The IBM AS400, now known as IBM i, represents one of the most resilient and enduring enterprise computing systems in history. Introduced by IBM in 1988, it was engineered to provide a comprehensive solution for midrange computing needs, combining hardware and software into a single integrated platform. Businesses across sectors such as banking, healthcare, manufacturing, and logistics have relied on this platform for decades to run mission-critical applications. Despite numerous shifts in technology paradigms, including the emergence of cloud computing and distributed systems, IBM AS400 has managed to remain relevant through continuous innovation and modernization. Its core strengths lie in unmatched stability, high performance, integrated database capabilities, and powerful security features.
The system’s backward compatibility ensures that decades-old applications can still run on the latest hardware, making it an invaluable asset to organizations with complex legacy systems. While some may see it as a relic of the past, IBM AS400 has evolved with time—offering support for modern programming languages, APIs, and integration with cloud environments. It remains a trusted platform, quietly powering some of the most crucial business operations worldwide.
This blog by Multisoft Systems dives deep into what IBM AS400 online training is as well as it’s architecture, features, evolution, and role in today’s digital enterprise environment.
What is IBM AS400?
IBM AS400, or Application System/400, is a midrange computer system developed by IBM for small to medium-sized enterprises and departments of larger corporations. It was designed to consolidate data management, application development, and system operations into a single platform. Initially introduced in 1988, it has undergone numerous transformations but has consistently maintained its reputation for reliability, security, and scalability. Today, the system operates under the name IBM i, running on IBM Power Systems hardware, but the term “AS400” is still widely used across industries.
The defining characteristic of the AS400 is its integrated architecture. It features an object-based operating system (OS/400, now IBM i), a built-in DB2 database, and supports multiple programming languages including RPG, COBOL, Java, and CL. The single-level storage concept of AS400 certification treats memory and disk as one, simplifying data management and boosting system efficiency. Another unique feature is its tight coupling of hardware and software, which results in a highly optimized and stable computing environment.
AS400 is commonly used for enterprise resource planning (ERP), customer relationship management (CRM), financial systems, and other mission-critical business applications. It is especially favored in industries requiring consistent uptime, strong data integrity, and comprehensive security. In the era of digital transformation, AS400 continues to play a significant role, offering seamless integration with web services, cloud platforms, and modern APIs. Its continued evolution proves that AS400 is not just a legacy system, but a future-ready platform capable of adapting to modern business needs.
The History of IBM AS400
The IBM AS400 was born from IBM’s need to unify its System/36 and System/38 lines into one versatile platform. Officially launched in June 1988, AS400 revolutionized midrange computing by offering a fully integrated system with unparalleled security, stability, and data handling capabilities. Over the decades, IBM made several rebranding and technological upgrades to ensure the AS400 platform remained current with industry demands:
- 1988: IBM launches AS/400, combining features of System/36 and System/38.
- 1994: Introduction of the AS/400 Advanced Series with better processing capabilities.
- 2000: Rebranded to IBM iSeries as part of IBM’s eServer line.
- 2006: Became IBM System i to align with System p under IBM Power Systems.
- 2008: Integrated into IBM Power Systems platform; OS/400 rebranded as IBM i.
- 2010s-Present: Continuous modernization with support for open-source languages, cloud integration, and web services.
Despite these changes, the AS400's core philosophy—robust performance, integration, and reliability—has remained unchanged.
Hardware Architecture
The hardware architecture of IBM AS400 is centered on the principles of simplicity, integration, and fault tolerance. Originally built on a proprietary CISC (Complex Instruction Set Computer) processor, it later transitioned to RISC (Reduced Instruction Set Computer) architecture with the PowerPC-based processors to enhance performance. Modern iterations now run on IBM Power Systems using the POWER processors. The architecture supports single-level storage, meaning disk and memory are addressed within the same space, which simplifies programming and resource management. The system is designed with redundancy in mind—offering features like mirrored disk arrays and hot-swappable components to ensure high availability. This makes the AS400 training particularly well-suited for industries that require continuous uptime and robust data integrity. The system supports a range of peripherals including terminals, printers, and networking devices, all managed through integrated device drivers, minimizing compatibility issues. The integrated nature of hardware and software ensures optimal performance and reliability, making IBM AS400 hardware architecture a cornerstone of enterprise-grade computing.
Software and Operating System (OS/400 & IBM i)
The operating system originally called OS/400 and now known as IBM i is the heart of the AS400 system. Unlike traditional operating systems, IBM i is object-based, meaning every entity (such as files, programs, and users) is treated as an object, enhancing security and system integrity. It includes a built-in relational database (DB2 for i) that is deeply integrated into the OS, eliminating the need for external database management systems. The OS offers features such as job scheduling, security, backups, and system administration tools out-of-the-box. IBM i supports both green-screen terminal access and modern GUI-based interfaces, along with web and mobile application access. It includes Command Language (CL) for automation and scripting, and can also run Java-based applications natively.
Modern IBM i systems are cloud-compatible and support virtualization, making it possible to host multiple logical partitions (LPARs) on the same physical hardware. IBM continuously enhances IBM i with security patches, performance updates, and support for contemporary programming languages like Python, PHP, and Node.js. The OS/400 to IBM i evolution reflects IBM’s commitment to adapting the platform to the needs of today’s IT landscape.
Programming Languages in AS400
IBM AS400 supports a rich variety of programming languages, enabling developers to build, maintain, and modernize applications across decades. The most historically significant language is RPG (Report Program Generator), which has evolved over time into RPG IV and Free-format RPG, maintaining backward compatibility while incorporating modern syntax. Alongside RPG, COBOL remains widely used, particularly in finance and insurance sectors where legacy applications dominate. CL (Control Language) scripts are essential for system automation and batch processing. The AS400 also supports SQL, tightly integrated with the native DB2 database, allowing powerful data manipulation capabilities. In recent years, IBM has expanded support to include Java, making the system more versatile for web-based and object-oriented applications. Furthermore, with the growing demand for open-source development, IBM i now accommodates Python, PHP, and Node.js, making it possible to integrate modern web services and APIs. This broad language support ensures that IBM AS400 remains both backward-compatible and forward-looking, catering to traditional enterprise needs while enabling digital transformation initiatives.
Key Features of IBM AS400
- Integrated DB2 database for seamless data handling
- Object-based operating system for enhanced security
- Single-level storage simplifies memory and disk management
- Exceptional backward compatibility for legacy applications
- Native support for multiple programming languages
- Built-in job scheduling and resource allocation
- Advanced security and auditing features
- Scalability from small businesses to large enterprises
- High availability and fault-tolerant hardware
- Cloud and virtualization support with IBM Power Systems
- Modern GUI interfaces along with green screen terminals
- Continuous updates and long-term IBM support
Benefits of Using IBM AS400
- Reliability: Known for uptime and stability—ideal for mission-critical systems
- Scalability: Easily scales with growing business demands
- Security: Built-in encryption, access controls, and audit trails
- Cost-Efficiency: Long hardware lifecycle and low total cost of ownership
- Performance: Optimized for high-throughput transaction processing
- Integration: Easy integration with APIs, cloud, and third-party software
- Backward Compatibility: Protects investment in legacy applications
- Maintenance: Lower need for frequent patches and updates
- Versatility: Supports legacy and modern development environments
- Support: Strong vendor and community support with regular enhancements
Conclusion
IBM AS400, now known as IBM i, continues to be a cornerstone of enterprise IT infrastructure thanks to its unmatched reliability, scalability, and integrated design. Despite being decades old, the platform has evolved with modern technologies—supporting open-source languages, cloud integration, and advanced security features. Its ability to run legacy applications while supporting new ones makes it a valuable asset for businesses navigating digital transformation.
As organizations seek robust and secure systems for mission-critical operations, IBM AS400 proves that true innovation is not always about what's new, but what stands the test of time and continues to deliver consistent value. Enroll in Multisoft Systems now!