Wikipedia
Massbus
The Massbus is a high-performance computer input/output bus designed in the 1970s by the Digital Equipment Corporation of Maynard, Massachusetts.
The bus was used by Digital to interconnect its highest-performance computers with magnetic disk and magnetic tape storage equipment. The use of a common bus allowed the PDP-10, PDP-11, and VAX computer families to share a common set of peripherals. An additional business objective was to provide a subsystem entry price well below that of IBM storage subsystems which used large and expensive controllers unique to each storage technology and optimized for connecting large numbers of storage devices.