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Systems Analysis and DFDs

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Systems Analysis and DFDs Systems Life Cycle concept Systems Analysis Importance of Systems Analysis Data flow diagram (DFD) Leveling DFDs Exploding DFDs National ... – PowerPoint PPT presentation

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Title: Systems Analysis and DFDs


1
  • Systems Analysis and DFDs

2
  • Systems Life Cycle concept

3
  • Systems Analysis

4
  • Importance of Systems Analysis
  • determines the CONTENT of an MIS
  • represents 25 of the MIS development effort
  • relates to performance
  • higher budget compliance
  • higher satisfaction

5
  • Data flow diagram (DFD)

6
  • Leveling DFDs

How to factor a system?
  • The BLACK BOX concept
  • you know the inputs it expects
  • you know the outputs it should give back
  • you know its function (what it does)
  • you do not need to know the specifics to use it
  • Controlling complexity of black boxes
  • each box should solve one well-defined piece of
    the problem
  • each box should be easy to understand
  • connections should be made as simple as possible

7
  • Exploding DFDs

8
  • National Merchandising Case

9
  • Second level

purchase order
accounts payable
vendor account
accounts
invoice
check
3.0
2.0
1.0
due
write
revise
Invoice
Vendor
Vendor
vendor
balance
approval
checks
due
checking account
payable invoices
10
  • Third level

11
  • Third level - continued

12
  • Third level - end
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