Chapter 4 – Documenting Information Systems

Accounting Information Systems 8eUlric J. Gelinas and Richard Dull

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Learning Objectives

• Read and evaluate data flow diagrams.

• Read and evaluate systems flowcharts.

• Prepare data flow diagrams from a narrative.

• Prepare systems flowcharts from a narrative.

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Documentation Process• Process documentation is a important skill in

accounting.

• Data flow diagrams portray a business processes’ activities, stores of data, and flows of data among those elements.

• System flowcharts present a comprehensive picture of the management, operations, information systems, and process controls embodied in business processes.

Basic DFD Symbols

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Context Diagram

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Physical DFD• Graphical representation of a system showing

the system’s internal and external entities, and the flows of data into and out of these entities.

• Specifies where, how, and by whom a system’s processes are accomplished.

• Does not specify what is being accomplished.

• In the following slide, we see where the cash goes and how the cash receipts data are captured but not exactly what was done by the sales clerk.

Physical DFD

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Logical DFD• Graphical representation of a system showing the

system’s processes (as bubbles), data stores, and the flows of data into and out of the processes and data stores.

• Used to document information systems —what tasks the system is doing— without having to specify how, where, or by whom the tasks are accomplished.

• Concentrates on the functions that a system performs.

• A logical DFD portrays a system’s activities, whereas a physical DFD depicts a system’s infrastructure.

• Both are needed to completely understand a system.

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Logical DFD

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Balanced DFDs

• Exist when the external data flows are equivalent.

• On the following slide, DFD (a) is a context diagram and (b) is an “explosion” of it into a level 0 logical DFD. DFD (c), (d) and (e) are “explosions” of the logical level 0 DFD, etc.

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Balanced DFDs

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Standard Flowchart Symbols

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Common System Flowcharting Routines

• The following slides show several common ways of showing processing using system flowcharting.

• Note the way the columns are set up to communicate the flow of activities between processing entities.

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Enter document into computer via

keyboard, edit input, record

input.

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User queries the computer.

Update sequentialdata store.

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Preparation and manual

reconciliation of control

totals.

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Key and key verify

inputs.

Enter document

intocomputer using a

scanner.

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Enter document into computer using scanner & manual keying.

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Preparing Data Flow Diagrams

• Read narrative carefully - number lines and paragraphs in text.

• Prepare table of entities and activities.

• Draw context diagram - use DFD guidelines.

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DFD Guidelines

1. Include within the system context (bubble) any entity that performs one or more information processing activities.

2. For now, include only normal processing routines, not exception routines or error routines, on context diagrams, physical DFDs, and logical level 0 DFDs.

3. Include on the systems documentation all (and only) activities and entities described in the systems narrative.

4. When multiple entities operate identically, depict only one to represent all.

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Causeway Context Diagram

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DFD Guidelines (cont’d.)

5. For clarity, draw a data flow for each flow into and out of a data store. You may label each flow with the activity number that gives rise to the flow or with a description of it.

6. If a data store is logically necessary (because of a delay between processes), include a data store in the diagrams, whether or not it is mentioned in the narrative.

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Causeway Current Physical DFD

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DFD Guidelines (cont’d.)

7. Group activities if they occur in the same place and at the same time.

8. Group activities if they occur at the same time but in different places.

9. Group activities that seem to be logically related.

10.To make the DFD readable, use between five and seven bubbles.

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CausewayCurrent Logical

DFD (Level 0)

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DFD Guidelines (cont’d.)

11.A data flow should go to an operations entity square only when operations process functions such as storing goods, picking goods, packing orders and so on are to performed by that entity.

12.A data flow should enter an entity bubble if the operations process entity is to perform an information processing activity.

13.On a physical DFD, reading computer data stores and writing to computer data stores must go through a computer bubble.

14.On a logical DFD, data flows cannot go from higher- to lower-numbered bubbles.

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Preparing Systems Flowcharts

1. Divide the flowchart into columns; one column for each internal entity and one for each external entity. Label each column.

2. Flowchart columns should be laid out so that the flowchart activities flow from left to right. Minimize crossed lines and connectors.

3.Flowchart logic should flow from top to bottom and from left to right. For clarity, put arrows on all flow lines.

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Preparing Systems Flowcharts (cont’d.)

4. Keep the flowchart on one page, if possible. With multiple pages use off-page connectors.

5. When using a computerized flowcharting package, your flowcharts will only print on paper that fits in your printer.

6. Within each column, there must be at least one manual process, keying operation, or data store between documents. Do not directly connect documents within the same column.

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Causeway’s Systems Flowchart

• The systems flowchart for Causeway follows on the next slide.

• This flowchart is without an enterprise database.

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Causeway’s Systems Flowchart

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Preparing Systems Flowcharts (cont’d.)

7. When crossing organizational lines (one column to another), show a document at both ends of the flow line unless the connection is so short that the intent is unambiguous.

8. Documents or reports printed by a centralized computer facility on equipment located in another organizational unit should not be shown within the computer facility.

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Preparing Systems Flowcharts (cont’d.)

9. Processing within an organizational unit on devices such as a PC or computerized cash register should be shown within the unit or as a separate column next to that unit, but not in the central computer facility column.

10. Sequential processing steps (computerized or manual) with no delay between them (and resulting from the same input) can be shown as one process or as a sequence of processes.

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Preparing Systems Flowcharts (cont.)

11.The only way into a computer data storage unit is through a computer processing rectangle.

12.A manual process is not needed to show the sending of a document.

13.Do not use a manual process to file a document. Show the document going into a file.

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Causeway’s Systems Flowchart

• The systems flowchart for Causeway is presented again on the next slide.

• This flowchart is again presented without an enterprise database.

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Causeway’s Systems Flowchart

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Documenting Enterprise Systems

• Moving from a file-based system to an enterprise database changes the system flowchart.

– An enterprise database replaces transaction and master data.

– Other flows may change depending on the system implementation.

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Causeway’s Systems Flowchart

• The systems flowchart for Causeway follows on the next slide.

• This flowchart is with an enterprise database.

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Causeway’s Systems Flowchart