KT11-D Memory Management Option User's Manual

This document is a user's manual for the KT11-D Memory Management Unit (MMU) option for the Digital Equipment Corporation (DEC) PDP-11 Programmed Data Processor.

The manual details how the KT11-D enhances the PDP-11 system by:

• Memory Expansion: Extending the basic 32K-word address capability to 128K words.
• Virtual Addressing and Relocation: Providing a "virtual" address space with automatic memory relocation, allowing programs to appear as if they start at address 0 regardless of their physical location.
• Memory Protection: Implementing robust memory protection features for multi-user, multi-program systems, including separate Kernel/User operating modes, read-only pages, and inaccessible memory zones to prevent unauthorized access and modification.
• Dynamic Memory Allocation: Enabling flexible allocation of memory in small (as little as 32 words) or large (up to 4K-word pages) blocks, minimizing fragmentation and supporting features like dynamic array construction.
• Memory Management Statistics: Providing hardware-maintained flags (like the "W-bit") to aid operating systems in efficient memory swapping.

The document describes the hardware's function, including how 16-bit virtual addresses are converted to 18-bit physical addresses using Page Address Registers (PAR) and Page Descriptor Registers (PDR). It also covers specific memory management instructions (MTPI, MFPI) for inter-mode communication and explains the use of status registers (SR0, SR2) for monitoring and fault recovery.

Aimed at system programmers developing operating system memory management modules and maintenance personnel, the manual provides an overall understanding of the KT11-D's operation, programming considerations, and installation procedures.