All 3?
I was asked to draw a DFD, instead of drawing a Dataflow Diagram, I started drawing a
Context Diagram. It started to become complicated so I knew I was on the wrong track (imagine having a context diagram that is so complicated it looked like a System Flowchart + Dataflow Diagram + Context Diagram all in 1 LOL!).
So I didn't answer that question and moved onto the theory.
Dataflow diagrams are meant to represent the system with all inputs, outputs and storage requirements. System flowcharts on the other hand, will only show the flow of data and the logic of the system. Now, you've got 1 out of the 2 (SFC and DFD's both represent the system and the flow of data, so that's 50% covered), but on the other hand, the System flowchart shows the logic of the system, which wasn't asked.
If I was generous, I'd give you 1 out of the 3.
If I was sticking to the marking guideline (for example one of the criteria that examiners might use would be "uses correct symbols"). So they'll be expecting to see the external entities, the processes and the data stores, which aren't in the System Flowchart at all.
So re-evaluating my stance, I'd say 0/3
While it is true that SFC's demonstrate the flow of data in a system, the symbols that are used are not required (or necessary) in DFD's, which is primarily what the examiners want to see, the proper data flows, external entities, data stores, labelling, etc.
1 mark correct labelling
2 marks use of correct symbols e.g. external entities and datastores, as well as processes and data flows (arrows).
Look on the bright side,
I missed the question completely, so you're better off than I am
