What is an OS?

TL;DR

This paper offers formal definitions and principles to understand the core structure and purpose of operating systems, aiming to create a symbolic framework that encompasses practical OS design and algorithms.

Contribution

It introduces formal definitions of OS, processes, and files, along with principles that identify core operations and algorithms, providing a foundational framework for OS analysis.

Findings

Definitions of OS, processes, and files established.

Core operations for single computer OS identified.

Framework derived from paging and segmentation algorithms.

Abstract

While the engineering of operating systems is well understood, their formal structure and properties are not. The latter needs a clear definition of the purpose of an OS and an identification of the core. In this paper I offer definitions of the OS, processes and files, and present a few useful principles. The principles allow us to identify work like closure and continuation algorithms, in programming languages that is useful for the OS problem. The definitions and principles should yield a symbolic, albeit semiquantitative, framework that encompasses practice. Towards that end I specialise the definitions to describe conventional OSes and identify the core operations for a single computer OS that can be used to express their algorithms. The assumptions underlying the algorithms offer the design space framework. The paging and segmentation algorithms for conventional OSes are extracted from the framework as a check. Among the insights the emerge is that an OS is a constructive proof of equivalence between models of computation. Clear and useful definitions and principles are the first step towards a fully quantitative structure of an OS.