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And aftermarket vendors such as In2games are launching accelerometer-based controllers to bring Wii-like functionality to existing consoles. Think guns, light sabers, hand grenades, bazookas—it's all on the table here.

Many generations of silicon devices have leveraged this virtuous cycle. Unfortunately, the rate of increase in single-processor performance has leveled off substantially. The most important contributing factor to this decline has been power. Smaller transistors led to faster switching times. Shrinking transistors made them leakier, which lead to increasing static power. And as transistors switch faster, dynamic power increases.

This spiraling power increase highlighted several realities driven by the physics of current silicon process technology. First, individual processor performance will be limited by how much power can be supplied and dissipated in a system. Second, transistor budgets will continue to increase but achievable clock rates will not.

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With still-growing transistor budgets, the industry has moved quickly to devices with multiple processor cores that also integrate memory controllers, application accelerators and I/O interfaces to form a multicore SoC. Multicore devices promise significantly increased system performance.

The rise of SoC devices has reduced the boundaries between individual components and the system architectures they implement. Where once a board held one complete computing system, today many such systems are present on a single device.

The transition to SoC devices changes the requirements for interconnects used between SoCs and other devices and networks. Board and system-level interconnects were initially shared bus-based. As with past processors, the demand for more interconnect performance was addressed in a similar fashion: Increase the clock rate and widen bus widths. As with processors, physics eventually intervened, demanding that the number of devices on the bus be reduced. This led to bus segmentation, hierarchical topologies and, ultimately, point-to-point, switch-based networks.

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Embedded systems are often partitioned into three subsystem functions: control plane, data plane and system management. When a system consisted of one computing system, the number of system-level traffic streams was limited. This was fortunate, because available bus-based interconnects by definition accommodate just a single traffic stream.

To improve system performance, a dedicated processor was applied to each function. This quickly introduced quality-of-service (QoS) issues as multiple concurrent communication streams arose. In many cases, three separate interconnects were used to better optimize bandwidth and prevent undesirable interaction between individual streams. In these systems, each processor performs a single function and is responsible for a single or at most a handful of traffic streams.

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However, a multicore SoC dramatically changes this picture. Many streams of traffic per chip can now be expected as each core handles its own streams.

Expect the near-term challenge of parallelizing existing code to drive the convergence of control, data and management plane functions onto a single multicore SoC as a stopgap use of multicore architectures. This will give rise to at least three and likely more streams on a four-core device. In the longer term, software will become multi-core-friendly and swing back to many cores performing discrete data or control plane functions. In either case, multiple traffic streams will be present wherever multicore SoCs are employed. With future SoCs using 8, 16 and even more cores, the number of streams supported by a single device will grow substantially in the next two to four years.

The majority of MOST systems on the road today do not transport video digitally. The main reason is that it was forbidden to send DVD content digitally over any network and hybrid systems with both analog and digital video were not economically feasible. With the integration of DVD Audio and DVD Video into digital networks, the requirement for content protection comes into place. DVD content on a digital network must be DTCP (Digital Transmission Content Protection) protected.

The vehicle architectures were already defined and being rolled out without digital video when, in 2003, MOST was the first network to be fully approved by the DVD Copy Control Association (DVD CCA) to carry DTCP protected content. This was made possible by adapting DTCP to the MOST standard. By doing so, also HD-DVD and Blu-ray content on MOST is supported since AACS (Advanced Access Content System) licensing allows digital outputs which are protected using DTCP. DTCP requires source and sink devices to authenticate each other. In addition, there is a need to encrypt multimedia streaming data before sending it over a digital network. A sink device therefore has to be able to decrypt protected digital content. DTCP on MOST also supports point-to-multipoint connections.

Fig. 3. For aftersales software updates, diagnosis functions and the integration of portable consumer devices, the system offers connectivity to Ethernet and USB.


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