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Blog Post
How watsonx Code Assistant for Z compares to traditional manual code analysis
Modernizing mainframe applications the easy way with watsonx Code Assistant for Z
As an AI engineer working hands-on with mainframe modernization, I’ve seen how challenging and painstaking it is to analyse legacy COBOL systems. Decades-old code, missing documentation, and SME dependencies make understanding business logic a time consuming ordeal. Traditional methods rely heavily on tribal knowledge, countless hours of manual tracing, and deep COBOL expertise.
With application modernization becoming a strategic priority, these manual methods are no longer scalable or sustainable. That’s where IBM watsonx Code Assistant for Z steps in.
In this blog post, I’ll walk you through how watsonx Code Assistant for Z compares to traditional COBOL analysis, based on real-world engagements and POCs. This isn’t theory; it’s a practitioner’s view on where watsonx Code Assistant wins and why it matters.
Traditional COBOL code analysis – The old way
In the traditional world, COBOL analysis means:
- Reading code line by line
- Tracing PERFORM statements across deeply nested paragraphs
- Decoding COPYBOOKS
- Relying heavily on SME memory or tribal knowledge
We’ve all been there with sticky notes, Excel trackers, and long whiteboarding sessions just to figure out what a single program is doing.
This method works… but it’s slow, resource-intensive, and doesn’t scale. With thousands of modules in a typical legacy estate, each new program feels like reinventing the wheel.
Here are the common struggles we’ve all faced:
- Tracing logic across copybooks and programs
- Sparse or missing documentation
- High risk of misinterpretation especially when original developers have retired
- Cognitive overload when tracking nested and interdependent logic
- Massive time and cost investments
The watsonx Code Assistant for Z Advantage – How it changes the game
Now imagine uploading your COBOL modules into a system that explains the logic clearly, in plain English.
That’s exactly what watsonx Code Assistant for Z does. Using generative AI, it reads and interprets COBOL code, providing clear explanations, extracting business rules, identifying validations, and visualizing data and control flows. It’s not just a tool; it’s an accelerator for modernization and knowledge transfer.
One of the biggest benefits I’ve witnessed is a reduced dependency on legacy SMEs. Even junior developers can onboard faster, and senior COBOL experts can focus on strategic decisions rather than basic deciphering.
Here’s what stood out to me in day-to-day usage of watsonx Code Assistant for Z:
- It can explain COBOL logic in clear, structured English
- It provides data traceability
- It can extract business rules for accurate test generation
- It can visualize data and control flow that is critical for understanding file processing and edits
- It can generate live documentation that stays aligned with the code
Learn more about watsonx Code Assistant for Z can do in the documentation.
A side-by-side comparison
| Aspect | Manual analysis | watsonx Code Assistant for Z |
|---|---|---|
| Time to understand the logic | Weeks | Hours or less |
| Documentation | Sparse or outdated | Auto generated and accurate |
| Business rule extraction | Manual, often error prone | Structured and traceable |
| SME dependency | High | Significantly reduced |
| Onboarding new developers | Long ramp-up time | Faster, more efficient |
Real world story: watsonx Code Assistant for Z in action
One of the standout modernization use cases came from a leading Fortune 500 financial services company which approached modernization with a mix of urgency and scale. Their core systems were built on a massive COBOL codebase, accumulated over decades, and spread across hundreds of interdependent modules. But that was just part of the challenge.
In addition to COBOL, they were running Assembler programs that were critical to their business workflows, many of which had limited documentation and were understood only by a handful of SMEs. To add to the complexity, they had significant COBOL-Java interoperability, with business logic split across mainframe and distributed environments. Understanding and maintaining such a hybrid system required tribal knowledge and intensive manual tracing.
By applying watsonx Code Assistant, our client was able to:
- Automatically extract business purpose and validation logic from COBOL and Assembler code.
- Visualize code dependencies and data flows across modules, even those interfacing with Java systems.
- Enable both legacy and new developers to understand the logic without relying on retiring SMEs.
- Accelerate modernization to Java by generating human readable documentation from legacy code.
Why this matters more than ever
Modernization starts with understanding. And that’s exactly where most legacy projects struggle, with a lack of clarity on what the code actually does.
IBM watsonx Code Assistant for Z bridges this gap. It unlocks business logic, accelerates onboarding, reduces risk, and helps organizations move from legacy to modern with clarity and control.
For companies battling SME attrition, regulatory pressures, or aggressive modernization timelines, watsonx Code Assistant for Z is no longer optional, but strategic.
That said, human insight remains irreplaceable. IBM watsonx Code Assistant for Z doesn’t replace SMEs, but enhances their reach, accuracy, and impact.
Want to learn more? Read the article, Accelerate Mainframe DevOps with AI driven refactoring and testing, to learn how watsonx Code Assistant for Z helps simplify code transformation and automate testing in Mainframe DevOps workflows.