The ULTRIX Operating System, Version 4.5

This document, "The ULTRIX Operating System, Version 4.5," provides a comprehensive description of Digital Equipment Corporation's native implementation of the UNIX® Operating System. It details the system's features, enhancements, hardware requirements, and compatibility with various systems and standards.

Key aspects covered include:

• Operating System Description: ULTRIX 4.5 is an interactive, demand-paged, virtual memory, multi-processor, time-sharing operating system with a hierarchical file system, disk quotas, and portability across supported Digital systems. It enhances Berkeley 4BSD functionality with features like a configurable file system buffer cache and I/O performance enhancements.
• File System: Supports named directories and sub-directories, with the Digital Generic File System Interface (GFSI) allowing mounting of multiple local and remote file systems, including NFS. It offers POSIX-compliant file and record locking and supports synchronous file system writes for deterministic operations.
• Virtual Memory: Based on 4.2BSD with 4.3BSD performance enhancements and System V memory extensions, supporting demand paging for local and remote files.
• Multiprocessor Support: Enhanced to support multiple processors executing kernel code on both RISC and VAX multiprocessor systems, using semaphores and spin locks for synchronization.
• Specific Features: Highlights include OPEN SCSI CAM for RISC systems, system administration enhancements (like a Graphical User Account Manager), security features compliant with C2 security level, Kerberos authentication, data encryption/decryption options, asynchronous and synchronous line support, and various network protocol support (TCP/IP, Ethernet, NFS, etc.).
• Program Development: Includes compilers like MIPS-ANSI C 3.0 for RISC and VAX C/ULTRIX for VAX systems, along with other development tools.
• Compatibility: Details compatibility with 4BSD, SVID, and POSIX standards, including specific commands and utilities.
• Internationalization: Offers support for library routines, commands, and utilities for developing internationalized software, including Native Language System (NLS) support and tools for message cataloging.
• Hardware Requirements and Support: Lists extensive lists of supported processors, disk drives, magnetic tapes, communication devices, modems, and terminals across various DEC systems (DECstation, DECsystem, MicroVAX, VAXserver, VAX). It also outlines minimum memory configurations and specific hardware considerations.
• Packaging and Licensing: Describes supported and unsupported subsets, optional encryption software, prerequisite software, installation options, and software licensing details, including License Management Facility (LMF) and license options.
• Documentation and Warranty: Outlines the documentation kits available and the software warranty provided by Digital.

The document emphasizes that ULTRIX 4.5 is a mature and feature-rich operating system designed to run on a wide range of Digital hardware platforms, offering robust networking, security, and development capabilities.