A Walk Down Memory Lane
As I prepared for this week’s blog about IBM POWER servers, I was fascinated by my initial Google research and fondly recalled curious aspects of the IBM POWER (iSeries/AS400) history before and after its initial introduction.
My sense is that many readers will also remember the evolution of this remarkable system and its history.
Disclaimer: IBM i is an operating system, just like OS400. iSeries and AS400 are IBM server brand names. I use these terms interchangeably to make is easy for researching information via the web.
AS400 Starts In 1988
The AS400 platform was introduced on June 21, 1988. It was later renamed iSeries in 2000. In 2008, the server was rebranded as the IBM POWER System (also supporting AIX and Linux) and OS/400 was rebranded IBM i in 2008.
Where Did The Acronym POWER Come From?
By the way, the acronym POWER comes from Performance Optimization With Enhanced RISC, an IBM proprietary design. In 1992 Apple, IBM and Motorola formed the AIM alliance to develop a mass-market version of the POWER processor. This resulted in the “PowerPC architecture”, a modified version of the POWER architecture. Curiously, the variations of POWER have also found their way into home video games.
How Did IBM AS400 Get Called Silverlake?
The code name of the AS/400 project was “Silver Lake”, named for the lake in downtown Rochester, Minnesota, where development of the system took place.
What Came Before The AS400?
The predecessor to AS/400 was IBM System/38, first made available in August 1979 and marketed as a minicomputer for general business and departmental use. It was sold alongside other product lines, each with a different architecture (System/3, System/32, System/34, System/36).
Why Did IBM Pick “AS” For AS400?
AS stands for “Application System”. Realizing the importance of compatibility with the thousands of programs written in legacy code, IBM launched the AS/400 midrange computer line in 1988. Great effort was made during development to enable programs written for the System/34 and System/36 to be moved to the AS/400.
What Contributes To The IBM i Longevity?
One feature that has contributed to the longevity of the IBM System i platform is its high-level instruction set (called TIMI for “Technology Independent Machine Interface” by IBM), which allows application programs to take advantage of advances in hardware and software without recompilation. TIMI is a virtual instruction set independent of the underlying machine instruction set of the CPU. User-mode programs contain both TIMI instructions and the machine instructions of the CPU, thus ensuring hardware independence. This is conceptually somewhat similar to the virtual machine architecture of programming environments such as Smalltalk, Java and .NET. The key difference is that it is embedded so deeply into the AS/400’s design as to make applications effectively binary-compatible across different processor families.
TIMI Provides For Technology Independence
Unlike some other virtual-machine architectures in which the virtual instructions are interpreted at run time, TIMI instructions are never interpreted. They constitute an intermediate compile time step and are translated into the processor’s instruction set as the final compilation step. The TIMI instructions are stored within the final program object, in addition to the executable machine instructions. This is how application objects compiled on one processor family (e.g., the original CISC AS/400 48-bit processors) could be moved to a new processor (e.g., PowerPC 64-bit) without re-compilation. An application saved from the older 48-bit platform can simply be restored onto the new 64-bit platform where the operating system discards the old machine instructions and re-translates the TIMI instructions into 64-bit instructions for the new processor.
IBM i May Be The Final IBM Wholly Internal Development…And It Has Been Magnificent
Although announced in 1988, the AS/400 remains IBM’s most recent major architectural shift that was developed wholly internally. Since the arrival of Lou Gerstner in 1993, IBM has viewed such colossal internal developments as too risky. Instead, IBM now prefers to make key product strides through acquisition (e.g., the takeovers of Lotus Software and Rational Software) and to support the development of open standards, particularly Linux.
It is noteworthy that after the departure of CEO John Akers in 1993, when IBM looked likely to be split up, Bill Gates commented that the only part of IBM that Microsoft would be interested in was the AS/400 division. (At the time, many of Microsoft’s business and financial systems ran on the AS/400 platform, something that ceased to be the case around 1999, with the introduction of Windows 2000.)
Excited to learn more about IBM i? Contact me at 714-593-0387 or email me at [email protected].
