OS/400 is an operating system used on IBM's line of AS/400 (now called iSeries) minicomputers. OS/400 and AS/400 were introduced in 1988. The latest version of OS/400 is now called i5/OS.

OS/400 and i5/OS have built-in subsystems that provide some backward compatibility with earlier IBM general business systems, such as the IBM System/3x series.

IBM designs i5/OS as a "turnkey" operating system, requiring little or no on-site attention from IT staff during normal operation. For example, i5/OS has a built-in (and quite powerful) DB2 database which does not require separate installation and maintenance. System administration has been wizard-driven for years, even before that term was defined. i5/OS is also well regarded for its tuned Java implementation, including specific hardware optimizations.

i5/OS can coexist on modern iSeries and pSeries hardware alongside AIX and Linux.

External links

• iSeries (IBM)
• midrange.com -- i5 / iSeries / AS400 technical discussion mailing lists and more