M9301 Bootstrap Terminator Maintenance Manual

This document is the preliminary maintenance manual for the Digital Equipment Corporation (DEC) M9301 Bootstrap Terminator module, designed for PDP-11 computers.

The M9301 is a double-height extended module that combines UNIBUS termination resistors with a 512-word Read-Only Memory (ROM) to store and initiate bootstrap programs.

Key features and functionalities include:

• Bootstrap Initiation: Programs can be initiated on power-up (optionally enabled/disabled), via an external boot switch, direct program jumps, or console commands. On power-up, it can force the processor to read its initial Program Counter (PC) and Program Status Word (PSW) from its internal ROM.
• ROM Storage: The 512-word ROM contains various bootstrap routines and diagnostics, accessible within specific UNIBUS address spaces. An address offset switch bank allows selection of different routines.
• Physical and Electrical Specifications: Details power consumption, UNIBUS interface, and external electrical interfaces (TP1, TP2, TP3) with their loading and usage constraints.
• Hardware Description: Explains the logic behind power-up booting, power-up clear, address detection, and the ROM memory structure.
• Variations: The manual describes multiple M9301 versions (-0, -YA, -YB, -YC, -YD), each tailored with different features such as user-programmable ROMs, various DEC-standard bootstrap programs for peripherals (e.g., diskettes, tapes), CPU and memory diagnostics, and specific applications like DDCMP (Digital Data Communications Message Protocol) support.
• Console Emulator: A significant portion is dedicated to the Console Emulator routine, which allows users to perform operations like loading addresses, examining memory contents, depositing data, starting programs, and booting devices via keyboard input, including detailed flowcharts and error handling.
• Extended Addressing: It covers how the module interacts with extended addressing schemes, defining virtual and physical addresses, address mapping with and without memory management, and the use of associated registers.
• Maintenance Information: Provides technical requirements, programming constraints for the ROM, and details about the module's physical construction and environmental specifications.

In essence, the M9301 module serves as a crucial component for PDP-11 systems, offering integrated bus termination, versatile bootstrap capabilities, and diagnostic tools, with specific variants optimized for different hardware configurations and user requirements.