The Mid-Level stuff is usually called the ILC or Internal Licensed Code. And OS/400 is the biggest pain in the butt to get ahold of. As a general rule...from IBM, you cannot buy OS/400, i5/os or whatever it is now. It's kinda like SGI, you get a support contract and can then request the media and OS license. IBM only archives the last set of media from and back dated releases...so V3R7, V4R5...but V5 is the current release so all the revs are available.
And if the system supports LPARs...then OS/400 is the hypervisor and all that. I run a 9406-510 at work for my own play thing and have a 9406-170 at home that I run my webserver on.
If you can give me more details as to the Model/type, PRC feature I can give you some more info as to how good of a machine it is. Also if the machine is up, see if you can get the output from a "WRKHDWRSC TYPE(*PRC)" command.
"Two Minus Three Equals Negative Fun" - Troy McClure