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The real-time token-based RTnet network protocol has been implemented on a standard Ethernet network to investigate the possibility to use cheap components with strict resource limitations while preserving Quality of Service guarantees. It will be shown that the proposed implementation is feasible on a small network. For larger networks a different approach is necessary, using delegation by means of proxies. A delegation proposal will be discussed. For small networks it is possible to use a PIC microcontroller in combination with a standard Ethernet controller to run the RTnet network protocol. As more systems are added to the network the performance of this combination becomes insufficient. When this happens it is necessary for the microcontroller to delegate some tasks to a more powerful master and to organize a low-level communication protocol between master and slave.

This paper compares the implementation results of two architectures for virtual channel router. Since the router is used for building an on-chip network, its small size is critical. Together with the total design area we provide information about the distribution of this area between the main router blocks and thus give insight about the cost of each block. The comparison shows that one of the architectures results in smaller implementation area and overcomes some performance problems presented by the other architecture.

The design for a new type of non-volatile mass storage memory is discussed. This new design, based on scanning probe techniques, combines the low volume and power consumption of the FlashRAM, with the high capacity of the hard disk. The small form factor of the device makes it an excellent candidate for mass storage in handheld embedded systems. Its hierarchical architecture allows us to make a trade-off between data-rate, access time and power consumption. The power consumption scales linearly with the desired data-rate, and is expected to be lower than what can be achieved with competing technologies.

We present a jukebox scheduler for real-time data. The scheduler is part of a hierarchical real-time file system to be used over a network. A jukebox is a large tertiary storage device whose removable media (e.g. cd-rom, dvd-rom) are loaded and unloaded from one or more drives by a robot. The problem with tertiary storage is that media exchange times are high and the number of drives is limited. This makes scheduling tertiary storage complicated. The storage media switching time in a jukebox is in the order of tens of seconds. Therefore multiplexing between two files stored in different media is many orders of magnitude slower than doing the same in secondary storage. The goal of the scheduler is to schedule the use of the jukebox devices (arm and drives) in such a way that the system can guarantee the deadlines while minimizing the response time. The problem is similar to that of scheduling multiple processors with the additional difficulty of having to deal with the high switching times and the use of a shared resource (the arm). Finding an optimal schedule is an NP-hard problem. We provide a near-optimal polynomial solution by using heuristics to prune the tree of solutions. The scheduling time is in average less than 100 ms. The incoming requests are scheduled on-line.