What is IBM i?

For older generations of enterprise tech experts, the IBM i platform is, without stretching the point, legendary. Initially released back in the end of the 1980s, IBM i is still very much relevant and relied upon today. Unmatched level of security, great performance and ease of deployment and maintenance are some of the core features of IBM i that made it the legend it is now. 

For younger users, customers, and sometimes even software specialists, IBM i and related technologies can be a real mystery. And this is not surprising as properly defining the IBM i platform and understanding its deep and intricate ecosystem is not so easy. 

Here’s a brief, straight-to-the-point summary of everything you always wanted to know about IBM i but didn’t have time and/or energy to research and learn. 

What is IBM i? 

What today is most often referred to as IBM i is an operating system, originally developed by IBM for its AS/400 line of systems. The initial name of the system was OS/400. In 2004, IBM rebranded this solution as i5/OS. In 2008 its name was changed again, to the current one — IBM i. The “i” in its name stands for “integrated.”

What is IBM AS/400?

Since we are talking about IBM i, it makes a lot of sense to also briefly explain about AS/400 and how it is different from the operating system.  

IBM AS/400 (“ÄS” stands for “Application System”) is a line of midrange computers by IBM initially released in 1988. AS/400 was created as a successor to System/36 and System/38 platforms by IBM. Based on the OS/400 operating system, AS/400 were very successful on the computer market upon the release, mainly due to high level of performance and lower cost compared to predecessors. According to official reports, IBM managed to sell 250,000 AS/400 systems by 1994 and 500,000 by 1997. 

Main distinctive features of AS/400 and IBM i

The architecture of AS/400 is defined by five main principles that are fundamental to this platform and its ultimate huge market success. 

Technology independence

The so-called Technology Independent Machine Interface (TIMI), platform-independent instruction set architecture (ISA), compiled along with the native machine language instructions, is the key concept behind the AS/400 platform. TIMI was used by the architectures of AS/400 to transform the underlying processor architecture without breaking application compatibility.

Software integration

The OS/400 operating system, later rebranded and now known as IBM i, was another key component and strength of the AS/400 platform. As the only operating system supported by the original AS/400 hardware, many of the most advanced features of AS/400 were implemented in this OS instead of the underlying hardware. Some of the most notable features included the support of multiple users, RDBMS database (now known as Db2), menu-driven interface, printers, etc. 

Additionally, OS/400 had a block-oriented terminal support implemented though green-screen 5250 applications, which today are also a legend in the enterprise IT ecosystem. Famous for their incredibly reliable performance and great security, 5250 green-screens did become a legacy over the time. Which is why they need to be modernized in our age of digital transformation and Industry 4.0 technologies. 

Single-level store virtual memory 

Single-level store virtual memory support also was a key element of the AS/400 platform architecture. As opposed to S/38 and CISC AS/400 that had 48-bit processors, in AS/400, the virtual address resided in the rightmost 64 bits of a pointer. The essence of the single-level store concept is in referencing the main memory and disk as a single address set by the 64-bit address space. 

Object-based design

Object-based design, when everything is an object with built-in persistence and garbage collection, was another major innovation introduced by AS/400 and its operating system. Prior to the release of the early version of IBM i, Unix-based systems relied on “everything is a file” software architecture style. 

Third-party operating systems support 

Soon after the release of the original AS/400, in later generations, the support of third-party operating systems was integrated into the hardware. The list of supported operating systems included Microsoft Windows 2000 and Windows Server 2003, Linux, SSP, AIX, and others. 

Why is IBM i legacy modernization a must in 2023?

Despite being a breakthrough in enterprise IT technologies back in the end of the 1980s, most original technological components of AS/400 and OS/400 got significantly outdated in about a decade or so. Today, they are undeniably a legacy and require modernization as soon as possible. 

You can learn more about IBM i modernization in our previous articles: 

LANSA’s custom-made tools for IBM i modernization 

Visual LANSA is a low-code, rapid application development platform for building enterprise-grade mobile, web and desktop apps. LANSA’s platform has been a key component powering the successful delivery of IBM i modernization projects for hundreds of organizations throughout the years. Utilizing Visual LANSA allows organizations of all sizes to use their existing development resources to build new apps and integrate them with other parts of their IT systems. 

Using LANSA’s high-level language, the same skills can be applied to write client-side code, server-side code, and everything in between. LANSA saves organizations the expense of hiring costly specialized software developers to deliver a modernization project or create a new app. It allows even developers with limited skills and experience to contribute to the app creation process without worrying about the technical aspects.

LANSA incorporates a variety of powerful tools, including several instruments that were created for the IBM i platform, with a goal to make the modernization of IBM i apps and related systems as easy as possible. 

RAMP (Rapid Application Modernization Process)

Rapid Application Modernization Process (RAMP) is an incremental modernization approach that implements the best of refacing existing applications and new development. By consolidating existing functionality with new capabilities inside RAMP’s application framework, you get to have the applications you want without having to throw everything away. Modernization is performed in stages, new functionality can be introduced incrementally without serious impact to business operations, and the user interface becomes consistent across all of the applications.


Portalize is a fully functional, fully customizable portal framework loaded with the most essential features. By providing pre-maid portal components, it simplifies the creation of app portals and saves your developers from the need to code complex portal features. 

The framework incorporates a wide range of pre-built administrative features that can be integrated into a modernized IBM i app. Admins can easily manage user accounts, and they have full control over security and notification settings. They can control session logging as well as turn Google Analytics on or off at will. Whether you have a few, a few hundred, or a few thousand users, Portalize’s admin features will make keeping control of your portal’s users a snap. 

Portalize allows you to enable request validation checks for enhanced security. As well as IP monitoring and banning to reduce attempts and thwart attacks; set login attempts; and have full control over the number of security questions or the actual questions asked.


aXes is one of LANSA’s solutions created for IBM i users specifically. aXes is a tailor-made tool designed to automate the creation of web-enabled IBM i applications. It allows organizations to easily transform their existing IBM i 5250 apps into web pages out-of-the-box, without changing source code. 

aXes includes an API that allows developers to create programs able to automatically operate applications written with RPG or COBOL. Additionally, applications can use aXes to simulate the actions of a person entering data on screens in an IBM i application. This feature makes it possible to integrate existing 5250 apps with .NET, Java and other platforms without changing their source code. aXes caters for a wide range of automation options with versions of the API for .NET for Windows, Java for IBM i and Windows, and RPG for IBM i.

LANSA is your trusted guide to IBM i app modernization 

IBM i modernization is an overwhelming process that can either make or break a company. That’s why planning and strategizing for IBM i modernization is so important. We combined all the fundamental knowledge about the enterprise application modernization in one whitepaper titled “Application Modernization For Dummies, LANSA Edition.” You can download it for free on this page

Ready to begin? Get in touch with us to start utilizing Visual LANSA for your app development and modernization needs.

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