[skissane]

So, my impression, is many applications for AS/400 are written in RPG or COBOL, languages which in their AS/400 implementations treat "files" really no differently than they do on any other platform. Or, similarly, DB2/400 stores database tables as these single-level store objects underneath, but to a programmer writing SQL queries, it doesn't really make much difference – the experience is pretty similar to writing SQL queries for DB2 for z/OS, DB2 for LUW, or DB2 for VSE/VM (and what differences do exist are more due to the divergent code bases of the different products than due to the single-level store.)

I get the impression that S/38 and OS/400 have some really interesting concepts at the core of the OS, but it is questionable how well the higher levels layered on top leverage those concepts.

"Everything is an object" would be a lot more powerful if IBM let customers/ISVs define their own object types, when as far as I am aware they don't. Yet IBM will define dozens upon dozens of object types for all kinds of obscure requirements, many of which are no longer even relevant today [1][2].

[1] https://www.ibm.com/support/knowledgecenter/en/ssw_ibm_i_74/...

[2] https://www.ibm.com/support/knowledgecenter/en/ssw_ibm_i_74/...