Why Does The Software Design Differ From Real Time System Design?

The design process for real time systems differs from other software design processes because the system response times must be considered early in the process. Events (the stimuli) rather than objects or functions should be central to the design process. There are several stages in this design process:-

1-Identify the stimuli that the system must process and the associated responses.

2-For each stimulus and associated responses, identify the timing constraints which apply to both stimulus and response processing.

3-Aggregate the stimulus and response processing into a number of concurrent processes. A good model for the system architecture is to associate a process with each class of stimulus and response.

4-For each stimulus and response, design algorithm to carry out the required computations. Algorithm designs often have to be developed relatively early in the design process to give an indication of the amount of processing required and the time to complete that processing.

5-Design a scheduling system which will ensure that processes are started in time to meet their deadlines.

6-Integrate the system under the control of a real time executive.

Naturally, this is an iterative process. The process architecture has been established and scheduling process has been decided extensive assessment and stimulations are needed to check that the system will meet its timing constraints.