View source for Advanced Comprehensive Operating System

{{Short description|Family of mainframe computer operating systems developed by NEC for the Japanese market}}
{{third-party|date=June 2011}}
{{Infobox OS
| name                   = Advanced Comprehensive Operating System (ACOS)<!-- Name of program or distribution -->
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| developer              = [[NEC]]<!-- Name of main developer or sponsor-->
| family                 = [[General Comprehensive Operating System]]<!-- "Unix-like" or "Microsoft Windows" -->
| working state          = Current<!-- "Current", "Discontinued" (operating systems), or "No longer supported" (releases) -->
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| website                = {{URL|jpn.nec.com/products/acosclub/}}
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'''Advanced Comprehensive Operating System''' ('''ACOS''') is a family of [[mainframe computer]] [[operating system]]s developed by [[NEC]] for the Japanese market. It consists of three systems, based on the [[General Comprehensive Operating System]] family developed by [[General Electric]], [[Honeywell]], and [[Groupe Bull|Bull]]. Two of these systems, '''ACOS-2''' (based on GCOS 4) and '''ACOS-4''' (based on GCOS 7) are still sold, although only ACOS-4 is under active development. '''ACOS-6''' (based on GCOS 8) is an obsolete high-end mainframe platform, which ceased active development in the early 2000s.

The first two models in NEC's [[NEC SX|SX series of supercomputers]], the SX-1 and the SX-2 (released in 1985), ran an operating system derived from ACOS-4, which was variously called either SX-OS or SXCP (SX System Control Program).<ref>{{Cite journal|last=Oyanagi|first=Yoshio|date=December 1999|title=Development of supercomputers in Japan: Hardware and software|journal=Parallel Computing|language=en|volume=25|issue=13–14|pages=1545–1567|doi=10.1016/S0167-8191(99)00084-8}}</ref><ref>{{Cite web|url=https://dl.acm.org/doi/abs/10.5555/324493.325033|title=Fortran and tuning utilities aiming at ease of use of a supercomputer {{!}} Proceedings of 1986 ACM Fall joint computer conference|last1=Katayama|first1=Hiroshi|last2=Tsukagoshi|first2=Makoto|date=November 1986|website=dl.acm.org|language=EN|archive-url=|archive-date=|access-date=2020-04-09}}</ref><ref>{{Cite web|url=https://www.itfind.or.kr/Report/200301/ETRI/ETRI-0464/ETRI-0464.pdf|title=A Feasibility Study of Supercomputer Installation in ETRI.|last=|first=|date=1987|website=ETRI|page=134|language=ko|archive-url=|archive-date=|access-date=}}</ref> However, subsequent SX supercomputers, starting with the SX-3 (released in 1990), instead ran a derivative of Unix.

In late September 2012, NEC announced a return from [[IA-64]] to the previous NOAH line of proprietary mainframe processors for ACOS-4, now produced in a quad-core variant on 40 nm, called NOAH-6.<ref>[http://www.nec.co.jp/products/acosclub/kataru/03/01.html With the new CPU NOAH - 6, the next generation platform i - PX 9800 was born]</ref>
ACOS-2 runs on [[Intel]] [[Xeon]] servers.

In June 2022, i-PX AKATSUKI server equipped with NEC's original processor (NOAH-7) was released.

==See also==
* [[Timeline of operating systems]]

==References==
{{Reflist}}

==External links==
* [https://jpn.nec.com/products/acosclub/ ACOS Club home page]
* [https://web.archive.org/web/20100709213845/http://www.feb-patrimoine.com/english/gecos_to_gcos8_part_1.htm A history of GE/Honeywell/NEC/Bull operating systems]

{{Operating system}}

[[Category:Proprietary operating systems]]
[[Category:Computing platforms]]
[[Category:NEC software]]
[[Category:Mainframe computers]]
[[Category:Mainframe computer software]]
{{Mainframe-compu-stub}}