Why Is It Still Called AS400?
AS400 remains the default name because it dominated the market for years, survived every IBM rebrand, and became the shorthand people still use for IBM i environments on IBM Power hardware.
People still say AS400 because the name was in the market for years before IBM started renaming the platform. Administrators learned it as AS/400, vendors sold to AS400 shops, and executives budgeted around the AS400 label. When IBM changed the official product names, the day-to-day language inside companies barely changed.
The Name That Stuck
IBM launched the AS/400 in 1988 and spent the 1990s building one of the most durable mid-range computing installed bases in the world. By the time IBM introduced later brand names, AS400 had already become the default term for the platform in manufacturing, distribution, finance, healthcare, and government environments.
That matters because infrastructure names that survive for a decade rarely disappear cleanly. They become part of hiring language, procurement language, vendor copy, and internal documentation. Even when the official branding changes, the market keeps using the older shorthand.
IBM Renamed the Platform, Not the Workload
The official naming sequence changed, but the platform lineage did not:
- 1988: AS/400
- 2000: iSeries
- 2006: System i
- 2008 to present: IBM i on IBM Power Systems hardware
Those were branding transitions, not platform resets. The operating environment, application base, database model, and upgrade path stayed connected across each rename. That continuity is why many organizations still describe their environment as AS400 even when they are running current IBM i releases.
AS400 Became Search and Conversation Shorthand
AS400 is still the easiest way for many people to describe the entire platform family in one phrase. A plant manager, ERP administrator, or reseller can say AS400 and be understood immediately, even if the specific machine is now an IBM Power server running IBM i.
That shorthand also survives in search behavior. People often search using the older term first, then learn the current IBM terminology after landing on a definition or upgrade article. That is one reason pages such as What Is AS400? and What Replaced AS400? remain important entry points.
What Should You Call It Today?
Use the term that fits the context. If you are speaking historically, AS400 is accurate for the original brand. If you are describing the current operating system, IBM i is the official name. If you are talking about the hardware platform, IBM Power Systems is the correct current hardware brand.
In practice, many teams use all three depending on the audience. A legacy application discussion may still say AS400, while a hardware refresh proposal should use IBM i and IBM Power terminology more precisely.