IBM i Release History
From OS/400 V1R1 in 1988 through IBM i 7.5 today, the IBM i version lineage spans nearly four decades under three different names. This is the release timeline, from the original AS400 operating system to the current version.
The operating system now called IBM i has been in continuous, backward-compatible development since 1988, spanning three separate OS brand names, OS/400, i5/OS, and IBM i, across four hardware brand eras: AS400, iSeries, System i, and IBM Power Systems. The version timeline below traces that lineage.
OS/400 Era (1988-2004)
IBM shipped OS/400 V1R1 with the original AS/400 in 1988. Through the 1990s and early 2000s, IBM released annual and biennial updates under the V1Rx through V4Rx naming convention, adding capability while preserving application compatibility across releases. This era covers both the original AS400 branding (1988-2000) and the early iSeries branding (2000-2004), with the OS name itself remaining OS/400 throughout. See OS/400 and AS400 model history for more on this period.
i5/OS Era (2004-2008)
IBM renamed OS/400 to i5/OS with the V5R3 release in 2004, aligning the OS name with the iSeries i5 hardware refresh onto POWER5 processors that same year. i5/OS continued through the System i hardware branding period (2006-2008) as V5R4 and into IBM i 6.1. See iSeries model history and System i model history for the corresponding hardware timeline.
IBM i Era (2008-Present)
| Release | General availability |
|---|---|
| IBM i 6.1 | 2008 |
| IBM i 7.1 | 2010 |
| IBM i 7.2 | 2014 |
| IBM i 7.3 | 2016 |
| IBM i 7.4 | 2019 |
| IBM i 7.5 | 2022 |
IBM i 6.1, released in 2008, was the first version under the current IBM i name, coinciding with the split of the OS brand from the hardware brand (which became IBM Power Systems). IBM i 7.5, released in 2022, is the current release.
Why the Version History Matters
The long, unbroken compatibility chain from OS/400 V1R1 through IBM i 7.5 is precisely why applications written in the 1990s can still run on current Power11 hardware. It is also why organizations describing their environment as "AS400" and organizations describing it as "IBM i 7.4" may be running functionally similar workloads separated only by which era's terminology they use. See IBM i support status for which of these releases are still actively supported today.