View source for OS/400

{{Infobox Software
| title = OS/400
| image = S36 SSP.png
| intro = xx, 1988
| discon = Current
| isa = [[IMPI]], [[PowerPC AS]]
}}

'''OS/400''' is the operating system of the [[AS/400]]. It is an evolution of the earlier [[Control Program Facility]] found on the [[System/38]] and, although the OS/400 branding has been dropped, is still maintained and developed by IBM.

== Notable Versions ==
V2R2 is believed to be the first version of OS/400 to introduce the [[System Password]] mechanism.

V3R1 is the first version of OS/400 to add TCP/IP support. It is also one of two versions of OS/400 to receive a simultaneous IPMI and PowerPC AS release; its contemporary PowerPC version was V3R5.

V4R4 is the preferred version of OS/400 to run on first-generation PowerPC AS machines as it is far less demanding on system resources when compared to V5R1, and is the final version of OS/400 to support [[Advanced/36]] and [[OfficeVision]].

V4R5 drops all support for Advanced/36 and OfficeVision, and these applications will be removed when upgrading to V4R5. It is also the final version of OS/400 to not require license keys when installed on an [[AS/400 Model 150]].

V5R1, like its later V5R4 counterpart, was one of the long-toothed releases of OS/400 and could still be found driving many businesses into the 2010s. It is also the final version to be branded OS/400.

== Archived Versions ==
[[OS/400 V3R1]]

[[OS/400 V4R4]]

[[OS/400 V5R1]]

[[Category:Software]] [[Category:Operating Systems]]