IBM i and the AS/400 story
IBM i is the operating system that grew out of the AS/400, launched by IBM in 1988 for mid-sized businesses. It now runs on IBM Power servers. Its design is unusual: everything is an object, all storage is one address space, and a full relational database is built in. Many distributors, manufacturers, retailers and banks still run their core systems on it.
Many names, one platform
| Years | Hardware name | Operating system name |
|---|---|---|
| 1988 | AS/400 (Application System/400) | OS/400 |
| 2000 onwards | eServer iSeries, then System i | OS/400, then i5/OS |
| 2008 onwards | IBM Power servers (shared with AIX and Linux) | IBM i |
People still say "AS/400" for the whole platform. In a job advert, AS/400, iSeries, System i and IBM i usually mean the same skills.
What makes it different
- Everything is an object: programs, files, user profiles, job queues and libraries are all objects with a type, such as *PGM, *FILE or *USRPRF. The system only lets you use an object in ways its type allows.
- Single-level storage: memory and disk form one large address space. Programs refer to objects, and the system decides what is in memory and what is on disk.
- TIMI: the Technology Independent Machine Interface sits between programs and the hardware, so programs have moved across processor generations without being rewritten.
- An integrated database: Db2 for i is part of the operating system, so every file is a database table with SQL access.
Where it is used
IBM i runs order processing, warehouse, manufacturing, retail, insurance and banking systems, often for decades with very small operations teams. It shares IBM's business focus with z/OS: reliability, security, backward compatibility and long-lived applications, at a different scale.
In what year was the AS/400 launched?
Show a hint
Late 1980s.
Show the solution
1988.
Common mistakes
IBM continues to release and support IBM i on current Power servers, with SQL, open source tools and web interfaces.
They are the same line; the names changed over time.
On IBM i, files are database objects with fields and record formats.
What you will see at work
- IBM i teams are often small, so people combine development, operations and database work.
- Skills in RPG, CL and Db2 for i are in steady demand, partly because many experienced people are retiring.
- Mainframe skills such as batch thinking, job logs and green-screen navigation help when moving into IBM i work.
Key terms
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