Editing Amoeba (operating system) (section)

==Overview==
The goal of the Amoeba project was to construct an operating system for networks of computers that would present the network to the user as if it were a single machine. An Amoeba network consists of a number of [[workstation]]s connected to a "pool" of processors, and executing a program from a terminal causes it to run on any of the available processors, with the operating system providing [[load balancing (computing)|load balancing]].<ref name="statusreport"/> Unlike the contemporary [[Sprite (operating system)|Sprite]], Amoeba does not support [[process migration]].<ref>Fred Douglis, [[M. Frans Kaashoek]], Andrew S. Tanenbaum and [[John K. Ousterhout|John Ousterhout]] (1991). [http://pdos.csail.mit.edu/~kaashoek/papers/amsp.ps A comparison of two distributed systems: Amoeba and Sprite]. Computing Systems '''4'''(4), pp. 353–384.</ref>
The workstations would typically function as networked [[computer terminal|terminals]] only. Aside from workstations and processors, additional machines operate as [[server (computing)|server]]s for files, directory services, [[TCP/IP]] communications etc.<ref name="statusreport">[[Andrew S. Tanenbaum]], [[M. Frans Kaashoek]], Robbert van Renesse and Henri E. Bal (1991). [http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.35.6888 The Amoeba distributed operating system — a status report]. Computer Communications '''14'''.</ref>

Amoeba is a [[microkernel]]-based operating system. It offers [[multithreading (software)|multithreaded]] programs and a [[remote procedure call]] (RPC) mechanism for communication between threads, potentially across the network; even kernel-threads use this RPC mechanism for communication. Each thread is assigned a 48-bit number called its "port", which serves as its unique, network-wide "address" for communication.<ref name="statusreport"/>

The user interface and [[Application programming interface|APIs]] of Amoeba were modeled after [[Unix]] and compliance with the [[POSIX]] standard was partially implemented; some of the Unix emulation code consists of utilities ported over from Tanenbaum's other operating system, [[MINIX]]. Early versions used a "homebrew" window system, which the Amoeba authors considered "faster ... in our view, cleaner ... smaller and much easier to understand", but version 4.0 uses the [[X Window System]] (and allows [[X terminal]]s as terminals).<ref name="statusreport"/>
The system uses [[Fast Local Internet Protocol|FLIP]] as a network protocol.