What Is an AS400? IBM i Hardware and Names Explained
An AS400 is IBM business-computing hardware from a product line that evolved through iSeries and System i into today's IBM Power servers. Use the machine type to identify the exact system and compare compatible replacements.
What an AS400 Is
An AS400 is an IBM business computer from the hardware family IBM introduced in 1988. The original AS/400 combined the server, operating system, database, security, and application environment into one integrated platform.
The AS/400 product name is no longer current, but the platform did not disappear. IBM renamed the hardware through iSeries and System i before bringing IBM i workloads onto the broader IBM Power server family.
AS400, iSeries, System i, IBM i, and IBM Power
These names belong to different stages or layers of the same long-running platform. They are related, but they are not interchangeable in a hardware quote.
How the common AS400 names fit together
| Name | What it describes | What it means now |
|---|---|---|
| AS/400 or AS400 | The original IBM server family and the common name for the platform | Usually signals an IBM i business workload or legacy hardware |
| iSeries | A later IBM server brand | Often describes pre-System i hardware or the wider IBM i environment |
| System i | The server brand that followed iSeries | A hardware generation before IBM combined the Power lines |
| IBM i | The integrated operating system | Runs business applications on supported IBM Power hardware |
| IBM Power | The current processor and server hardware family | Can support IBM i, AIX, or Linux depending on the exact model and configuration |
AS400 Hardware, IBM i, and the Business Application
A useful hardware decision separates the physical server from the operating system and the application. Calling all three the AS400 can hide the detail that decides compatibility.
The three layers in an IBM i environment
| Layer | Example | Why it matters |
|---|---|---|
| Hardware | IBM Power machine type and model | Controls processor, memory, storage, I/O, firmware, and physical support |
| Operating system | IBM i release | Controls which hardware and application versions are supported |
| Application | RPG, COBOL, Db2 for i, or packaged business software | Controls business compatibility, testing, and migration requirements |
How to Identify the Exact AS400 System
The exact machine type and model are the fastest way to move from a general AS400 question to a real hardware answer. The system label, Hardware Management Console, and internal inventory records can provide those identifiers.
- Record the four-digit machine type and the model code
- Confirm the processor generation and serial number
- Check the installed IBM i release and current support level
- Record processor use, memory, storage, backup hardware, and attached devices
- Use the identifier tool before comparing replacement systems
What to Compare Before Replacing AS400 Hardware
A newer server is not automatically a direct replacement. The workload must fit the processor group, IBM i release, application support, storage, backup, interfaces, and planned downtime.
Start with the identifier tool, compare the server generations, then use the product directory for realistic hardware options and price ranges. That order prevents a familiar model name from standing in for a compatible configuration.
Frequently Asked Questions
Is AS400 still used?
Yes. Many businesses still run IBM i workloads that began on AS400, iSeries, or System i hardware. Some remain on older servers, while others have moved the same application environment to newer IBM Power systems.
Is IBM i the same as AS400?
No. IBM i is the operating system. AS400 originally named a server family and is still widely used as the name for the overall platform. A modern IBM i environment normally runs on IBM Power hardware.
Can IBM Power run both IBM i and AIX?
IBM Power supports IBM i, AIX, and Linux, but the supported operating system depends on the exact machine type, model, firmware, and configuration. Check IBM's hardware-to-software maps before planning a move.
Related Resources
Sources
Product catalog pages tied to this IBM Power and AS/400 Server topic.
42U Server Rack with Rail Kit for Power Systems
A full-depth 42U server rack with rail kit sized to support Power server weight and depth requirements.
IBM Power E1150 Enterprise Server
A Power 11 enterprise server for larger IBM i, AIX, and Linux on Power estates that need consolidation, memory headroom, and long support runway.
AS400 Hardware Maintenance Plan
A maintenance and support plan for AS/400, iSeries, and IBM Power hardware where parts access, response time, and lifecycle risk matter.