The i OS is very different than UNIX and this book was quite enlightening to me. Some of the stuff done is quite visionary. The hardware micro-architecture has fundamentally changed four times, but the upper OS and users doesn't care.
I'm happy to see this. I'm only in my 20s so I haven't grown up with mainframe computing in my life, but I did get to use both an AS/400 and z/OS about 5 years ago. I've been tweeting and emailing into the dark asking IBM to just provide a free VM of one of these so I can at least play around and learn about them more. I was just getting into assembly on one when I lost access.
Having had the privilege of working with 2 different AS/400 systems (one a v4 and another a v6), I can say these guys are really bullet proof.
Rarely are the OS level issues -- almost all of our issues have been hardware (hdd's failing, not surprising though), or our vendor app messing up (too frequent to be happy about, but hey, it's written in RPG V, so can't complain too much).
The problem with learning to work with an AS/400 system is that they are ludicrously expensive to get your hands on -- So I am very glad to see something like this out there in the wild.
Well this brings back memories. I took an AS/400 class in college (local tech school) since that was the only way to learn SQL back then; none of the other CIS classes offered database programming. The class was geared towards prepping the student for working at one of two companies in the area that hired AS/400 programmers, so it was very narrowly focused to their needs.
I have to say, that was a simultaneously challenging and frustrating experience. It soured me on being a programmer of any sort, and I ended up shifting to network administration as a field of study. I'm glad I did.
All that said, this seems like a generous and handy service for those who need it.
There is still great pay if you are an AS/400 guru. About 3 years ago I interviewed for a job where I would be maintaining code which was running on an AS/400 running in System 36 emulation mode. The code had been certified by the government for a 50 year contract. The 3 previous employees had all died. Which didn't make me anxious to take the job, but the pay was $450k a year. And with job security through 2030 it had some appeal. But what do you do after?
"I have experience with 50 year old software" is kind of like the resumes people send me saying they know Office XP and Word Perfect.
Sure if you can fix the things nobody else can you can charge top dollar, but eventually the last of those things come out of service.
Do you really need to do something "after" if you earn 450k$/yr for few years?
In an ideal work I'll probably take that job, ask for 80% part-time and use the remaining 20% of the time to maintain my brain active :)
BTW in my previous companies (banks) we were using banking software running on AS/400 (and DB2) and interfacing from IIS/SQL Server via OLEDB for querying the data / executing stored procedures. Actually the service was hosted, but I'm quite sure the AS/400 developers were taking 1/10 of that amount... ;)
RZKH welcomes all friends and people interested in AS400. It's always the same situation - when they come from the unixoid world - they are confused. But you should stay on the path and learn some bit about AS400 (or IBM i as they are called now). It's the only commercially used 128Bit operating system with high level security and low level problems :)
We used one of these at my old job, well the IMB iSeries but the database was started in the early 80s. Fun times, all the employees where still on green screen when I was there (2011-2012). We started to move everyone to a web application that accessed the AS/400 data.
It depends. If you have only traditional RPG/400 etc experience there are 10 programmers for each job, yes. But, in this marketplace, if you have experience with (traditional) RPG but also modern techniques like OO, Java, etc, you have lots of work for the coming decennia i assure you. These systems don't disappear, but they do have to be "modernized" and refitted to accommodate the changing environment. There is demand for it, but business do not know it's a modern system for which you can build modern software. The traditional RPG programmer will say something like "well XML and web services etc is too difficult, let's just use CSV and FTP like always". These days it's called "IBM i" and you can do about anything with it, there's even a port of node.js for example. It also has a binary compatible AIX subsystem which integrates with the rest. You can even call it (from a programmer's standpoint) - and it officially is - a UNIX system (POSIX compliant that is). Etc. When you see a green screen you see old software, not an old system that only supports green screens. And there are still more than 100.000 individual customers/companies using this system. And lots and lots of old RPG code, which only grows.
One of the more unique aspects of the AS/400 is the single level store. I haven't ever used it, but the general idea is that it does away with the file system in exchange for a single, flat address space. This simplifies the programming model.
The AS/400 also runs something like bytecode, rather than directly on the hardware. This has given IBM the flexibility to change the underlying architecture in fairly radical ways. (new CPU ISAs, etc.)
Historically, the AS/400 has some significance to IBM beyond the fact that it's been a commercial success. After IBM did so well with the System/360, they started work on the next big thing: IBM Future System. The idea was that FS was something only IBM could do, because only IBM had the research budget and staff to pull it off. As these things often go, FS didn't achieve its grander goals, but it did spin off several technologies that IBM did commercialize. In addition to several System/370 processors, the Future System work also ultimately resulted in the AS/400.
AS/400 descended from S/38, but is not the same. In particular the System/38 architecture had capability-based addressing¹ — essentially, you can perform a particular kind of access if and only if your pointer contains the necessary permission.
"in June 1988, IBM announced the results of Silverlake as the Application System/400, or AS/400. In many ways, the box was a repackaging of the System/38, with some left over Fort Knox parts,"
Brian Kelly was an IBM Midrange Systems Engineer for 30 years, and has spent nearly a decade as a System i5 consultant based in Scranton, Pennsylvania. He is also author of thirty AS/400, iSeries, and System i5 books and he serves as an assistant professor at Marywood University, which uses the OS/400 and i5/OS platform and teaches courses in the box as well.http://www.itjungle.com/tfh/tfh040708-story05.html
My point was that the S/38 used some of the detritus from Fort Knox not, directly, the AS/400.
Quite a lot of work went into the AS/400 so it wasn't just a renamed S/38, but any discussion of the AS/400 should recognize its origins.
I worked on AS/400s for 10 years and still consider it the most productive environment I've ever used. Uptime was indeed legendary - our IBM rep told me he knew of an AS/400 running at another site that had been up for over 7 years.
I spent about a week as an AS/400 operator in-training (they hired me for an available IT position while they worked on getting the real position created). Training was basically a list of "press 3 at 10pm; press Z at 10:02pm; wait 15 minutes".