PRIMOS

PRIMOS was the proprietary operating system used on the series of Prime Computer minicomputers. Prime Computer, founded in 1972, aimed to provide time-sharing systems for businesses and research institutions. PRIMOS was central to their offering.

Key Features and Characteristics:

• Virtual Memory: PRIMOS was an early adopter of virtual memory management, allowing programs to address more memory than physically available. This was a significant advantage in the minicomputer era.
• Multics Influence: PRIMOS was heavily influenced by the Multics operating system, particularly in its file system organization and its approach to security. Many of the original PRIMOS developers had experience with Multics.
• Ring-based Security: PRIMOS employed a ring-based security model to protect the operating system kernel and user data. This layered approach restricted access to system resources based on privilege level.
• Directory Structure: The PRIMOS file system was hierarchical, similar to Unix, enabling a structured organization of files and directories.
• Command Line Interface (CLI): Users interacted with PRIMOS through a command-line interface. While the command set was distinct from Unix, it offered comparable functionality for file manipulation, program execution, and system administration.
• Programming Languages: PRIMOS supported a variety of programming languages, including FORTRAN, COBOL, Pascal, and PL/I.
• Networking: Later versions of PRIMOS incorporated networking capabilities, including support for protocols such as X.25 and TCP/IP.
• Database Management: Prime Computer also offered database management systems that ran on PRIMOS, contributing to its adoption in business environments.
• Time-Sharing: Designed from the ground up for time-sharing, PRIMOS efficiently managed multiple concurrent users, providing each with a slice of the processor's time.
• Legacy: Although Prime Computer was acquired in the late 1980s, PRIMOS retains a place in computing history as a significant operating system of its era, demonstrating advanced concepts in memory management, security, and time-sharing. It is now largely considered a legacy system.