Dac3193 - Accounting Information System II

7/30/2019 Dac3193 - Accounting Information System II

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DAC3193 -

ACCOUNTING

INFORMATION SYSTEM IICHAPTER 5: SYSTEM DESIGN


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INTRODUCTION

Design phase focus on the development of newsystem with the requirements of user.

The Design stage describes how the proposed

solution is to be developed. The solution designis specific to the systems technical environmentand the tools to be used in constructing thesystem.

The results of this stage will be inputs to the

Execute and Implement stages.Design and development process of newproducts


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OBJECTIVE DESIGN PHASEThe primary objective of the design phase is tocreate a des ign that satisfies the agreedapplication requirements.

In the design phase the SDLC process continues

to move from the "what" questions of theanalysis phase to the " how" ques tio ns.

The requirements prototype that was developedearlier during the analysis phase is graduallyimproved and extended to include all the

specified functions of the application.


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PURPOSE OF DESIGN PHASEDetailed requirements are transformed intodetailed specifications for the system to guidethe work of the Execute stage.

For complex projects there may be an iterativerelationship between the Design and Executestages.

Infrastructure architecture decisions are made toaddress how the system will meet the defined

functional, physical, interface, informationprotection and data requirements.


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PURPOSE OF DESIGN PHASEIt is the most crucial phase in the development of asystem. The logical system design arrived at as a result ofsystem analysis and is converted into physical systemdesign.

In the design phase the SDLC process continues to movefrom the what questions of the analysis phase to the how .

The logical design produced during the analysis is turnedinto a physical design - a detailed description of what isneeded to solve original problem.


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PURPOSE OF DESIGN PHASEInput, output, databases, forms, codification schemes andprocessing specifications are drawn up in detail.

In the design stage, the programming language and thehardware and software platform in which the new system

will run are also decided.

Data structure, control process, equipment source,workload and limitation of the system, Interface,documentation, training, procedures of using the system,taking backups and staffing requirement are decided at

this stage.


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DESIGN REQUIREMENTS

RESEARCH:

The design process begins with research. Almost allprojects require the builders or makers to ask a series ofquestions--of themselves or clients--about the purpose of

the project and the needs to fill.For example, architectural designers or home builders askclients questions concerning the size of interior spaces,the types of people for whom the building is being builtand any custom-tailored requests.

Questions of style come into play during this phase aswell. Other questions during the research phase concern aproject's budget and time line for completion. Themaker or client may examine similar projects that havebeen successfully completed.


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CONCEPTUALIZATIONThe conceptualization phase of the design processinvolves outlining the project. During this phase,designers may have a list of features or requirements thatthe project will include. They conduct brainstorming

sessions to generate additional ideas.Some designers draw a rough paper-and-pencil orcomputer-generated sketch of what the result will look like,encompassing all project requirements and features.

When conceptualizing, designers often modify the rough

sketch or outline to satisfy a change in needs orpreferences from clients.


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DESIGNDEVELOPMENT

The design development phase involves a closer, detailedlook at the project. This phase involves creating detailedplans, drawings and drafts and devoting attention to each

feature or specification.For example, architectural designers and builders usecomputer-aided design programs to model a new buildingto scale, ensuring the design, measurement and placementof doors, stairways and hallways.

Art project designers, such as graphic and logo designartists, construct several drafts or proofs.

Design development allows additional feedback from clientsand last-minute changes to be made and approved. Duringthis phase, designers or builders often assess final costsfor the project.


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DEVELOPMENT ANDCOMPLETION

The development stage involves creating and building theproject itself. The designer gathers supplies to completethe project.

Large designs and projects require continual involvement

from all team members, including project managers,leaders and engineers, to ensure work goes according toplan.

An architectural project may require on-site visits from aproperty owner to ensure satisfaction. Any last-minute

changes or added requirements during this stage mightresult in additional expenses.

When development is completed, the designer evaluatesthe project and shows the result to clients.


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CODING

The system design needs to be implemented to make it aworkable system. his demands the coding of design intocomputer language, i.e., programming language. This is alsocalled the programming phase in which the programmerconverts the program specifications into computer instructions,

which we refer to as programs.It is an important stage where the defined procedures aretransformed into control specifications by the help of a computerlanguage. The programs coordinate the data movements andcontrol the entire process in a system.

A well written code reduces the testing and maintenance effort. It

is generally felt that the programs must be modular in nature.This helps in fast development, maintenance and futurechanges, if required. Programming tools like compilers,interpreters and language like c, c++, and java etc., are used forcoding .with respect to the type of application. The rightprogramming language should be chosen


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SYSTEM DESIGN

SPECIFICATIONThe System Design Specification (SDS) is a complete document that contains all of the information needed to develop the system.

The major sections of the SDS should be:

1. Introduction

2. Project Scope

3. System Design

4. Component and Process Design

5. Data Design

6. User Displays and Output Reports

7. System Files

8. Prototype Description

9. Prototype Test Procedures

10. Prototype Analysis

11. System Development and Project Management Schedules

12. Special Notes

13. Project Extensions

14. Appendices


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ACCOUNTANT ROLES IN

DESIGN PHASE

Accountants must understand the entire systemsdevelopment process, because they are involved inseveral 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.


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ACCOUNTANT ROLES IN

DESIGN PHASE

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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CONCEPTUAL

SYSTEMS DESIGN

In the conc eptual systems designphase, a general framework iscreated for implementing user requirements and solving theproblems identified in the analysis phase.

The three main steps are:

Evaluate design alternatives. Prepare design specifications.

Prepare the conceptual systems design report.


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Systems

Analysis

Prepare

Design

Specifications

Physical

Design

Implementation

and

Conversion

Operation

and

Maintenance

Prepare

Conceptual Systems

Design Report

Evaluate

Design

Alternatives

Conceptual

Systems

Design


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Systems

Analysis

Prepare

Design

Specifications

Physical

Design

Implementation

and

Conversion

Operation

and

Maintenance

Prepare

Conceptual Systems

Design Report

Evaluate

Design

Alternatives


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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


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CONCEPTUAL

SYSTEMS DESIGN

The design team should identify a variety of designalternatives 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 considerationsand alternatives from Table 20-1 in your textbook.

Design Considerations


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Systems

Analysis

Prepare

Design

Specifications

Physical

Design

Implementation

and

Conversion

Operation

and

Maintenance

Prepare

Conceptual Systems

Design Report

Evaluate

Design

Alternatives


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CONCEPTUAL

SYSTEMS DESIGN

Prepare design specifications

Once a design has been selected, the project

team develops the conceptual design

speci f icat ionsfor the following elements:

Output

Because output is what goes to the user andthe system must be designed to meet userneeds, the output specifications are preparedfirst.


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CONCEPTUAL

SYSTEMS DESIGN





Output

Data storage

How will data be stored to produce thedesired outputs?


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CONCEPTUAL

SYSTEMS DESIGN





Output

Data storage

Input

What types of data must be entered toproduce the desired outputs?


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CONCEPTUAL

SYSTEMS DESIGN


Once a design has been selected, the projectteam develops the conceptual design

speci f icat ionsfor the following elements: Output

Data storage

Input

Processing procedures and operations How will data be processed and in whatsequence to produce the desired outputs?


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Systems

Analysis

Prepare

Design

Specifications

Physical

Design

Implementation

and

Conversion

Operation

and

Maintenance

Prepare

Conceptual Systems

Design Report

Evaluate

Design

Alternatives


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CONCEPTUAL

SYSTEMS DESIGN

Prepare the conceptual systems design report

A conc eptual systems design repor tis prepared at the end of the

conceptual design phase to:

Guide physical system design activities.

Communicate how management and user information needs will bemet.

Help the steering committee assess system feasibility.


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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 mightaffect the final design.


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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, thecompany determines how the conceptual AIS designis to be implemented.

The broad, user-oriented requirements of conceptual design aretranslated into detailed specifications used to code and testcomputer 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

Conceptual

Systems

Design

Output

Design

Implementation

and

Conversion

Operation

and

Maintenance

File and DB

Design

Input

Design

Program

Design

Proce-dures

Design

Controls

Design

Physical

Systems

Design


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Systems

Analysis

Conceptual

Systems

Design

Output

Design

Implementation

and

Conversion

Operation

and

Maintenance

File and DB

Design

Input

Design

Program

Design

Proce-dures

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

Who will use it and why?

When is it needed? What decisions will it

facilitate?


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PHYSICAL SYSTEMS

DESIGN


Use of the output

Output medium Paper

Screen

Voice

response Diskette

Microfilm

Other


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PHYSICAL SYSTEMS

DESIGN


Use of the output

Output medium

Output format

Should select the format thatclearly conveys the mostinformation.

Could be:

Table

Narrative

Graphic


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PHYSICAL SYSTEMS

DESIGN


Use of the output

Output medium

Output format

Pre-printed

Should paper output beon preprinted formand/or turnaround

document?


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PHYSICAL SYSTEMS

DESIGN


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


Use of the output

Output medium

Output format

Pre-printed

Location

Access

Who should be able toaccess hard-copy andscreen output?


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PHYSICAL SYSTEMS

DESIGN


Use of the output

Output medium

Output format

Pre-printed

Location

Access

Detail Lengthy output should be preceded by

an executive summary and a table ofcontents.

Headings and legends organize dataand highlight important items.

Detailed info goes in an appendix.


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PHYSICAL SYSTEMS

DESIGN


Use of the output

Output medium

Output format

Pre-printed

Location

Access

Detail

Timeliness

How often should the output beproduced?


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PHYSICAL SYSTEMS

DESIGN

Outputs usually fit into one of the following four categories:

Scheduled reports

Have pre-specified content andformat.

Are prepared on a regular basis.

Examples:

Weekly sales analysis

Monthly financial statements


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PHYSICAL SYSTEMS

DESIGN


Scheduled reports

Special-purpose analysis reports

No pre-specified content andformat.

Typically prepared in response to a

management request.

Example:

Analysis of impact of a governmentmandate on profitability


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PHYSICAL SYSTEMS

DESIGN


Scheduled reports


Triggered exception reports

Have pre-specified content and

format. Prepared only in response to abnormal

conditions, i.e., the trigger.

Example:

Cost overruns


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PHYSICAL SYSTEMS

DESIGN


Scheduled reports


Triggered exception reports

Demand reports

Have pre-specified content andformat.

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

OutputDesign

Implementation

and

Conversion

Operation

and

Maintenance

File and DBDesign

InputDesign

ProgramDesign

Proce-dures

Design

ControlsDesign


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Systems

Analysis

Conceptual

Systems

Design

OutputDesign

Implementation

and

Conversion

Operation

and

Maintenance

File and DBDesign

InputDesign

ProgramDesign

Proce-dures

Design

ControlsDesign


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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


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PHYSICAL SYSTEMS

DESIGN

Considerations in input design include:

Input medium Keyboard

OCR

MICR

POS terminal

EDI

Voice input


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PHYSICAL SYSTEMS

DESIGN


Input medium

Input source

Where do dataoriginate?

Computer

Customer Remote location


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PHYSICAL SYSTEMS

DESIGN


Input medium

Input source

Input format What format captures the datawith the least effort or cost?

Source or turnaround document

Screen

Source data automation


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PHYSICAL SYSTEMS

DESIGN


Input medium

Input source

Input format

Input type What is the nature of the

data?


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PHYSICAL SYSTEMS

DESIGN


Input medium

Input source

Input format

Input type

Volume How much data are to be

entered?


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PHYSICAL SYSTEMS

DESIGN


Input medium

Input source

Input format

Input type

Volume

Personnel

What functions and expertise do thedata entry operators have?

Is additional training necessary?


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PHYSICAL SYSTEMS

DESIGN


Input medium

Input source

Input format

Input type

Volume

Personnel

Frequency

How often is data to beentered?

S C S S S


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PHYSICAL SYSTEMS

DESIGN


Input medium

Input source

Input format

Input type

Volume

Personnel

Frequency

Cost How can costs be minimizedwithout adversely affectingefficiency and accuracy?

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN


Input medium

Input source

Input format

Input type

Volume

Personnel

Frequency

Cost

Error detection and correction

What errors are possible? How can they be detected and

corrected?

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

Forms design

Although input is evolving toward source data automation, forms

design is still important.

Following are important principles for designing new forms and

evaluating existing ones: General considerations

Preprint as much data as possible.

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 withrequirements for filing, binding, or mailing.

If mailed to external parties, position the addressfor placement in a window envelope.

Have copies of the form printed in different colorsto facilitate accurate distribution.

Include clear instructions for completing the form.

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

Forms design





Introductory section of form

Place the form name at the top in bold

type.

Have the forms pre-numberedconsecutively.

If distributed to external parties, havecompany name and address pre-

printed on the form.

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

Forms design






Main body of form

Group together logically relatedinformation (e.g., info about thecustomer, info about the product).

Provide sufficient room to record eachitem.

Order the data items consistent withthe sequence in which the data islikely to be gathered.

Use codes and check-offs in placeswhere standardized explanations arelikely.

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

Forms Design






Main body of form

Conclusion section of form

Provide space for: Recording final disposition of the

form.

Approval signatures.

Dates of approval and final

disposition. A dollar or numeric total.

Clearly indicate the distribution ofeach form.

PHYSICAL SYSTEMS


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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, its important to design computer screens for input as

well as output.

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

Computer screens are most effective when the followingprinciples are used:

Organize the screen for quick, accurate, and complete entry of

the data.

Minimize input by retrieving as much as possiblefrom the system.

Example: If the customer number is entered,retrieve his name/address data from the system.


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Systems

Analysis

Conceptual

Systems

Design

OutputDesign

Implementation

and

Conversion

Operation

and

Maintenance

File and DBDesign

InputDesign

ProgramDesign

Proce-dures

Design

ControlsDesign

PHYSICAL SYSTEMS


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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

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN


Input medium Keyboard

OCR

MICR

POS terminal EDI

Voice input

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN


Input medium

Input source

Where do dataoriginate?

Computer

Customer Remote location

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN


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

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN


Input medium

Input source

Input format

Input type What is the nature of the

data?

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN


Input medium

Input source

Input format

Input type

Volume How much data are to be

entered?

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN


Input medium

Input source

Input format

Input type

Volume

Personnel

What functions and expertise do thedata entry operators have?

Is additional training necessary?

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN


Input medium

Input source

Input format

Input type

Volume

Personnel

Frequency

How often is data to beentered?

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN


Input medium

Input source

Input format

Input type

Volume

Personnel

Frequency

Cost How can costs be minimizedwithout adversely affectingefficiency and accuracy?

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN


Input medium

Input source

Input format

Input type

Volume

Personnel

Frequency

Cost

Error detection and correction

What errors are possible? How can they be detected and

corrected?

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

Forms design





Preprint as much data as possible.

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

requirements for filing, binding, or mailing.

If mailed to external parties, position the addressfor placement in a window envelope.

Have copies of the form printed in different colorsto facilitate accurate distribution.

Include clear instructions for completing the form.

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

Forms design




evaluating existing ones:

General considerations


Place the form name at the top in bold

type. Have the forms pre-numbered

consecutively.

If distributed to external parties, havecompany name and address pre-

printed on the form.

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

Forms design







Main body of form

Group together logically relatedinformation (e.g., info about thecustomer, info about the product).

Provide sufficient room to record eachitem.

Order the data items consistent withthe sequence in which the data islikely to be gathered.

Use codes and check-offs in places

where standardized explanations arelikely.

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

Forms Design







Main body of form

Conclusion section of form

Provide space for: Recording final disposition of the

form.

Approval signatures.

Dates of approval and final

disposition. A dollar or numeric total.

Clearly indicate the distribution ofeach form.

PHYSICAL SYSTEMS


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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, its important to design computer screens for input as

well as output.

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

Computer screens are most effective when the followingprinciples are used:

Organize the screen for quick, accurate, and complete entry of

the data.

Minimize input by retrieving as much as possiblefrom the system.

Example: If the customer number is entered,retrieve his name/address data from the system.

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

Program design

Program development is one of the most time-consuming

activities in the SDLC.

A st ructured programm ingprocess should be followed:

With structured programming, programs should be subdivided intosmall, 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 onlyone entry and exit point.

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

To improve software quality, organizations shoulddevelop programming standards (rules for writing

programs).

Contributes to consistency among programs.

Makes them easier to read and maintain.

Consider doing structured program walk-throughs to

find incorrect logic, errors, omissions, or other

problems.

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

Program preparation time may range from a fewdays 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.

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

STEP ONE: Determine user needs.

Occurs during the systems analysis stage of

the SDLC.

SystemsAnalysis

Conceptual

Design

Physical

Design

Implementation

and

Conversion

Operation

and

Maintenance

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

STEP TWO: Develop and document aplan.

Occurs during the conceptual design phase

and the beginning of physical design.

SystemsAnalysis

Conceptual

Design

Physical

Design

Implementation

and

Conversion

Operation

and

Maintenance

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PHYSICAL SYSTEMS

DESIGN

STEP THREE: Write the program code.

Design in increasing levels of detail, known

as hierarchical prog ram design.

Begun during systems design and completed

during systems implementation.

SystemsAnalysis

Conceptual

Design

Physical

Design

Implementation

and

Conversion

Operation

and

Maintenance

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

STEP FOUR: Test the program code.

Debuggingis discovering and eliminating

program errors.

Desk checkinghappens after a program is

coded and involves a visual and mentalreview to discover programming errors.

Programs are tested for logic errors using

test data that simulates both valid

transactions and all possible error conditions.

SystemsAnalysis

Conceptual

Design

Physical

Design

Implementation

andConversion

Operation

and

Maintenance

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

Large programs are often tested in threestages:

Individual program modules.

The linkages between the module and the

control module.

The interfaces between the program beingtested and other application programs.

SystemsAnalysis

Conceptual

Design

Physical

Design

Implementation

andConversion

Operation

and

Maintenance

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

Errors need to be found as soon as possible inthe development process.

Errors discovered late cost 801000% more to

fix than those found early.

SystemsAnalysis

Conceptual

Design

Physical

Design

Implementation

andConversion

Operation

and

Maintenance

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

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, narrativedescriptions of the system, etc., organized in a

manual.

SystemsAnalysis

Conceptual

Design

Physical

Design

Implementation

andConversion

Operation

and

Maintenance

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

STEP SIX: Train program users.

Often uses the program documentation.

SystemsAnalysis

Conceptual

Design

Physical

Design

Implementation

andConversion

Operation

and

Maintenance

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

STEP SEVEN: Install the system.

-All components are brought together, and the

company begins to use the system.

SystemsAnalysis

Conceptual

Design

Physical

Design

Implementation

andConversion

Operation

and

Maintenance

PHYSICAL SYSTEMS


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PHYSICAL SYSTEMS

DESIGN

STEP EIGHT: Use and modify the system. Program maintenanceis a response to any

factors that require program revision.

Includes requests for:

New or revised reports.

Changes in input, file content, or values suchas tax rates.

Error detection and correction.

Conversion to new hardware.

SystemsAnalysis

Conceptual

Design

Physical

Design

Implementation

andConversion

Operation

and

Maintenance


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Systems

Analysis

Conceptual

Systems

Design

OutputDesign

Implementation

and

Conversion

Operation

and

Maintenance

File and DBDesign

InputDesign

ProgramDesign

Proce-

dures

Design

ControlsDesign

PHYSICAL SYSTEMS


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C

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

PHYSICAL SYSTEMS


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DESIGN

Procedures may take the form of:

System manuals

User instruction classes

Training materials

Online help screens

PHYSICAL SYSTEMS


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DESIGN

The procedures may be written by:

Development teams;

Users; or

Teams representing both groups.

S t


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Systems

Analysis

Conceptual

Systems

Design

OutputDesign

Implementation

and

Conversion

Operation

and

Maintenance

File and DBDesign

InputDesign

ProgramDesign

Proce-

duresDesign

ControlsDesign

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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.

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DESIGN

Important control concerns that must be addressedinclude:

Validity Are all interactionsvalid?

PHYSICAL SYSTEMS


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DESIGN


Validity

Authorization

Are input, processing, storage, andoutput activities authorized by theappropriate managers?

PHYSICAL SYSTEMS


104/111

DESIGN


Validity

Authorization

Accuracy Is input verified to ensure

accuracy?

What controls ensure that data isnot lost when passing betweenprocessing activities?

PHYSICAL SYSTEMS


105/111

DESIGN


Validity

Authorization

Accuracy

Security

Is the system protected against:

Unauthorized physical and logical access toprevent improper use, alteration, destruction,or disclosure of information and software?

Theft of system resources?

PHYSICAL SYSTEMS


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DESIGN


Validity

Authorization

Accuracy

Security

Numerical control

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

PHYSICAL SYSTEMS


107/111

DESIGN


Validity

Authorization

Accuracy

Security

Numerical control

Availability

Is the system available as set forth inagreements?

Can users enter, update, and retrieve data duringthose times?

PHYSICAL SYSTEMS


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DESIGN


Validity

Authorization

Accuracy

Security

Numerical control

Availability

Maintainability

Can the system be modified without affecting

system availability, security, and integrity? Are only authorized, tested, and documented

changes made to the system and data?

Are resources available to manage, schedule,document, and communicate changes tomanagement and authorized users?

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DESIGN


Validity

Authorization

Accuracy

Security

Numerical control

Availability

Maintainability Integrity

Is processing complete, accurate,timely, and authorized?

Is it free from unauthorized orinadvertent manipulations?

PHYSICAL SYSTEMS


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DESIGN


Validity

Authorization

Accuracy Security

Numerical control

Availability

Maintainability

Integrity Audit trail

Can data be traced from source to output and viceversa?

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DESIGN

Physical systems design report

At the end of the physical design phase, a phys ica l sys tems

design repor tis prepared, summarizing what was accomplished.

This report serves as the basis for managements decision whether

to proceed to implementation.

Documents

Dac3193 - Accounting Information System II