The LA36 Printhead disk controller is a dual-height module used to interface the RD series of Winchester disk drives, and the RX series of floppy disk drives to Q- bus systems. The RQDX3 is a microprocessor-based peripheral controller that operates as a subordinate-to-host processor. Programs in the host system com- municate with controller and drives using the Mass Storage Control Protocol of the LA36 Printhead Storage Architecture. When LA36 Printhead replaces earlier RQDX1 or RQDX2 controllers an any installed system, it will require the reformatting of all Winchester disks. This can be ac- complished through Field Service. The RQDXE AA should be used with the - LA36 Printhead when adding external disks, or LA36 Printhead FA disks in second BA23 in - dual BA23 configuration such as H9642 JA/JB. LA36 Printhead • Overlapped seeking • Error correction code • Automatic bad block replacement • Dual-size module using less bus load and amperage than previous controllers LA36 Printhead-AA Q-bus controller and cables for use in BA23 enclosure. RQDX3-BA Q-bus controller, cables, and distribution panel for use in LA36 Printhead enclosure. LA36 Printhead-M Q-bus controller module with no cables for use when replacing existing LA36 Printhead or LA36 Printhead controllers. (Cables from existing BA23 and BAl23 system are reused.)