Morrow - Disk Jockey Winchester Hard Disk Controller
This was a brilliantly designed S-100 Hard disk controller board. Doing on one board what others often took 2 boards to do.

The Disk Jockey Winchester Hard Disk Controller (HDCA), when combined with a Morrow Designs Winchester-type hard disk drive and a power supply, provided the user with a complete Morrow Designs Discus M26, M20 or M10 mass storage system- The Discus M26 drive offered 26 MB of formatted storage capacity; the M20 drive was a 20MB  drive, and the M10 was a 10MB disk drive. The HDCA controller plugged into any S-100 slot of the motherboard in an S-100 system, and was connected to the drive through a pair of flat cables. One of the cables carries clock and data information, and the other carried control and status information.
 
The controller could accommodate up to four drives of the same type, so the M26 system could be expanded to a total capacity of 104 million bytes, the M20 to over 80 million bytes and the M10 to over  40 million. Morrow Designs supplied the system with CP/M, but also configured the HDCA to run Micronix, Morrow Designs' multi-user operating system. 
 
The DIP switch allowed you to set the boards base port -- normally 50H-53H.
  
The manual for this board can be obtained here.