I am using this system (IBM i) daily. Mostly supporting clients who want to run Node.js (or some other open source package) on there system.
I also maintain a basic IDE for writing code on this OS (replacement for SEU, which was used in the article) and IBM also supply Rational Developer for i.
The OS gets one or two large patches a year, but generally not many new 'features'. I've done and still do my fair share of RPG and ILE C on this system too.
There is documentation for the MI instructions, but that generates an OPM program and not an ILE program on IBM i. Sadly the TIMI isn't really documented anywhere - as well as ILE.
I have written an RPG3 interpreter with all the Record Level Access operations working on a noDb/flatfile in C#, but lost the source after replacing a hard disk. I have also tried writing a RPG4+ (only free format) compiler for .NET, but it started getting tricky when starting to write the RLA operations because they relied on a database. I have the code still, but it's ugly so I never released it.
Would be a fun project, for sure. Not enough hours in the day.
My first long term project (greatest yet) started in January this year. It's an extension to Notepad++ which makes into a lightweight IDE - sort of.
The reason it was created is because the only stable option for developing on this specific platform was to buy an IDE from IBM. My goal is to provide a free option to developers.
This project only started because I couldn't afford the IBM product.
For the last 2.5 years I've been doing RPG - both the newer free form and older fixed. I can imagine I'll be doing it a lot more within the next year also. A lot of people give it hate, but it's a pretty simple language after you use it a lot.
https://marketplace.visualstudio.com/items?itemName=HalcyonT...