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3.2 revision - Coggle Diagram
3.2 revision
Physical data flow
A PDFD is a graphical representation of how data flows throuhg a system
Data Source
The source of data
Internal Entity
Internal entites are a way to define replacement values.
Input
data inputted in preparation for processing
Processing
transforming data into meaningful output
Feedback Loop
a system structure that allows output to influence future input
Hierarchy
A Hierarchy refers to an a organised structure that ranks the level of importance.
External Entity
External entites can acess local or remote content by a declaed system identifier.
Storage
recording and saving of data on an suitable format:
Logical data flow
the logical data flow describes the business events that take place and the data required for each event.
Abstration
Abstraction is the process of removing unessary information.
Output
data generated by the information system
Data Flow
Data flow is used to describe how data moves between sub-programs.
Process
Is a instance of a program running in a computer