RP10 disk controller
From Computer History Wiki
The RP10 disk controller is a disk device controller for the PDP-10, primarily for the early models (KA10 and KI10) which had the PDP-10 I/O bus as a standard bus.
It works with the RP01, RP02 and RP03 disk drives; up to 8 drives per controller. It is paired with a DF10 Data Channel unit which performs DMA to main memory.
The RP10 has the ability to perform seeks on multiple drives simultaneously.