KDA50-Q User Guide

This document is a User Guide (Semi-Final Review) for the KDA50-Q Disk Controller, manufactured by Digital Equipment Corporation in November 1984.

The KDA50-Q is an intelligent disk controller designed to connect up to four 16-bit RA series disk drives to any CPU that operates on a QBUS. It is built from two quad-height modules: the M7164 (Processor Module), which handles QBUS interaction and microcode processing, and the M7165 (SDI Module), which serves as the communication interface to the disk drives, featuring a 32K byte buffer and Error Correction Code (ECC) generation.

The controller implements Digital Storage Architecture (DSA) and utilizes the Standard Disk Interconnect (SDI), employing a radial bus configuration (a separate I/O cable for each disk drive). It communicates using the Mass Storage Control Protocol (MSCP), which offloads I/O management from the host and abstracts disk geometry, presenting the disk as logical blocks. The controller's functional microcode is split into a QBUS Control Stream (managing host communication and logical operations) and a Drive Control Stream (managing interactions with the disk drives).

Key specifications include 67.9 Watts nominal power consumption, 238.6 Btu/hour heat dissipation, and specific environmental requirements. It mounts in two quad-height QBUS SPC slots.

The guide provides detailed installation procedures, covering module placement, I/O page address switch settings (default 172150 octal), and the connection of intermodule, internal, and external SDI cables using standard or alternate bulkhead assemblies.

It outlines field acceptance test procedures, which include running resident diagnostics (indicated by cycling LED patterns on the modules), disk drive diagnostics, and host-resident subsystem diagnostics for PDP-11 and VAX systems. A table of LED error codes is provided for troubleshooting.

Finally, the document discusses system and software considerations, such as enabling error logging, understanding drive numbering (unit numbers 0-254, but potentially OS-limited), and QBUS tuning guidelines for optimizing system performance, including device positioning and burst rate parameters.

In essence, this user guide provides comprehensive technical information for the installation, configuration, testing, and operational integration of the KDA50-Q Disk Controller within a Digital Equipment Corporation QBUS-based system.