\section{Introduction}

Our world is getting more and more surrounded by electronic devices. Only a few years ago our surroundings were limited to radio's and televisions. Soon after we got our microwaves and washing machines, not to mention the boom in the mobile phone corner. All these devices require operating systems and nearly all of these OS require real-time computations. \\

To define a real-time operating system is beyond the scope of this article, what is not however is that all (real-time) operating systems use some sort of scheduling algorithm. \\

We have done a literature study concerning one of these algorithms, called Fixed Priority Scheduling with Deferred Preemtion (FPDS) and looked at various aspects of it. In chapter 2 we discuss development considerations while the architectural considerations are dealt with in chapter 3. The next chapter, chapter 4, is all about the application domains of FPDS. We conclude our report with some small results and notes on the discussion held after our presentation on this subject.

\section{Motivation}

Fixed priority scheduling with preemption (FPPS) is already widely used. In the case of FPPS with the use of cash brings great unpredictability. Caches are great for performance improvements, if you can use them. Audio/Video almost always work a lot faster with caches. So if you like to use caches in a real-time system, there is a scheduling algorithm that allows exactly this, namely is FPDS. FPDS allows the uses of caches, and still behaves like a real-time system. \\

Resource control can get complex very fast, due to things like Interrupt Service Routines (ISR) and buffers to actually access certain resources. With FPPS this is very complex task and introduces a lot of overhead. One of the design goals of FPDS was to simply this and thus also reducing the overhead.
