Documenting
Information
Systems
Learning Objectives
• To read and evaluate data
flow diagrams
• To read and evaluate
systems flowcharts.
• To prepare data flow
diagrams from a narrative.
• To prepare systems
flowcharts from a narrative.
Documenting
Information
Systems
Documenting Processes on the
AIS Wheel
• Process documentation is a important
skill in accounting
• You will learn that data flow diagrams
portray a business processes’ activities,
stores of data, and flows of data among
those elements.
• Systems flowcharts, on the other hand,
present a comprehensive picture of the
management, operations, information
systems, and process controls
embodied in business processes.
3
Basic DFD Symbols
4
CONTEXT DIAGRAM
5
Physical DFD
• A physical data flow diagram is a graphical
representation of a system showing the
system’s internal and external entities, and
the flows of data into and out of these entities.
– A physical DFD specifies where, how, and by
whom a system’s processes are accomplished.
– A physical DFD does not tell us what is being
accomplished.
– In the following slide, we see where the cash goes
and how the cash receipts data are captured (that
is, on the register tape), but we don’t know exactly
what was done by the sales clerk.
6
Physical DFD
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Logical DFD
• A logical data flow diagram is a 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.
– We use a logical DFD to document information systems
because we can represent the logical nature of a system—
what tasks the system is doing— without having to specify
how, where, or by whom the tasks are accomplished.
– The advantage of a logical DFD (versus a physical DFD) is
that we can concentrate on the functions that a system
performs.
– So, a logical DFD portrays a system’s activities, whereas a
physical DFD depicts a system’s infrastructure.
– We need both pictures to understand a system completely.
8
Logical
DFD
9
Balanced DFDs
• The next slide depicts “balanced” data flow
diagrams.
• Balanced DFDs exist when the external
data flows are equivalent.
• 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, and so on.
10
Balanced
DFDs
11
Standard
Flowchart
Symbols
12
Common system flowcharting
routines
• The following slides show several
common ways of showing
processing using system
flowcharting.
• Pay particular attention to the way
the columns are set up to
communicate the flow of activities
between processing entities.
13
Enter document into computer
via keyboard, edit input,
record input
14
User queries the
computer
Update sequential
data store
15
PREPARATION AND LATER
MANUAL
RECONCILIATION OF
CONTROL TOTALS
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KEY AND KEY
VERIFY INPUTS
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Enter
document into
computer
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 - no more, no less.
• 4. When multiple entities operate identically, depict
only one to represent all.
21
Causeway Context Diagram
22
DFD Guidelines (cont.)
• 5. For clarity, draw a data flow for each flow into
and out of a data store. You may, also for clarity to
help you determine that you have included all
necessary flows, label each flow with the activity
number that gives rise to the flow or with a
description of the flow.
• 6. If a data store is logically necessary (that is,
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.)
• 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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Causeway
Logical
Level 0
DFD
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DFD Guidelines (cont,)
• 11. A data flow should go to an operations entity square
only when operations process functions (that is, workrelated functions such as storing goods, picking goods
from shelves, packing the customer’s order and so on) are
to performed by that entity. A data flow should enter an
entity bubble if the operations process entity is to perform
an information processing activity.
• 12. On a physical DFD, reading computer data stores and
writing to computer data stores must go through a
computer bubble.
• 13. On a logical DFD, data flows cannot go from higher- to
lower-numbered bubbles.
27
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, but
you should locate columns so as to minimize
crossed lines and connectors.
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System flowcharting guidelines
(cont.)
• 3. Flowchart logic should flow from top to bottom
and from left to right. For clarity, put arrows on all
flow lines.
• 4. Keep the flowchart on one page. If you can’t,
use multiple pages and connect the pages with
off-page connectors. Computerized flowcharting
packages will print your flowcharts only on paper
that will fit in your printer!
29
Causeway’s Systems Flowchart
• The systems flowchart for Causeway
follows on the next slide
• This flowchart for causeway is without
an enterprise database
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System flowcharting guidelines
(cont.)
• 5. Within each column, there must be at least one
manual process, keying operation, or data store
between documents. That is, do not directly
connect documents within the same column.
• 6. 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.
32
System flowcharting guidelines
(cont.)
• 7. Documents or reports printed in a computer
facility should be shown in that facility’s column
first. You can then show the document or report
going to the destination unit.
• 8. Documents or reports printed by a centralized
computer facility on equipment located in another
organizational unit ( warehouse, shipping dept.)
should not be shown within the computer facility.
33
System flowcharting guidelines
(cont.)
• 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.
34
System flowcharting guidelines
(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. The sending of the
document should be apparent from the movement
of the document itself.
• 13. Do not use a manual process to file a
document. Just show the document going in to a
file.
35
Causeway’s Systems Flowchart
• The systems flowchart for Causeway is
presented again on the next slide
• This flowchart for causeway is again
presented without an enterprise
database
36
37
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
38
Causeway’s Systems Flowchart
• The systems flowchart for Causeway
follows on the next slide
• This flowchart for causeway is with an
enterprise database
39
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