An engineering goal was to reduce the need for a new driver per peripheral per operating system per computer family.
Also, a major technical goal was to place any magnetic technology changes (data separators) into the storage device rather than in the CPU-attached controller.
The first Massbus device was the RP04, based on Sperry Univac Information Storage Systems's (ISS) clone of the IBM 3330.
Memorex modified the IBM compatible interface to DEC requirements and moved the data separator electronics into the drive.
DEC also developed the Massbus RS03/04, a head per track disk drive for high performance swapping.