A uniform, flexible approach is proposed for analysing the feasibility of deadline scheduled real-time systems. In its most general formulation, the analysis assumes sporadically periodic tasks with arbitrary deadlines, release jitter, and shared resources. System overheads of a tick driven scheduler implementation, and scheduling of soft aperiodic tasks are also accounted for. A procedure for the computation of task worst-case response times is also described for the same model. While this problem has been largely studied in the context of fixed priority systems, we are not aware of other works that have proposed a solution to it when deadline scheduling is assumed. The worst-case response time evaluation is a fundamental tool for analysing {\em end-to-end} timing constraints in distributed systems~\cite{Ti94b}.