AS400 begat iSERIES begat IBM i

The IBM AS400 ruled for years. But like all good things, it eventually needed an upgrade.

It’s successor, the IBM iSeries was used up until early 2000’s – this was really a re-branding along with some hardware upgrades. This line was sometimes called AS/400e and eServers but continued to run the branded OS/400 operating system.

In a half hearted attempt to clear the confusion the IBM System i re-branding also changed the name of OS400 to i5/OS (but many of the menus on the system still called it AS400) – so it’s easy to get confused.

AS400 history

The old AS/400 range was finally put to the bed with the launch of IBM POWER SYSTEMS – this hardware is hugely changed from the old AS400 machines.

Modern architecture means this range of IBM POWER SYSTEMS really doesn’t even compare to the old creamy AS400 boxes of old. Think of the changes in mobile phones in the last thirty years and this will give you idea of the ground shaking advances.

Modern IBM Power Systems are logically partitioned and can run multiple operating systems at once – arguably the most common is “IBM i” – this is a modern version of OS/400 (the operating system and database on the old *400* machines).

Thirty Years of System Evolution

  • 1988 AS/400 (Application System/400) running OS400
  • 1994 AS/400 (Advanced Series/400) running OS400
  • 2000 iSeries running OS400
  • 2004 System i running i5/OS
  • 2008 Power Systems running IBM i

Or in pictures it’s (roughly)  like this:

ibm system 38
The IBM System 38 – before the IBM System 40 (aka AS400)
AS400 B60
The IBM AS/400 is born. It’s big, creamy and like something out of Star Trek
AS400 C10
As the AS400 evolved it got smaller and faster
AS400 history 1
The iSeries was way more powerful and a modern slinky new black shade
AS400 history 2
The IBM System i – was just a re-polished iSeries really… with some go faster stripes
AS400 history 3
bringing us to the current generation of IBM POWER systems running the beautifully slick IBM i operating system

Obviously, the #IBMi operating system is hugely upgraded from the old OS400 – but it’s beautifully 100% backward compatible.

IBM i’s main programming language (RPG) being upgraded so much it’s barely recognizable from the old RPG logic cycle days. But the beauty of RPG is that you can still sit down today and write old-fashioned 3 line RPG programs using the logic cycle if you wish.

IBM i is totally backward compatible and will still run programs written 20, 30, 40 years ago.

The AS400 is Dead - Long live IBM i

IBM i running on POWER SYSTEMS is the backbone of most big businesses out there today.

AS400 history from AS/400 to iSeries to IBM i On Power Systems

I’m typing this from Las Vegas where every casino and hotel is powered by IBM POWER SYSTEMS.

Next time you hear someone refer to their current IBM i System as “the 400” you can gently correct them 😉

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