
Students Guide to Information
Technology
may require to do some modelling of the current technology just to
find out what's going on, Yourdon recommends that the analyst
starts,
as quickly as possible, to develop the new logical model He
calls this the
essential
model of the system.
The essential model
The essential model shows what the system must do to achieve the
user's requirements, but it includes no implementation details (i.e.
it says nothing about the technology to be employed, manual
procedures, etc.). The model assumes perfect technology, so it also
omits procedures that arise from imperfect technology, such as
error checking. Al