Fort Knox terminal In the early 1980s, IBM management became concerned that IBM's large number of incompatible
midrange computer systems was hurting the company's competitiveness, particularly against
Digital Equipment Corporation's
VAX. In 1982, a project named
Fort Knox commenced, which was intended to consolidate the
System/36, the
System/38, the
IBM 8100, the
Series/1 and the
IBM 4300 series into a single product line based around an
IBM 801-based processor codenamed
Iliad, while retaining backwards compatibility with all the systems it was intended to replace. A new operating system would be created for Fort Knox, but the operating systems of each platform which Fort Knox was intended to replace would also be ported to the Iliad processor to allow customers to migrate their software to the new platform. The Fort Knox project proved to be overly ambitious and ran into multiple delays and changes of scope. As the project advanced, the requirement to support IBM 8100 and Series/1 software was dropped. The Silverlake hardware was essentially an evolution of the System/38 that reused some of the technology developed for the Fort Knox project. Silverlake's goal was to deliver a replacement for the System/36 and System/38 in as short a timeframe as possible, as the Fort Knox project had stalled new product development at Rochester, leaving IBM without a competitive midrange system. On its launch in 1986, the System/370-compatible
IBM 9370 was positioned as IBM's preferred midrange platform, but failed to achieve the commercial success IBM hoped it would have. Much like Silverlake, the 9370 also reused the co-processor developed during the Fort Knox project as its main processor and the same SPD I/O bus that was derived from the
Series/1 bus.
AS/400 On June 21, 1988, IBM officially announced the Silverlake system as the
Application System/400 (AS/400). The announcement included more than 1,000 software packages written for it by IBM and IBM Business Partners. The AS/400 operating system was named
Operating System/400 (OS/400). The creators of the AS/400 originally planned to use the name
System/40, but IBM had adopted a new product nomenclature around the same time, which led to the Application System/400 name. First, IBM began prefixing "System" in product names with words to indicate the intended use or target market of the system (e.g.,
Personal System/2 and
Enterprise System/9000). Second, IBM decided to reserve one- and two-digit model numbers for personal systems (e.g.,
PS/2 and
PS/55), three-digit numbers for midrange systems (e.g., AS/400) and four-digit numbers for mainframes (e.g.,
ES/9000). The reassignment of two-digit model numbers from midrange systems to personal systems was to prevent the personal systems from running out of single-digit numbers for new products.
The move to PowerPC IBM announced
RS/6000 in February 1990. Its
RISC technology offered a much better
price/performance ratio than AS/400. Analysts said that IBM intended to let the proprietary AS/400 and
Unix-based RS/6000 compete with each other for midrange customers. IBM Rochester reportedly attempted to make RS/6000 less attractive compared to AS/400. Their extensions to the PowerPC architecture, known as
Amazon (and later as
PowerPC AS), were approved by IBM management instead of the C-RISC design for development into the next AS/400 processor architecture. These extensions include support for tagged memory, as well as assistance for decimal arithmetic. IBM initially attempted to create a single PowerPC implementation for both AS/400 and high-end RS/6000 systems known as
Belatrix. The Belatrix project proved to be too ambitious, and was cancelled when it became apparent that it would not deliver on schedule. Instead, a pair of AS/400-specific processors were designed at IBM Endicott and IBM Rochester, known as
Cobra (for low end systems) and
Muskie (for high end systems) respectively. These became the initial implementations of the
IBM RS64 processor line. The RS64 series continued to be developed as a separate product line at IBM until the
POWER4 merged both the RS64 and POWER product lines together. Despite the move from IMPI to an entirely different processor architecture, the AS/400's
Technology Independent Machine Interface (TIMI) mostly hid the changes from users and applications, and transparently recompiled applications for the new processor architecture. In 1994, the
AS/400 Advanced Series name was used for new models, followed by the rebranding of the product line to
AS/400e (the
e standing for
e-business) in 1997. In 2000, the
eServer iSeries was introduced as part of its
eServer branding initiative. The eServer iSeries was built on the
POWER4 processor from the RS64 processors used by previous generations, meaning that the same processors were used in both the iSeries and
pSeries platforms, the latter of which ran
AIX. In 2004,
eServer i5 (along with OS/400 becoming
i5/OS) the
5 signifying the use of
POWER5 processors, was introduced, replacing the eServer iSeries brand. Successive generations of iSeries and pSeries hardware converged until they were essentially the same hardware sold under different names and with different operating systems. In April 2008, IBM introduced the
IBM Power Systems line, which was a convergence of System i and System p product lines. IBM i is sold as one of the operating system options for Power Systems (along with AIX and Linux) instead of being tied to its own hardware platform.
Legacy Although announced in 1988, the AS/400 remains IBM's most recent major architectural shift that was developed wholly internally. 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, rumored as ending around 1999 with the introduction of
Windows 2000.) == System architecture ==