The Fuzzball

This document describes the Fuzzball, a compact, fast operating system and applications library designed for PDP-11 computers, which served as a development platform for the DARPA/NSF Internet. The paper outlines the Fuzzball's system architecture, including its process and memory structure, interprocess communication, and emulator features for running RT-11 software. Additionally, it highlights the Fuzzball's critical role in experiments regarding internetwork performance—specifically in congestion control, preemption strategies, and time synchronization via the Network Time Protocol (NTP).