AS400 OS: What It Is Called Now and How to Check It
The AS400 operating system started as OS/400 and is called IBM i today. Check the installed release and PTF group levels before planning support, software, or hardware changes.
The AS400 operating system is called IBM i today. It started as OS/400, became i5/OS, and took the IBM i name in 2008. Check the installed release and PTF group levels before buying support or planning an upgrade.
AS400 OS Names by Era
| Name | What it names | Era |
|---|---|---|
| OS/400 | The original AS400 operating system | 1988 through 2004 |
| i5/OS | The operating system name used during part of the iSeries and System i period | 2004 through 2008 |
| IBM i | The current operating system name | 2008 to today |
AS400 is still common shorthand for the whole environment. IBM i is the name that matters for release support, software compatibility, and current IBM documentation.
How to Check the IBM i Release on an AS400
Run DSPSFWRSC and press F11 to display release levels for installed software resources. Another option is GO LICPGM, then option 10 to display installed licensed programs and their release levels.
Look for product 5770-SS1, the IBM i operating system. A value such as V7R4M0 means version 7, release 4, modification 0. Record the exact value before checking application support or planning an upgrade.
IBM i Release, Technology Refresh, and PTF Are Different Levels
| Level | What it tells you | Where to check |
|---|---|---|
| IBM i release | The major operating-system level, such as 7.4 or 7.6 | DSPSFWRSC or GO LICPGM |
| Technology Refresh | Hardware support and function delivered within an existing release | The Technology Refresh PTF group and IBM's technology update pages |
| PTF group level | The installed level of grouped fixes and updates | WRKPTFGRP |
A release number alone does not prove that a system has the PTF levels required for new hardware or a software product. IBM divides Technology Refresh delivery into hardware and software updates, so confirm the exact requirement instead of treating one TR label as the whole maintenance state.
Why the AS400 Operating System Still Runs Long-Lived Applications
IBM i combines the operating system, object model, security, work management, and Db2 for i database in one controlled environment. That integration is one reason applications can remain useful for decades while the hardware underneath them changes.
Long compatibility does not remove the need to test. An application may depend on an old licensed program, a vendor-certified release, a device, or code behavior that needs attention before an operating-system update.
An IBM i Update Is Not Automatically a Hardware Upgrade
IBM i runs on supported IBM Power servers. The operating-system release and the server generation are separate decisions, but each limits the other. IBM publishes the current combinations in its IBM i platform support details.
Use IBM i Release History for release and upgrade planning. Use IBM Power Systems Overview for the hardware side.
AS400 OS and IBM i Are the Same Lineage, Not the Same Job
AS400 OS is the phrase people use when they mean the operating system on an AS400-style environment. IBM i is the current product name. AS400 can also refer to the older hardware brand or the whole platform in conversation.
Read AS400 vs IBM i when the naming distinction is the question. Read this page when the question is the operating system itself.