RQDX Series of MFM Disk & Floppy QBUS Controllers
From Computer History Wiki
The series of the RQDX MFM Disk & Floppy QBUS Controllers:
was created for the series of MicroPDP computers, the MicroVAX I, and the MicroVAX II.
Although not standard, the RQDX controllers can also be used with later QBUS-based MicroVAX models.
Depending on the version of the RQDX controllers and their firmware, they supported the following fixed disk and floppy drives: