computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied science, practical discipli ...

, a single address space operating system (or SASOS) is an

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...

that provides only one globally shared address space for all processes. In a single address space operating system, numerically identical (

virtual memory In computing, virtual memory, or virtual storage is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very l ...

)

logical address In computing, a logical address is the address at which an item ( memory cell, storage element, network host) appears to reside from the perspective of an executing application program. A logical address may be different from the physical addr ...

es in different processes all refer to exactly the same byte of data. Single address-space operating systems offer certain advantages. In a traditional OS with private per-process address space, memory protection is based on address space boundaries ("address space isolation"). Single address-space operating systems use a different approach for memory protection that is just as strong. One advantage is that the same virtual-to-physical map

page table A page table is the data structure used by a virtual memory system in a computer operating system to store the mapping between virtual addresses and physical addresses. Virtual addresses are used by the program executed by the accessing process, ...

can be used with every process (and in some SASOS, the kernel as well). This makes context switches on a SASOS faster than on operating systems that must change the page table and flush the TLB caches on every context switch. SASOS projects include the following: * Amiga family –

AmigaOS AmigaOS is a family of proprietary native operating systems of the Amiga and AmigaOne personal computers. It was developed first by Commodore International and introduced with the launch of the first Amiga, the Amiga 1000, in 1985. Early version ...

AROS Aros may refer to: *Aros (Middle-earth), a river in J. R. R. Tolkien's Middle-earth legendarium * Aros, Mull, the location of Aros Castle, a ruined 13th-century castle on the Isle of Mull, Scotland *AROS Research Operating System, a free software i ...

and

MorphOS MorphOS is an AmigaOS-like computer operating system (OS). It is a mixed proprietary and open source OS produced for the Pegasos PowerPC (PPC) processor based computer, PowerUP accelerator equipped Amiga computers, and a series of Freescale dev ...

Angel
*

BareMetal BareMetal is an exokernel-based single address space operating system (OS) created by Return Infinity. It is written in assembly to achieve high-performance computing with minimal footprint with a "just enough operating system" ( JeOS) approac ...

Br1X
*

Genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

by Symbolics * IBM i (formerly called OS/400)
Iguana
at

NICTA NICTA (formerly named National ICT Australia Ltd) was Australia's Information and Communications Technology (ICT) Research Centre of Excellence and is now known as CSIRO's Data61. The term "Centre of Excellence" is common marketing terminology u ...

, Australia * JX a research Java OS *

IncludeOS IncludeOS is a minimal, open source, unikernel operating system for cloud services and IoT. IncludeOS allows users to run C++ applications in the cloud without any operating system. IncludeOS adds operating system functionality to an application ...

Mungi
at

, Australia
Nemesis

*

OS-9 OS-9 is a family of real-time, process-based, multitasking, multi-user operating systems, developed in the 1980s, originally by Microware Systems Corporation for the Motorola 6809 microprocessor. It was purchased by Radisys Corp in 2001, an ...

Phantom OS Phantom OS is an operating system (OS) made by mostly Russian programmers (with help of some Uzbeks). It is based on a concept of persistent virtual memory, and uses a virtual machine, managed code, and bytecodes. It is one of a few OSes not bas ...

* Scout * Singularity
Sombrero
*

TempleOS TempleOS (formerly J Operating System, LoseThos, and SparrowOS) is a biblical-themed lightweight operating system (OS) designed to be the Third Temple prophesied in the Bible. It was created by American programmer Terry A. Davis, who develope ...

Theseus OS

Torsion
*

VxWorks VxWorks is a real-time operating system (or RTOS) developed as proprietary software by Wind River Systems, a wholly-owned subsidiary of Aptiv. First released in 1987, VxWorks is designed for use in embedded systems requiring real-time, determi ...

"Vxworks Tutorial"
quote: "In vxworks ... all application tasks share the same address space nless theoptional tool named VxVMI

as been As, AS, A. S., A/S or similar may refer to: Art, entertainment, and media * A. S. Byatt (born 1936), English critic, novelist, poet and short story writer * "As" (song), by Stevie Wonder * , a Spanish sports newspaper * , an academic male voic ...

used to allow each task to have its own address space." *

Zephyr In European tradition, a zephyr is a light wind or a west wind, named after Zephyrus, the Greek god or personification of the west wind. Zephyr may also refer to: Arts and media Fiction Fiction media * ''Zephyr'' (film), a 2010 Turkish ...

References

Bibliography

* . * * * Operating systems {{comp-eng-stub

See also

References

Bibliography