The stream processor is usually equipped with a fast, efficient, proprietary memory bus (crossbar switches are now common, multi-buses have been employed in the past).
For overvoltage protection the whole powerline is equipped with two ground conductors, which are installed on a separate crossbar on the top of the pylons.
The crossbar switch itself was simple: exchange design moved all the logical decision-making to the common control elements, which were very reliable as relay sets.
