis

Conceptual Systems Design Physical Systems Design

Implementation Planning

Prepare site; Install & test hardware

Complete documentation

Select & Train Personnel

Test system

Conversion

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SYSTEMS IMPLEMENTATION AND CONVERSION • Three types of documentation must be prepared for new systems: – Development documentation • Describes the AIS and includes: – – – – –

A system description Copies of output, input, file, and database layouts Program flowcharts Test results User acceptance forms

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SYSTEMS IMPLEMENTATION AND CONVERSION • Three types of documentation must be prepared for new systems: – Development documentation – Operations documentation • Includes: – Operating schedules – Files and databases accessed – Equipment, security, and file retention requirements

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SYSTEMS IMPLEMENTATION AND CONVERSION • Three types of documentation must be prepared for new systems: – Development documentation – Operations documentation – User documentation • Teaches users how to operate the AIS. • Includes a procedures manual and training materials.

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Systems Analysis

Conceptual Systems Design Physical Systems Design

Implementation Planning

Prepare site; Install & test hardware

Complete documentation

Select & Train Personnel

Test system

Conversion

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SYSTEMS IMPLEMENTATION AND CONVERSION • Test the System – Inadequate system testing has contributed to the failure of systems. – All of the following should be given a trial run in realistic circumstances. • • • • •

Documents and reports User input Operating and control procedures Processing procedures Computer programs

– Should also test: • Capacity limits • Backup and recovery procedures © 2006 Prentice Hall Business Publishing

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SYSTEMS IMPLEMENTATION AND CONVERSION • Three common forms of testing include: – Walk-throughs • Step-by-step reviews of procedures or program logic. – Attended by the development team and users early in system design. – Focus is on organization: • Input • Files • Outputs • Data flows – Subsequent walk-throughs are attended by programmers. • Address logical and structural aspects of program code. © 2006 Prentice Hall Business Publishing

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SYSTEMS IMPLEMENTATION AND CONVERSION • Three common forms of testing include: – Walk-throughs – Processing test transactions • • •

Determines whether the program operates as designed. Requires both valid and erroneous data. The correct response for each test should be specified in advance.

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SYSTEMS IMPLEMENTATION AND CONVERSION • Three common forms of testing include: – Walk-throughs – Processing test transactions – Acceptance tests • Uses copies of real transactions and files rather than hypothetical ones. – Users develop acceptance criteria. – Then make final decision whether to accept

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SYSTEMS IMPLEMENTATION AND CONVERSION • Three common forms of testing include: – Walk-throughs – Processing test transactions – Acceptance tests

• Even software purchased from an outside vendor must be tested thoroughly before installation.

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Systems Analysis

Conceptual Systems Design Physical Systems Design

Implementation Planning

Prepare site; Install & test hardware

Complete documentation

Select & Train Personnel

Test system

Conversion

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SYSTEMS IMPLEMENTATION AND CONVERSION • Systems Conversion – Conversion is the process of changing from the old AIS to the new. – Many elements must be converted, including: • • • •

Hardware Software Data files Procedures

– The process is complete when the new AIS has become a routine, ongoing part of the system.

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SYSTEMS IMPLEMENTATION AND CONVERSION • Conversion Approaches – Four conversion approaches are used to change from an old to a new system: • • • •

Direct conversion Parallel conversion Phase-in conversion Pilot conversion

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SYSTEMS IMPLEMENTATION AND CONVERSION • Conversion Approaches – Four conversion approaches are used to change from an old to a new system: • • • •

Direct conversion Parallel conversion Phase-in conversion Pilot conversion

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SYSTEMS IMPLEMENTATION AND CONVERSION • Direct conversion – Immediately terminates the old AIS when the new one is introduced. – Appropriate when: • The old AIS has no value; or • The new AIS is so different that comparisons between the two are meaningless.

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SYSTEMS IMPLEMENTATION AND CONVERSION • Main advantage to direct conversion: – It’s inexpensive

• Main disadvantage: – It provides no backup AIS.

• There is a high risk of failure unless the new system has been very carefully developed and tested.

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SYSTEMS IMPLEMENTATION AND CONVERSION • Conversion Approaches – Four conversion approaches are used to change from an old to a new system: • • • •

Direct conversion Parallel conversion Phase-in conversion Pilot conversion

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SYSTEMS IMPLEMENTATION AND CONVERSION • Parallel conversion – Operates the old and new systems simultaneously for a period of time. – You can process transactions with both systems, compare output, reconcile differences, and make corrections to the new AIS.

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SYSTEMS IMPLEMENTATION AND CONVERSION • Main advantage to parallel conversion: – It protects the company from errors.

• Main disadvantage: – It is costly and stressful for employees to process all transactions twice.

• Because companies often experience problems during conversion, parallel processing has gained widespread popularity.

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SYSTEMS IMPLEMENTATION AND CONVERSION • Conversion Approaches – Four conversion approaches are used to change from an old to a new system: • • • •

Direct conversion Parallel conversion Phase-in conversion Pilot conversion

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SYSTEMS IMPLEMENTATION AND CONVERSION • Phase-in conversion – Gradually replaces elements of the old AIS with the new one. – The new system is often phased in a module at a time. – Main Advantage: • Data processing resources can be acquired over time.

– Disadvantages: • Costs of creating temporary interfaces between old and new AIS. • Time required to make the complete conversion.

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SYSTEMS IMPLEMENTATION AND CONVERSION • Conversion Approaches – Four conversion approaches are used to change from an old to a new system: • • • •

Direct conversion Parallel conversion Phase-in conversion Pilot conversion

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SYSTEMS IMPLEMENTATION AND CONVERSION • Pilot conversion – Implements a system in just one part of the organization, e.g., a branch office or a single store. – When problems with the system are resolved, the new system could be implemented at the remaining locations. – Advantages: • Localizes conversion problems and allows training in a live environment.

– Disadvantages: • Long conversion time. • Need for interfaces between old and new systems.

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SYSTEMS IMPLEMENTATION AND CONVERSION • Data Conversion – Data conversion can be time-consuming, tedious, and expense. – The difficulty and magnitude is easy to underestimate. – Data files may need to be modified in three ways: • Files may be moved to a different storage medium (e.g., tape to disk). • Data content may be changed (e.g., fields added or deleted). • A file or database format may be changed. © 2006 Prentice Hall Business Publishing

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SYSTEMS IMPLEMENTATION AND CONVERSION • Steps in the data conversion process: – Decide which data files need to be converted. – Check files for completeness and data inaccuracies, and remove any inconsistencies. – Do the actual data conversion. – Validate the new files to ensure data were not lost during conversion. – If the file conversion is lengthy, update the new files with transactions that occurred during data conversion. – After conversion and testing, monitor the system to make sure it runs smoothly and accurately. – Document the conversion activities. © 2006 Prentice Hall Business Publishing

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Systems Analysis

Conceptual Systems Design

Physical Design

Implementation And Conversion Operation And Maintenance © 2006 Prentice Hall Business Publishing

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OPERATIONS AND MAINTENANCE • The last step in the SDLC is to operate and maintain the new system. • A post-implementation review should be conducted to ensure the new AIS meets its planned objectives.

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OPERATIONS AND MAINTENANCE • Factors and questions include: – Goals and objectives •

Does the system help the organization meet its goals, objectives, and overall mission?

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OPERATIONS AND MAINTENANCE • Factors and questions include: – Goals and objectives – Satisfaction • •

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Are users satisfied? Do they want changes or improvements?

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OPERATIONS AND MAINTENANCE • Factors and questions include: – Goals and objectives – Satisfaction – Benefits • Were the expected benefits achieved?

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OPERATIONS AND MAINTENANCE • Factors and questions include: – Goals and objectives – Satisfaction – Benefits – Costs • Are actual costs in line with expected costs?

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OPERATIONS AND MAINTENANCE • Factors and questions include: – Goals and objectives – Satisfaction – Benefits – Costs – Reliability • Has the system failed, and if so, why?

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OPERATIONS AND MAINTENANCE • Factors and questions include: – Goals and objectives – Satisfaction – Benefits – Costs – Reliability – Accuracy • Does the system produce accurate and complete data? © 2006 Prentice Hall Business Publishing

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OPERATIONS AND MAINTENANCE • Factors and questions include: – Goals and objectives – Satisfaction – Benefits – Costs – Reliability – Accuracy • Does the system produce timely information? – Timeliness © 2006 Prentice Hall Business Publishing

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OPERATIONS AND MAINTENANCE • Factors and questions include: – Compatibility • Are hardware, software, data, and procedures compatible with existing systems?

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OPERATIONS AND MAINTENANCE • Factors and questions include: – Compatibility – Controls and security • Are there safeguards against unintentional errors, fraud, and intrusion?

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OPERATIONS AND MAINTENANCE • Factors and questions include: – Compatibility – Controls and security – Errors • Are there adequate error-handling procedures?

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OPERATIONS AND MAINTENANCE • Factors and questions include: – Compatibility – Controls and security – Errors – Training •

Are systems personnel and users adequately trained?

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OPERATIONS AND MAINTENANCE • Factors and questions include: – Compatibility – Controls and security – Errors – Training – Communications •

Is the communications system adequate?

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OPERATIONS AND MAINTENANCE • Factors and questions include: – Compatibility – Controls and security – Errors • Are structural changes that resulted from the system – Training beneficial or harmful? • If harmful, how can they be resolved? – Communications – Organization changes © 2006 Prentice Hall Business Publishing

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OPERATIONS AND MAINTENANCE • Factors and questions include: – Compatibility – Controls and security – Errors – Training – Communications • Is documentation complete and accurate? – Organization changes – Documentation © 2006 Prentice Hall Business Publishing

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OPERATIONS AND MAINTENANCE • Any problems discovered during the review should be brought to management’s attention, and adjustments should be made. • When the review is complete, a postimplementation review report is prepared. • User acceptance of that report is the final activity in systems development.

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OPERATIONS AND MAINTENANCE • Control of the AIS is then passed to the data processing department. • But the work is not done. – About 30% of the work takes place during development. – The remaining 70% is spent in maintaining the system—particularly with respect to software modifications and updates.

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SUMMARY AND CONCLUSIONS • You’ve learned in more depth about the activities that take place in the conceptual design phase of the systems development life cycle (SDLC). • You’ve also learned about activities that take place in the physical systems design phase. • You’ve explored what happens during the systems implementation and conversion process. • Finally, you’ve learned about the activities in the last phase of the systems development life cycle— the systems operation and maintenance process.

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