Try this link: http://www.varietysoftworks.com/jbaldwin/Education/single-level_store.html http://www.varietysoftworks.com/jbaldwin/Education/single-le... The t

Try this link: http://www.varietysoftworks.com/jbaldwin/Education/single-level_store.html http://www.varietysoftworks.com/jbaldwin/Education/single-le... The truth is, most of us that worked on top of OS/400 do not really know what a lot of this means ... just that it is good because IBM told us it was :) In a way, that is what made this a great place to develop applications. You work in RPG (some use COBOL) in languages that are purpose built for working with the built-in database and do not worry about things like memory and where things are stored. The runtime environment and OS handle those details. I was employee 1 at an ISV that made "Change Management" application, what would we be called DevOps today. The way the OS treats everything as objects that have properties we can manipulate and move around was just cool. It was just so straight forward to manage the applications people were creating and deploying, it is hard to explain because it is very different from the *nix/Windows world of how it is done. Even mainframe is not quite the same. The overall system was ahead of its time in many ways. Recall arriving at work in AM (tiny company in a small town) and walking in and having our IBM rep also arrive. Ask why he is there? The system phoned home (via mode) to let IBM know a disk was failing. He has replacement with him to swap in. These systems were expensive, especially for a small company. Recall we had to get a loan so we could buy a tape drive for $25K so we could then put our software onto $50 tapes that we had to mail to customers to let them try or update the software. Some of our bigger customers needed their tapes on a drive that was more like $100K to buy. Thankfully, there were other AS/400 customers within driving distance that would let us come over a couple of times a month and copy our software onto tapes using their drives. When CD-ROM finally became standard it became a god-send for our business.