IBM i (OS/400) the Database Operating System

> Here we reach a point that is simultaneously the platform’s greatest advantage and heaviest burden. Due to such deep integration with dedicated and expensive hardware, IBM i is an “elite” system, in the less positive sense. A mere mortal, computer science student, or enthusiast has no chance to “touch” this system in the comfort of their home. You cannot download an ISO image from the internet, install it on a virtual machine in VirtualBox, or run it on your laptop. The barrier to entry is set at the price level of an IBM Power server, which effectively cuts off the supply of “fresh blood” and makes knowledge of this fascinating architecture passed down almost like guild knowledge, only within large organizations.

I took a course about these back in college. I thought it would be mind-expanding to see how computing could be outside of conventional Windows/Unix/Linux inspired environments, and use something with a very different design. The instructor had a desktop of one of these in his office. I remember logging into an official IBM educational system with a terminal emulator for an assignment.

Unfortunately, the instructor left about a month in, and I switched to a course involving UML modeling for programming Lego Mindstorm robots. Being hands-on with Mindstorms was cool, but I wonder what could have been had I finished the other course.

The article makes me feel the author doesn’t have a deep understanding of some of the mechanisms. TIMI, iirc, is similar to Java (or Smalltalk) bytecode. I’m not sure it’s translated to native instructions on install or on module load, but the native code is kept so that the compilation doesn’t need to happen again. It’s as if the JVM saved a .nativeclass file when a .class file is loaded (kind of one level lower than what Python does, turning a .py file into a .pyc, or .pyo).

The concept of a flat object space we saw in Smalltalk and Lisps (the “system image”) would be seen again, kind of, in the Newton, the Palm, and, IIRC, in Taligent’s Pink. It’s a shame the IBMi is so poorly documented (in sharp contrast with its Z big brother) that no emulator capable of booting OS/400 images exists.

It’s not that this approach is perfect though - it’s really hard to bootstrap a Smalltalk image from scratch. I assume making an IBMi image without a running IBMi system would be similarly challenging.

I'd recommend people read "Inside the AS400" by Frank G. Soltis, as the concepts behind the OS are quite strange and unlike anything else I've ever seen. Unfortunately paper copies are pretty expensive, but there's a high quality PDF floating around on Bittorrent.

IBM i was k8s before k8s, with fewer yaml files and better backwards compat

Some of my first exposure to enterprise IT was via the AS/400 and served as a fantastic basis for the cloud stack and agents of today.