IBM i and AS400 Resource Library | AS400IBMSystems.com

AS400 History Timeline

This AS400 timeline tracks the platform from IBM's June 21, 1988 announcement through the 1995 RISC shift, the iSeries and System i rebrands, IBM i 7.5 and 7.6, and Power 5 through Power 11 milestone dates.

AS400 Login Explained

AS400 login usually means signing in to an IBM i user profile, most often through a 5250 green-screen session, IBM i Access Client Solutions, or a modern web interface tied to the same IBM i system.

AS400 Power Requirements

AS400 power requirements can mean either electrical requirements for the hardware or processing capacity requirements for the workload. The exact answer depends on whether you are discussing a legacy AS400 cabinet or a modern IBM Power replacement.

AS400 vs iSeries vs System i

AS400, iSeries, and System i are not separate product families. They are successive IBM brand names for the same platform lineage that now continues as IBM i on IBM Power Systems hardware.

Why Is It Still Called AS400?

AS400 remains the default name because it dominated the market for years, survived every IBM rebrand, and became the shorthand people still use for IBM i environments on IBM Power hardware.

AS400 API Integration

Exposing existing RPG and COBOL program logic through APIs lets an AS400 or IBM i system connect to mobile apps, e-commerce platforms, and partner systems without rewriting decades of business logic. This is usually the highest-leverage modernization step an IBM i shop can take.

AS400 Application Modernization

Application modernization, refactoring RPG into free-format ILE code, modularizing monolithic programs, and introducing new languages alongside existing logic, is the broadest and highest-risk modernization category. It is also the one most often confused with a full migration, when the goal is almost always to extend the application's life, not replace it.

AS400 Cloud Integration

IBM i does not run on general-purpose public cloud infrastructure, but that does not mean AS400 environments are cut off from cloud services. Backup and disaster recovery, hybrid application architectures, and IBM's own Power-based cloud hosting are all realistic paths.

AS400 Database Modernization

Many AS400 databases still rely on decades-old DDS-described physical and logical files. Converting them to modern SQL-defined DB2 for i tables and views unlocks standard tooling, better performance options, and easier integration, without requiring a database migration to a different platform.

AS400 Migration Myths

"AS400 is dead," "nobody knows RPG anymore," and "modernizing means migrating" are among the most persistent myths driving unnecessary and expensive AS400 migration decisions. Here is what each claim gets wrong.

AS400 Model History

IBM launched the AS/400 in 1988 as a single integrated hardware and software system. The AS400 model line ran for roughly a decade, spanning the original CISC-based systems and the mid-1990s transition to RISC hardware, before the platform was rebranded iSeries in 2000.

AS400 Modernization Explained

AS400 modernization means updating how an IBM i environment looks, connects, and is built, not replacing the platform underneath it. Understanding the five modernization categories, and picking the right one for the actual problem, is the difference between a focused project and an over-scoped migration.

Green Screen Modernization

Replacing the 5250 green screen interface is usually the first modernization step organizations take, because it is visible, relatively low-risk, and does not require touching the underlying RPG or COBOL logic. Screen wrapping, rehosting, and native web front ends are the three main approaches.

IBM i Licensing Explained

IBM i licensing is tied to the processor tier of the underlying IBM Power hardware, not just to core count or user seats. Understanding software tiers, program license terms, and how licensing carries across a hardware upgrade is essential before budgeting a Power Systems project.

IBM i Modernization Options

Modernizing IBM i almost never means leaving the platform. The real options fall into five categories: interface modernization, API enablement, cloud integration, database modernization, and application modernization, each addressing a different pain point without a rip-and-replace migration.

IBM i Operating System Explained

Beyond the definition, IBM i works differently under the hood than Windows, Linux, or UNIX: work management runs through subsystems and jobs, changes are applied through PTFs, and system startup follows an IPL rather than a simple reboot. This is how it actually operates day to day.

IBM i Release History

From OS/400 V1R1 in 1988 through IBM i 7.5 today, the IBM i version lineage spans nearly four decades under three different names. This is the release timeline, from the original AS400 operating system to the current version.

IBM has continued to invest in IBM i through regular OS releases, Technology Refreshes between major versions, and certification on each new Power Systems generation, most recently Power11. This is what that pattern of investment looks like and what it signals for planning purposes.

IBM i Security Basics

IBM i has a strong security reputation built into its object-based architecture, but that reputation has led many organizations to under-invest in configuration. Security levels, user profiles, object authorities, and exit points are the core concepts worth understanding.

IBM i Support Status

IBM publishes fixed end-of-support dates for each IBM i release. IBM i 7.3 support ended in April 2026; IBM i 7.4 is supported through April 2028 and IBM i 7.5 through April 2030. Knowing where a specific release stands is the first step in any support or upgrade planning conversation.

IBM Power Sizing Basics

Sizing an IBM Power system means matching processor CPW, memory, and storage to a workload, plus the correct IBM i software tier, with enough headroom for growth. This guide covers the basic concepts IT teams need before evaluating an AS400 or older Power hardware upgrade.

IBM Power Systems Overview

IBM Power Systems is the hardware brand IBM introduced in 2008 to unify its Power-processor-based servers, replacing the earlier System i and System p lines. It is the hardware platform that runs IBM i, AIX, and Linux workloads today, including the modern successors to AS400 environments.

iSeries Model History

IBM renamed the AS400 platform iSeries in October 2000, as part of its e-business branding strategy. The iSeries model line ran through 2006, including a 2004 refresh onto POWER5 processors under the iSeries i5 name, before IBM renamed the platform again to System i.

IBM Power P05 Generation Comparison Dataset

A structured, downloadable dataset comparing CPW, memory bandwidth, internal storage, and PCIe capacity across the IBM Power11 S1112 and the Power10, Power9, and Power8 systems in the IBM i P05 software tier.

System i Model History

IBM renamed the iSeries platform System i in 2006, aligning it with the System p, System x, and System z brand family. System i was the last name the AS400 lineage carried before IBM split the OS and hardware brands into IBM i and IBM Power Systems in 2008.

IBM i is the operating system that runs on IBM Power Systems hardware. It is the direct software descendant of OS/400, the operating system IBM shipped with the original AS400 in 1988, and it still runs applications written for that platform decades ago.

When Not to Migrate Off AS400

Migration off AS400 is sometimes the right call, but it is decided correctly far less often than it is proposed. Heavy custom business logic, strong database reliability requirements, and unclear replacement ROI are the clearest signals that modernization, not migration, is the better investment.

IBM's original official brand spelling for the Application System/400 platform introduced in 1988. AS400 is the later slashless shorthand and search form.

A common spaced search and voice-typing version of IBM's Power10 product name. Not IBM's official styling, but widely used by searchers.

A common spaced search and voice-typing version of IBM's Power11 product name. Not IBM's official styling, but widely used by searchers.

A common spaced search and voice-typing version of IBM's Power9 product name. Not IBM's official styling, but widely typed by real users.

IBM's official no-space styling for the 2021 Power generation. Power 10 with a space is a common user-typed variant of the same product family.

IBM's official no-space styling for the 2017 Power generation. Power 9 with a space is a common search and voice-typing variant of the same hardware family.

BigTech Reseller IBM Section

BigTech Reseller's IBM section helps buyers discover IBM Power resellers, IBM i solution providers, AS400 upgrade resources, storage options, and related IBM ecosystem coverage.

AS400 is a hardware brand name from 1988. IBM i is the current official name for the operating system that runs on IBM Power hardware. They are the same lineage, different names. Understanding the distinction matters for licensing, support conversations, and upgrade planning.

IBM Power 11 Overview

IBM Power11 is the latest generation of IBM Power Systems hardware, announced July 8, 2025. Power11 delivers new performance gains, energy efficiency improvements, and full compatibility with IBM i workloads from AS400-era applications forward.

Is AS400 Still Used?

Yes. AS400 ... now called IBM i on IBM Power Systems ... is still actively used by thousands of organizations worldwide. IBM continues to invest in the platform with new hardware releases and OS updates.

AS400 is IBM's mid-range business computing platform introduced in 1988. Despite multiple name changes over the decades, AS400 remains the most widely used search term for IBM i, iSeries, and IBM Power systems worldwide.

What Replaced AS400?

IBM i on IBM Power Systems hardware replaced the AS400. The operating system evolved through iSeries, System i, and IBM i naming. IBM Power10 and Power11 are the current hardware generation. The workloads never disappeared ... only the brand names changed.

The slashless form of IBM's original AS/400 brand name. Not the original official styling, but now the dominant search, typing, and colloquial shorthand for IBM i and IBM Power Systems.

Commercial Processing Workload. IBM's benchmark metric for measuring the relative processing performance of IBM i systems. Used to compare AS400/IBM i hardware generations and models.

The integrated relational database built into IBM i (AS400). DB2 for i is not a separate product ... it is part of the OS. One of the AS400 platform's defining architectural advantages.

The text-based character interface used to interact with AS400 and IBM i systems. Named for the green monochrome display terminals originally used. A key modernization target.

The current official name for the operating system that runs on IBM Power Systems. Successor to OS/400 and i5/OS. The OS lineage of the AS400 platform.

IBM Power Systems

The IBM server hardware platform that runs IBM i (and AIX and Linux). The hardware successor to the AS400, iSeries, and System i platforms.

The brand name IBM used for the AS400 hardware platform from 2000 to 2006. Replaced by System i in 2006 and IBM Power Systems in 2008.

The original operating system for the AS400 platform, released in 1988. Renamed to i5/OS in 2004 and IBM i in 2008. The OS lineage that all IBM i releases trace back to.

IBM's official no-space styling for the Power generation IBM announced July 8, 2025. Brand-correct in IBM materials, while Power 11 with a space is also common in search and voice typing.

IBM's primary programming language for AS400 and IBM i. Report Program Generator, now evolved into a modern structured language (ILE RPG / RPGLE) still in active use.

IBM's brand name for the AS400/iSeries platform from 2006 to 2008. Part of IBM's unified Systems branding. Replaced by IBM Power Systems.

AS400 Basics FAQ

Answers to the most common AS400 questions from IT professionals, executives, and administrators new to the IBM i platform.

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