Editing IBM AS/400 (section)

{{Short description|IBM midrange computer (1988–2013)}}
{{Infobox Computer
| name   = IBM AS/400
| logo   = IBM AS400 wordmark.svg
| aka    = AS/400e, eServer iSeries, eServer i5, System i
| type   = [[Midrange computer]]
| os     = [[OS/400]] (later known as i5/OS and IBM i)
| cpu    = {{Plain list|
* IMPI
* [[IBM RS64]]
* [[IBM Power microprocessors|POWER]]
}}
| image  =
| caption      = IBM AS/400e model 730
| predecessor  = [[IBM System/38]],{{Clear}}[[IBM System/36]]
| successor    = [[IBM Power Systems]] running [[IBM i]]
| manufacturer = IBM
| discontinued = Sep 30, 2013
| release date = June 1988 (Announced)<br />August 1988 (Release)
| related      = [[IBM System p]]
| website      = {{web archive|url=https://web.archive.org/web/20000302140252/http://www.as400.ibm.com/|title=as400.ibm.com}}
}}
The '''IBM AS/400''' ('''Application System/400''') is a family of [[midrange computer]]s from [[IBM]] announced in June 1988 and released in August 1988. It was the successor to the [[System/36]] and [[System/38]] platforms, and ran the [[OS/400]] operating system. Lower-cost but more powerful than its predecessors, an estimated 111,000 installations existed by the end of 1990 and annual revenue reaching $14 billion that year,<ref>{{cite magazine |magazine=Computerworld |date= 29 April 1991 |first=Teresa |last=Elms |title=Side road to success |page=27 |url=https://books.google.com/books?id=IvFeiX1fIzgC&pg=PA27}}</ref> increasing to 250,000 systems by 1994,<ref>{{cite magazine |magazine= InfoWorld |date= 14 February 1994 |first=Paul |last=Korzenioski |title=AS/400 in the LAN environment |page=52 |url=https://books.google.com/books?id=7DoEAAAAMBAJ&pg=PA52}}</ref> and about 500,000 shipped by 1997.<ref>{{cite web |last1=IBM |title=IBM AS/400 |url=https://www.ibm.com/ibm/history/exhibits/rochester/rochester_4010.html |website=IBM.com |date=23 January 2003 |publisher=International Business Machines Corporation |access-date=20 March 2022}}</ref>

A key concept in the AS/400 platform is [[IBM i#TIMI|Technology Independent Machine Interface]]{{efn|Upward compatible from the [[IBM System/38# Machine Interface|Machine Interface (MI)]] of the [[IBM System/38|S/38]]}} (TIMI), a platform-independent [[instruction set architecture]] (ISA) that is translated to native [[machine language]] instructions. The platform has used this capability to change the underlying processor architecture without breaking application compatibility. Early systems were based on a 48-bit [[Complex instruction set computer|CISC]] instruction set architecture known as the ''Internal Microprogrammed Interface'' (IMPI), originally developed for the System/38.<ref>{{cite web|url=http://users.snip.net/~gbooker/AS400/arch.htm|title=Notes for storage research|author=David McKenzie|archive-url=https://web.archive.org/web/19991008185025/http://users.snip.net/~gbooker/AS400/arch.htm|archive-date=October 8, 1999|url-status=dead}}</ref> In 1991, the company introduced a new version of the system running on a series of [[64-bit computing|64-bit]] [[PowerPC]]-derived CPUs, the [[IBM RS64]] family.<ref name="Soltis PowerPC">{{cite web | author=Soltis, Frank G. | title=When Is PowerPC Not PowerPC? | work=The 400 Squadron | url=http://www.the400squadron.com/amug/200406/NotPowerPC.htm | archive-url=https://web.archive.org/web/20080108195918/http://www.the400squadron.com/amug/200406/NotPowerPC.htm | archive-date=January 8, 2008 | url-status=dead }}</ref> Due to the use of TIMI, applications for the original CISC-based programs continued to run on the new systems without modification, as the TIMI code can be re-translated to the new systems' PowerPC [[Power ISA]] native machine code. The RS64 was replaced with [[POWER4]] processors in 2001, which was followed by [[POWER5]] and [[POWER6]] in later upgrades.

The AS/400 went through multiple re-branding exercises, finally becoming the '''System i''' in 2006. In 2008, IBM consolidated the separate System i and [[System p]] product lines (which had mostly identical hardware by that point)<ref name="system-p-i">{{cite web|url=https://www.itjungle.com/2008/03/17/tfh031708-story01/|title=Bye Bye System p and i, Hello Power Systems|date=2008-04-07|author=Timothy Prickett-Morgan|access-date=2021-10-09|website=IT Jungle}}</ref> into a single product line named [[IBM Power Systems]].<ref name="Niccolai">{{cite web|title=IBM merges System i and System p server lines|url=https://www.infoworld.com/article/2649318/ibm-merges-system-i-and-system-p-server-lines.html|last=Niccolai|first=James|date=April 2, 2008|website=[[InfoWorld]]|url-access=limited}}</ref><ref>{{cite web|url=https://www.itjungle.com/2008/04/07/tfh040708-story01/|title=It's Official: Now We're Power Systems and i for Business|author=Timothy Prickett Morgan|date=2008-04-07|access-date=2021-03-15|website=itjungle.com}}</ref> The name "AS/400" is sometimes used informally to refer to the [[IBM i]] operating system running on modern Power Systems hardware.<ref>{{cite web|url=https://www.itjungle.com/2017/07/17/course-not-as400/|title=Of Course i's Not The AS/400|author=Alex Woodie|website=IT Jungle|date=2017-07-17|access-date=2021-11-22}}</ref>