AS400 Learning Center
Foundational answers about the AS400 platform ... what it is, why it persists, and how it connects to modern IBM i and IBM Power systems.
The AS400 name has outlasted every official IBM rename. This section covers the fundamentals: what AS400 means, why organizations still run it, how the terminology evolved, and what the path forward looks like.
Articles in This Hub
AS400 vs IBM i
AS400 is a hardware brand name from 1988. IBM i is the current official name for the operating system that runs on IBM Power hardware. They are the same lineage, different names. Understanding the distinction matters for licensing, support conversations, and upgrade planning.
Is AS400 Still Used?
Yes. AS400 ... now called IBM i on IBM Power Systems ... is still actively used by thousands of organizations worldwide. IBM continues to invest in the platform with new hardware releases and OS updates.
What Is AS400?
AS400 is IBM's mid-range business computing platform introduced in 1988. Despite multiple name changes over the decades, AS400 remains the most widely used search term for IBM i, iSeries, and IBM Power systems worldwide.
What Replaced AS400?
IBM i on IBM Power Systems hardware replaced the AS400. The operating system evolved through iSeries, System i, and IBM i naming. IBM Power10 and Power11 are the current hardware generation. The workloads never disappeared ... only the brand names changed.
Topics Covered
- What is AS400?
- Is AS400 still used?
- Why is it still called AS400?
- What replaced AS400?
- AS400 vs IBM i
- AS400 vs iSeries vs System i
- AS400 history timeline
- AS400 login explained
- AS400 power requirements