I5/OS
From Your Next Level of Support
i5/OS is the operating system of the IBM iSeries. It is still OS/400 under the hood, but the branding was changed to coincide with the release of the new (and short-lived) iSeries, pSeries, POWER5, and P5 branding.
Notable Versions
V5R4 is one of the most used releases of i5/OS, still in use in businesses where the latest features are not critical and is still popular amongst those who rely on green screen interfaces.
The entire family of Version 6 is regarded as "the Windows Vista of AS/400" as it contained many under-the-hood changes to the TIMI which broke application compatibility. As a result, many businesses stayed on V5R4 or waited until IBM i 7 released.
