MS11-E J MOS Memory Maintenance Manual

This document is the MS11-E-J MOS Memory Maintenance Manual, published by Digital Equipment Corporation in October 1975 for their PDP-11 Unibus computer systems.

It serves as a comprehensive guide for technicians on the installation, operation, and troubleshooting of the MS11 series of MOS (Metal-Oxide-Semiconductor) random-access memory modules.

Key aspects covered include:

• Introduction to MS11 Memory: Describes the MS11 as a group of dynamic MOS semiconductor memories (4K to 16K words, 16 or 18 bits) designed as slave devices for the PDP-11 Unibus. It highlights advantages like low cost, non-destructive readouts, and lower power consumption compared to core memory, while also addressing the volatility of MOS memory (requiring battery-supported power supplies) and the necessity of periodic data refreshing.
• Installation Procedures: Details steps such as verifying factory-installed jumpers, arranging switches for Unibus address assignment, checking DC voltages, installing the module in the backplane, and performing a diagnostic check.
• Chip and Logic Description: Provides in-depth technical details of the 4096-bit MOS memory chip, including its physical layout, operation (row/column address latching, refresh mechanism), and timing. It then extensively describes the module's internal logic, including address decoding, timing signal generation for bus and refresh cycles, refresh logic, address path logic, and data path logic.
• Troubleshooting Hints: Offers practical advice for diagnosing problems, categorized into issues preventing diagnostic program loading (e.g., BUS SSYN L not asserted) and those occurring during diagnostic execution. It provides specific checks for refresh circuits, data circuits, address circuits, write logic, and loader memory space, including methods to isolate faulty memory banks.
• Appendices: Includes reference information such as MS11 switch settings for various address assignments and I/O page operations, along with descriptions of key integrated circuits used in the MS11 logic.

In essence, the manual provides the necessary technical information and practical guidance for understanding, installing, and maintaining the MS11-E-J MOS memory modules in a PDP-11 system.