MS11-M MOS Memory User Guide

This document is a user guide for the Digital Equipment Corporation (DEC) MS11-M MOS memory module, designed for use with PDP-11 Unibus or Extended Unibus systems. Published in May 1979, it details the module's characteristics, specifications, installation, and programming.

Key aspects covered include:

• Memory Type and Capacity: The MS11-M is a metal oxide semiconductor (MOS), random access memory (RAM) module (M8722). It comes in two versions: MS11-MA (64K x 16-bit words) and MS11-MB (128K x 16-bit words).
• Error Correction Code (ECC): A core feature, the ECC logic detects single-bit and double-bit errors, automatically correcting single-bit data errors to enhance reliability. Double-bit errors are detected but not corrected.
• Configuration: The guide provides instructions for setting the memory's starting address (at 64K boundaries within either 128K Unibus or 2048K Extended Unibus address space) using switches. It also explains how to configure the module for interleaved or noninterleaved operation with other memory modules of the same capacity.
• Control and Status Register (CSR): The document details the CSR, which allows program control of ECC functions, stores diagnostic information, and reports errors.
• Power and Volatility: The memory is volatile (data is lost without power) but supports an optional battery backup unit to retain data during AC power failures by continuously refreshing the MOS storage array.
• Installation Procedures: Covers switch and jumper configurations, backplane placement for different PDP-11 systems, power voltage checks, and the use of the MAINDEC-11-CZMSD diagnostic program for verifying operation.