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The developers of SSADM understood that in almost all cases there is some form of current system even if it is entirely composed of people and paper. Through a combination of interviewing employees, circulating questionnaires, observations and existing documentation, the analyst comes to full understanding of the system as it is at the start of the project. This serves many purposes:
*the analyst learns the terminology of the business, what users do and how they do it
*the old system provides the core requirements for the new system
*faults, errors and areas of inefficiency are highlighted and their correction added to the requirements
*the data model can be constructed
*the users become involved and learn the techniques and models of the analyst
*the boundaries of the system can be defined
The products of this stage are:
*Users Catalogue describing all the users of the system and how they interact with it
*Requirements Catalogue detailing all the requirements of the new system
*Current Services Description further composed of
*Current environment Logical Data Model
*Context diagram ([[Data flow diagram|DFD]])
*Leveled set of [[Data flow diagram|DFDs]] for current logical system
*Full data dictionary including relationship between data stores and entities
To produce the models, the analyst works through the construction of the models as we have described. However, the first set of data-flow diagrams ([[Data flow diagram|DFDs]]) are the current physical model, that is, with full details of how the old system is implemented. The final version is the current logical model which is essentially the same as the current physical but with all reference to implementation removed together with any redundancies such as repetition of the information that makes up the users and requirements catalogues.
=== Stage 2 – Business system options ===
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