The AS400 Evolution: How IBM's Legacy System Is Adapting to the Future
IBM iSeries AS400 systems have evolved continuously for over 50 years. These systems adapt to changing business needs while their core reliability remains intact. Many enterprises still rely on these legacy systems for their proven performance and resilience.
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IBM i services continue to show a strong market presence. The 2025 IBM i Marketplace Survey shows that 96% of users get better ROI from IBM i platforms than other servers. As organizations navigate modernization challenges, IBM iSeries consulting has become essential for strategic guidance. Businesses increasingly rely on iSeries and AS400 managed services to bridge expertise gaps.
This piece shows how IBM's legacy system adapts while exploring modernization strategies. These strategies help businesses utilize modern technologies without compromising the platform's stability.
From System/38 to IBM Power: A Timeline of AS400 Evolution
"The pursuit of perfection means not just enthusiasm for doing a topnotch job in important things, it means attention to detail and an itch to innovate and improve in whatever we have to do." — Thomas J. Watson Jr., Former IBM CEO and son of IBM's founder
The rise of IBM's midrange computing platform stands as one of the longest-running technological experiences in enterprise computing history. This platform has managed to keep exceptional backward compatibility across four decades, from its earliest version to today's powerful systems.
System/38 and the Birth of Midrange Computing
IBM started its midrange computing experience in 1978 by introducing System/38, a revolutionary platform for business computing. The system became available in August 1979 with an object-based operating system called Control Program Facility (CPF) and featured a groundbreaking integrated relational database that later became Db2. Modern IBM i platforms still use the fundamental concepts this system introduced, such as object-based architecture and single-level storage.
IBM launched the System/36 in 1983 as a budget-friendly option for small businesses that couldn't afford System/38. System/36's simple approach and accessibility made it popular despite its lower power. Recognizing the need for a unified midrange computing strategy, IBM began integrating its diverse systems to compete more effectively with systems like Digital Equipment Corporation's VAX.
AS/400 Launch and OS/400 Integration
IBM announced the AS/400 in June 1988 and officially released it in August 1988. OS/400, the system's core operating system, supported most System/36 and System/38 applications.
OS/400 revolutionized IBM's midrange computing by introducing standardized interfaces across all models. This helped establish design principles that have now become industry expectations. The AS/400 further excelled in connectivity, letting various workstations and peripherals work together using the same interface language. This advancement extended accessibility beyond technical specialists, allowing a broader range of users to interact with IBM's systems.
The AS/400 became hugely successful, with IBM delivering nearly 500,000 systems by late 1997. Users loved its reliability, integrated database, and how it ran critical business applications without stopping.
Transition to iSeries and System i
In 2000, IBM rebranded the AS/400 as "eServer iSeries" to highlight its integration capabilities and adaptability for e-business. This shift underscored IBM's commitment to modernizing the platform for the internet era while retaining the OS/400 name for its operating system.
IBM rebranded again in 2006, calling the platform "System i" and updating the operating system name to "i5/OS" (the "5" came from POWER5 processors). This distinction set it apart from System p, which ran AIX and Linux. System i with i5/OS became an "all-in-one" Windows alternative for small and medium-sized businesses.
IBM Power Systems and IBM i 7.x Releases
In April 2008, IBM consolidated its System i and System p platforms into a unified server line called IBM Power Systems. They renamed i5/OS to IBM i, with "i" representing integration. This transition allowed IBM i, AIX, and Linux to run seamlessly on the same Power hardware, eliminating the need for separate systems.
IBM has released major versions of the IBM i operating system regularly since 2010:
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IBM i 7.1 (2010): Improved integration capabilities
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IBM i 7.2 (2014): Enhanced security, cloud integration, and analytics
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IBM i 7.3 (2016): Improved open-source technologies support
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IBM i 7.4 (2019): Added AI and machine learning integration
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IBM i 7.5 (2022): Enhanced security with support until 2030 and beyond
With the release of IBM i 7.1, IBM transitioned from traditional Modification releases to Technology Refreshes. These optional PTFs (Program Temporary Fixes) add new features without full system upgrades. Organizations can now get new capabilities while keeping their systems stable.
IBM Power Systems continue to grow with new processor generations that support both POWER9 and POWER10 hardware. IBM iSeries consulting services help organizations utilize these advancements while maintaining business continuity.
Organizations depend on iSeries managed services and AS400 managed services to bridge expertise gaps, keeping IBM AS400 services essential for running business applications.
Why AS400 Still Powers Critical Business Systems
The IBM iSeries AS400 remains the backbone of critical business operations in many industries, even decades after its launch. Its longevity comes from its architectural advantages that remain relevant in modern computing.
Built-in DB2 Database and Single-Level Storage
The IBM iSeries AS400 owes much of its success to its integrated DB2 database. It provides built-in SQL capabilities without requiring separate installations. This database system handles large amounts of structured data with ease and excels at complex data analysis.
Single-level storage architecture stands out as another game-changing feature. This technology unifies memory and disk into a seamless 64-bit address space. The system's Licensed Internal Code manages physical disk drives and presents users with a single large pool of virtual storage instead of separate physical drives.
This design offers key advantages:
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Object-based access eliminates hardware addressing
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Data automatically distributes across disks for faster retrieval
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No need for disk partitioning or defragmentation
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Reduced administrative overhead
Backward Compatibility and Long-Term Stability
IBM iSeries AS400 systems can run decades-old applications on modern hardware with minimal modifications. This feature aims to protect businesses' investments in legacy software. IBM's long-term support shows their dedication to customer success.
Organizations that need high availability choose IBM i for its proven reliability. Many companies have run AS400 systems for decades without major disruptions. This robust performance comes from built-in redundancy features that minimize downtime.
Security and Uptime in High-Risk Industries
In an era of heightened cybersecurity concerns, the IBM iSeries AS400 remains a formidable defense against threats.
The platform protects data through:
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Object-level security controls
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Advanced encryption capabilities
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Role-based access management
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Comprehensive audit trails
These security features make unauthorized access difficult, which offers banks effective protection against data breaches and ransomware.
Banks, manufacturers, and insurance companies rely on IBM AS400 services because they need reliable connections, high uptime, and strong security. Banks minimize their long-term data processing and computing costs with iSeries managed services. Manufacturing companies achieve the same with AS400 managed services.
Companies can run the iSeries platform for long periods with minimal IT support. IBM iSeries consulting helps regulated industries meet HIPAA, GDPR, SOX, and PCI-DSS standards. The system's design protects data from both inside and outside threats.
How IBM i Is Adapting to the Future of IT
The IBM iSeries AS400 platform embraces state-of-the-art technologies while building upon its traditional strengths. This progressive approach helps the platform meet today's business needs.
Support for Open-Source Languages and APIs
Java is a widely supported open-source programming language by IBM iSeries AS400. Python, PHP, and Node.js are also commonly used for development. Organizations can now integrate modern development practices with traditional RPG programming on the IBM i platform.
The platform's IBM i services support multiple open-source packages. These packages range from Apache Kafka and Tomcat to Git and Python frameworks.
AI-Powered RPG Code Assistants and Automation
IBM has announced the development of the RPG Code Assistant (RPGCA), with plans to release its beta version in the second quarter of 2025. This AI-powered tool will help developers:
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Understand existing RPG code through automated explanations
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Generate new RPG functions using natural language descriptions
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Automatically create test cases for RPG code
Organizations can now hire developers without RPG expertise while preserving existing applications. This will address the growing skills gap in iSeries managed services.
Power11 and DDR5 Memory Support in 2025
Q3 2025 will mark the release of the new POWER11 processor. This advanced chipset will offer 25% more cores per processor compared to POWER10 systems. POWER11's features include improved clock speeds, DDR5 memory support through Open Memory Interface (OMI) technology, and IBM's 'Spyre' AI accelerators that optimize data-intensive tasks.
Conclusion
IBM's AS400 systems have thrived for five decades. These systems proved remarkably resilient and adaptable in a changing digital world. Throughout their development, they managed to keep their core strengths—reliability, security, and integrated database capabilities—while adopting modern technologies for today's business needs.
The platform's architectural advantages make it essential for industries where stability and security matter the most. Its built-in DB2 database and single-level storage lead the way. The exceptional backward compatibility helps organizations protect their investment in legacy applications and embrace newer technologies gradually.
IBM integrates open-source languages, cloud platforms, and DevOps tools into the IBM i ecosystem. New innovations like AI-powered RPG code assistants and POWER11 processors show IBM's steadfast dedication to keeping the platform relevant far into the future.
