ARX was an unreleased Mach-like

operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...

written in

Modula-2+ Modula-2+ is a programming language descended from the Modula-2 language. It was developed at DEC Systems Research Center (SRC) and Acorn Computers Ltd Research Centre in Palo Alto, California. Modula-2+ is Modula-2 with exceptions and threads. ...

developed by

Acorn Computers Acorn Computers Ltd. was a British computer company established in Cambridge, England in 1978 by Hermann Hauser, Christopher Curry (businessman), Chris Curry and Andy Hopper. The company produced a number of computers during the 1980s with asso ...

Ltd in the Acorn Research Centre (ARC)

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

(UK) and later by

Olivetti Olivetti S.p.A. is an Italian manufacturer of computers, tablets, smartphones, printers and other such business products as calculators and fax machines. Headquartered in Ivrea, in the Metropolitan City of Turin, the company has been owned b ...

—which purchased Acorn—for Acorn's new

Archimedes Archimedes of Syracuse ( ; ) was an Ancient Greece, Ancient Greek Greek mathematics, mathematician, physicist, engineer, astronomer, and Invention, inventor from the ancient city of Syracuse, Sicily, Syracuse in History of Greek and Hellenis ...

personal computers based on the

ARM architecture ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computer, RISC instruction set architectures (ISAs) for central processing unit, com ...

reduced instruction set computer In electronics and computer science, a reduced instruction set computer (RISC) is a computer architecture designed to simplify the individual instructions given to the computer to accomplish tasks. Compared to the instructions given to a com ...

(RISC)

central processing unit A central processing unit (CPU), also called a central processor, main processor, or just processor, is the primary Processor (computing), processor in a given computer. Its electronic circuitry executes Instruction (computing), instructions ...

(CPUs).

Overview

According to the project Application ManagerTOP3 smart moves
Richard Cownie. Real World Technologies (September 2009) Richard Cownie, during the project, while Acorn was developing the kernel, it used the C and Acorn Modula Execution Library (CAMEL) in the Acorn Extended Modula-2 (AEM2) compiler (ported from

Modula-2 Modula-2 is a structured, procedural programming language developed between 1977 and 1985/8 by Niklaus Wirth at ETH Zurich. It was created as the language for the operating system and application software of the Lilith personal workstation. It w ...

ETH Zurich ETH Zurich (; ) is a public university in Zurich, Switzerland. Founded in 1854 with the stated mission to educate engineers and scientists, the university focuses primarily on science, technology, engineering, and mathematics. ETH Zurich ran ...

(ETH) using

Econet Econet was Acorn Computers's low-cost local area network system, based on a Carrier-sense multiple access with collision detection, CSMA-CD serial protocol carried over a five-wire Bus (computing), data bus, intended for use by schools and sm ...

hardware). Though never released externally, CAMEL was ported to use on

Sun Microsystems Sun Microsystems, Inc., often known as Sun for short, was an American technology company that existed from 1982 to 2010 which developed and sold computers, computer components, software, and information technology services. Sun contributed sig ...

Unix computers. In an effort to port Sun's

workstation A workstation is a special computer designed for technical or computational science, scientific applications. Intended primarily to be used by a single user, they are commonly connected to a local area network and run multi-user operating syste ...

s Sun

NeWS News is information about current events. This may be provided through many different Media (communication), media: word of mouth, printing, Mail, postal systems, broadcasting, Telecommunications, electronic communication, or through the te ...

to the Archimedes, David Chase developed a compiler based on AEM2 for the programming language

Modula-3 Modula-3 is a programming language conceived as a successor to an upgraded version of Modula-2 known as Modula-2+. It has been influential in research circles (influencing the designs of languages such as Java, C#, Python and Nim), but it ha ...

. ARX was a preemptive multitasking, multithreading, multi-user

. Much of the OS ran in

user mode A modern computer operating system usually uses virtual memory to provide separate address spaces or regions of a single address space, called user space and kernel space. This separation primarily provides memory protection and hardware prote ...

and as a result suffered performance problems due to switches into

kernel mode In computer science, hierarchical protection domains, often called protection rings, are mechanisms to protect data and functionality from faults (by improving fault tolerance) and malicious behavior (by providing computer security). Computer ...

to perform mutexes, which led to the introduction of the SWP instruction to the instruction set of the ARMv2a version of the ARM processor. It had support of a file system for optical (

write once read many Write once read many (WORM) describes a data storage device in which information, once written, cannot be modified. This write protection affords the assurance that the data cannot be tampered with once it is written to the device, excluding the ...

(WORM)) disks and featured a window system, a window toolkit (and a direct manipulation

user interface In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine fro ...

(UI) editor) and an Interscript-based text editor, for enriched documents written in Interpress (a

HTML Hypertext Markup Language (HTML) is the standard markup language for documents designed to be displayed in a web browser. It defines the content and structure of web content. It is often assisted by technologies such as Cascading Style Sheets ( ...

precursor). The OS had to be fitted in a 512 KB

read-only memory Read-only memory (ROM) is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM cannot be electronically modified after the manufacture of the memory device. Read-only memory is useful for storing sof ...

(ROM)

ROM image A ROM image, or ROM file, is a computer file which contains a copy of the data from a read-only memory Computer chip, chip, often from a ROM cartridge, video game cartridge, or used to contain a computer's firmware, or from an arcade game's arc ...

. This suggests that ARX had a

microkernel In computer science, a microkernel (often abbreviated as μ-kernel) is the near-minimum amount of software that can provide the mechanisms needed to implement an operating system (OS). These mechanisms include low-level address space management, ...

-type design. It was not finished in time to be used in the Acorn Archimedes range of computers, which shipped in 1987 with an operating system named Arthur, later renamed

RISC OS RISC OS () is an operating system designed to run on ARM architecture, ARM computers. Originally designed in 1987 by Acorn Computers of England, it was made for use in its new line of ARM-based Acorn Archimedes, Archimedes personal computers an ...

, derived from the earlier Machine Operating System (MOS) from Acorn's earlier

8-bit In computer architecture, 8-bit integers or other data units are those that are 8 bits wide (1 octet). Also, 8-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers or data bu ...

BBC Micro The BBC Microcomputer System, or BBC Micro, is a family of microcomputers developed and manufactured by Acorn Computers in the early 1980s as part of the BBC's Computer Literacy Project. Launched in December 1981, it was showcased across severa ...

range. A set of Usenet posts detailing why ARX was abandoned for RISC OS. Confusion persisted about the nature of ARX amongst the wider public and press, with some believing that ARX was Acorn's own Unix variant, with this view being refined in time to accommodate ARX as Acorn's own attempt to deliver a "UNIX look-alike" whose development had been abandoned in favour of a traditional Unix version for the Archimedes, which ultimately emerged as

RISC iX RISC iX is a discontinued Unix operating system designed to run on a series of workstations based on the Acorn Archimedes microcomputer. Heavily based on 4.3BSD, it was initially completed in 1988, a year after Arthur but before RISC OS. It was ...

. The Acorn Research Centre was acquired by

References

External links

ARX features

History of the addition of the SWP instruction to the ARM3 instruction set
{{DEFAULTSORT:Arx (operating system) Acorn Computers operating systems ARM operating systems Discontinued operating systems Microkernel-based operating systems Microkernels

Overview

See also

References

External links