I was interviewed today for an entry level programming job. I only have knowledge of Python at a basic level, but the hiring manager wants me to learn a little about the development side of AS400 using RPG 400 or RPGFree. I have to send him something I've learned by this Friday.
I'm not sure where to go for resources to learn with or what text editor or IDE I need to use for this. I can't find anything solid online. Do you guys have any suggestions?
As far as I'm aware, there's no IDE for developing in RPG that doesn't require a connection to an AS400. So, in order to really learn how to develop in RPG, you must be able to access an AS400, which is a little inconvenient for newcomers.
There is a free IDE called "RPG Next Gen Editor" that's built on the Eclipse platform. You can check it out here, but as I mentioned above, it requires a connection to an AS400. It's similar in function to IBM's Rational Developer, which is far superior, but the price tag is much better! https://sourceforge.net/projects/rpgnextgen/
Finding resources online for "RPG" can be a little tricky because most of the results you end up getting are for RPG role-playing games. When searching Google for resources on RPG programming, it's helpful to search instead for "RPGLE", which is short for ILE RPG IV.
A good place to start might be here in the IBM wiki: https://ibm.biz/rpgCafe_Freeform_Rpg_Tutorial
Note that this tutorial is VERY basic.
Also see Scott Klement's "How to Learn" page, which lists a few books you can buy that will really help you out if you get the job. I HIGHLY recommend the "Programming in RPG IV" book by Bryan Meyers and Jim Buck. This was the textbook used in a class I took, but it's actually set up in such a manner that you could easily read through the book and teach yourself RPG in a few weeks time. It teaches file design, display file design, and RPG programming, so it's really the whole package with plenty of tutorials and sample programs. https://www.scottklement.com/rpg/howtolearn.html
Good luck, and welcome to the world of RPG!