The same serial interconnect was used for tape and solid state storage devices to connect primarily the Hierarchical Storage Controller (HSC) series but Unibus and BI Bus controllers to SDI were built as well.
The same serial interconnect was used for tape and solid state storage devices to the storage subsystem controllers. Large VAX systems primarily used the Hierarchical Storage Controller (HSC) series but Unibus and BI Bus controllers to SDI were built as well.