Expert: Pete Mayhew - 12/10/2009

Question
QUESTION: what is as400? Is it a pc or a server? Please explain clearly?

ANSWER:    I don't know that I (or you) have enough time for me to completely explain the 'AS400', but I'll try to give you an overview.

 It most certainly is not a 'PC'. From the very beginning over 20 years ago, the system (hardware and software) was designed to be a multi-user, multi-tasking machine. If you want to call that a 'server', it would probably be close. IBM tried to stay away from the 'server' designation for a long time, since the system does a lot more than a traditional Windows server. However, they relented several years ago because there was no easy word to describe all the things the AS400 could do, plus 'server' was the corporate buzzword of the day.
 
 To this day, the hardware CPU and chipset and the operating system are IBM proprietary. While there are 'open interfaces' to the OS, third party applications are not allowed to make modifications at the lower code levels. This produces an extremely stable system and hardware that is years ahead of anyone else. As an example, the AS400 was running a 64 bit OS in 1996, 10 years ahead of any Intel platform. The newest CPU chips are dual and quad core, 128 bit, running at 5ghz. The largest 'AS400' (now called System i) can have a 64-way processor complex and 8 terabytes of memory.

To learn about the history of the AS400, find the book 'Fortress Rochester' by Frank Soltis (the 'inventor' of the AS400). Technical information manuals can be found on IBM's Redbook site (www.redbooks.ibm.com). There are hundreds that you can download, covering everything from the hardware to operating system to built-in applications.

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QUESTION: how many as400 systems are there worldwide? Is it similar to IIS server Or Apache, Tomcat servers?
we can publish our developed sites in remote servers. In as400 also we can place those? Explain?

Answer
I don't know the current number-IBM doesn't publish that information. At one time, it was in excess of 750,000. It's probably down to under 500,000 now, but a lot of that is due to consolidation and partitioning (running multiple copies of the operating system on one physical machine). The AS400 supports Apache, Tomcat, and IBM's version Websphere Application server and can run multiple instances of any or all of them. I am not that familiar with the 'web' side of the product, but AS400's are behind the scenes on many high volume websites. I would see no reason why you could not host sites on the AS400 platform.