A Journey of Modern OS Construction From boot to DOOM

VOS is a first-of-its-kind instructional OS that: (1) Runs on commodity, portable hardware. (2) Showcases modern features, including per-app address spaces, threading, commodity filesystems, USB, DMA, multicore, self-hosted debugging, and a window manager. (3) Supports rich applications such as 2D/3D games, music and video players, and a blockchain miner. Unlike traditional instructional systems, VOS emphasizes strong motivation for building systems-supporting engaging, media-rich apps that go beyond basic terminal programs. To achieve this, we design VOS to strike a careful balance between essential OS complexity and overall simplicity. Our method, which we call inverse engineering, breaks down a full-featured OS into a set of incremental, self-contained prototypes. Each prototype introduces a minimal set of OS mechanisms, driven by the needs of specific apps. The construction process (i.e., forward engineering) then progressively enables these apps by bringing up one mechanism at a time. VOS makes it accessible for a wider audience to experience building a software system that is self-contained and usable in everyday scenarios.