Why Your AS/400 Doesn't Need to Be Replaced — Just Connected

The IBM AS/400 — now known as IBM i or iSeries — is one of the most reliable computing platforms ever built. Some AS/400 systems have been running continuously for over 25 years, processing critical business transactions without interruption. If your organisation runs one, you already know this: it works, and it works well.

The problem isn't the machine. It's the isolation. Your AS/400 is an island — a self-contained system that does its job brilliantly but doesn't easily share its data with modern tools, analytics platforms, or AI assistants. And the pool of people who can develop for it is shrinking every year.

The Case Against Replacement

Full AS/400 replacement projects are notoriously risky. The business logic embedded in RPG programs and CL scripts has been refined over decades. It handles edge cases that nobody remembers creating solutions for. Replacing it means understanding every one of those edge cases and rebuilding them in a new system — and the cost of getting one wrong can be significant.

Many AS/400 replacement projects run over budget, over time, and some fail entirely, leaving the organisation worse off than when they started. The platform itself isn't the problem that needs solving.

Connection Instead of Replacement

The alternative is to keep the AS/400 running and build modern integration layers on top of it. An MCP server can connect to your AS/400's DB2 database, reading data in real time and making it accessible to AI assistants, modern web applications, and analytics tools.

This approach preserves everything that works about your AS/400 while eliminating its biggest limitation: data isolation. Your executives can query AS/400 data using plain English. Modern applications can read from and write to AS/400 through standard APIs. AI can analyse decades of transactional data for patterns and insights.

Practical Benefits

Connecting your AS/400 to AI delivers immediate benefits. Natural-language queries replace green-screen navigation — ask "What's the current stock level for part number X?" instead of navigating through menu screens. Cross-system analysis becomes possible — combine AS/400 data with data from other systems for a complete business picture. Automated reporting draws directly from AS/400 data without manual extraction. And new team members can access business data without needing to learn the AS/400 interface.

The Gradual Path

Connecting your AS/400 also creates a natural pathway to eventual modernisation if and when you choose it. With the integration layer in place, you can migrate individual functions off the AS/400 one at a time, testing each migration against the AI-mapped business logic before cutting over. There's no big-bang risk. Each function can be migrated independently, validated, and rolled back if needed.

Getting Started

A discovery audit examines your AS/400 environment — its database structure, the applications running on it, and the business processes it supports. From there, the audit recommends the most practical integration points and maps out a build plan that starts delivering value within weeks, not months.