MSV11-J MOS Memory User's Guide

This document is a User's Guide for the Digital Equipment Corporation MSV11-J MOS Memory module, first published in May 1985.

Key Information:

1. Purpose: It describes the MSV11-J, a metal oxide semiconductor (MOS) random access memory (RAM) module, its features, operation, configuration, and diagnostic procedures.
2. Core Functionality: The MSV11-J provides memory with Error Detection and Correction (ECC) capabilities, designed to detect and correct single-bit errors and detect double-bit errors, enhancing reliability. This correction is transparent to the master device.
3. Capacity & Compatibility:
   • Offers up to 2 Megabytes (Mb) of memory using 256K dynamic RAMs, configurable as half or fully populated.
   • Designed for Q-bus systems (specifically PDP-11/83 and PDP-11/84 UNIBUS systems via an adapter).
   • Supports both the standard Q-bus protocol (for MSV11-JD and MSV11-JE variations) and a faster Private Memory Interconnect (PMI) protocol used by the KDJ11-B processor.
   • Critical Warning: It is compatible with Q-CD backplanes but not with Q-Q backplanes, as insertion into the latter can cause damage.
4. Features:
   • Configurable battery backup for data retention during power loss.
   • On-board RAM refresh that is transparent to the CPU.
   • A Control and Status Register (CSR) for programmatic control of ECC functions, diagnostics, and error reporting. The CSR can be assigned one of 16 addresses.
   • LED indicators for power (+5V/VBB) and uncorrectable errors.
   • Uses gate arrays (VLSI technology) and advanced Schottky TTL logic.
5. Operation: The guide details how data flows during various memory cycles (read, write, write byte, block mode, read-modify-write) and describes the internal ECC Initialization cycle that occurs on power-up.
6. Configuration: It provides instructions for module installation, including setting jumpers (for RAM population and battery backup) and switches (for defining starting memory addresses and CSR addresses).
7. Diagnostics & Maintenance:
   • No general preventive maintenance is required for the module itself, beyond general system checks.
   • Describes the CVMJA0 standalone diagnostic program used to test ECC and memory integrity, including how to control its behavior via software switch settings.
   • Lists Digital's repair and support services, including contact information for various regions.