Heirloom Computing

Signs, Theories, and the Paradox of Legacy Code Translation

Why translating code is really about reconstructing lost theories — Graham Cunningham, CTO

Introduction

You’d think translating COBOL to Java would be easy. They’re both programming languages, right? Just map the syntax and you’re done.

But if you’ve ever tried it, you know the truth: the hard part isn’t the language, it’s the meaning. Those COBOL programs aren’t just instructions for computers. They’re theories about how to run a business, encoded in ancient runes that few understand.

When you’re translating legacy code, you’re not just converting syntax. You’re trying to reconstruct the theories in the original programmers’ heads. And those theories exist nowhere in the code itself.

The Three Brains Problem

I was thinking about this in the context of AI-assisted translation systems. These systems usually have three components that mirror the three systems in the human brain:

1. The Chimp: a large language model that does rapid pattern matching, like our instinctive brain.

2. The Human: a server that parses code slowly and carefully, like our deliberative reasoning.

3. The Computer: a database of previous translations, like our stored knowledge.

What we need is a way to orchestrate these systems to work together, just like our three brains do.

Semiotics and the Theory-Building Challenge

I had a breakthrough when I started thinking about this in terms of semiotics. Programming languages are sign systems. But signs aren’t meanings. The same COBOL statement can mean different things in different contexts.

What matters is the interpretant, the implicit theory that links signs to meanings. In human communication, interpretants come from shared context. In legacy code, they come from the business logic in the programmer’s head.

So the real challenge in legacy translation isn’t converting signs. It’s reconstructing theories. You have to infer the original programmer’s intentions from artifacts, the code they left behind.

This is a fundamentally different kind of problem from what most AI tackles. It’s not about finding patterns in data. It’s about finding theories in artifacts.

Why This Is Hard

Theory reconstruction is hard because most of the context is lost. The original programmers are gone. The documentation is outdated. The business has changed. You’re left with code that works, but no one knows why.

Most translation projects fail because they focus on syntax and ignore semantics. They generate Java that compiles but doesn’t capture the business logic. Then, six months later, someone needs to modify it and realizes the theory is gone.

The key insight is that we need to teach machines to do what humans do when we read code. We use rapid pattern matching to get oriented, slow, careful analysis to understand logic, and stored knowledge to infer intentions.

Forging A Way Forward

If we can architect translation systems around this insight, if we can build interpretant-reconstructing machines, then we have a shot at solving the legacy code problem for real.

In the next article, we’ll explore how these theoretical insights translate into practice through a deeper examination of the mental models that guide human code comprehension—and how we can teach machines to think the same way.

It’s not just about translating languages. It’s about translating theories. That’s a much more interesting challenge. And the potential impact is enormous.

But it’s going to take a fundamentally different approach than what the industry is doing today.

Semiotics—The Fourth Dimension of Mainframe Modernization

Why mainframe modernization is so hard (and so worth it) — Graham Cunningham, CTO

There’s something strange about mainframe modernization projects. On paper, they should work. You have the technical skills. You understand the business processes. Your team is aligned and committed. Yet a lot of these projects fail to deliver the expected value, if they work at all. 

I’ve been in the middle of complex modernization projects for over twenty years, and I’m publishing this series of articles to share some insights that I’ve distilled along the way.

Over a series of articles, I will show how our customers reduce costs, reduce risk, increase speed, solve the skills shortage, and end up with their applications running on a modern stack—the holy grail of mainframe modernization. But let’s start with the key insight. 

Everyone talks about the three dimensions of modernization challenge: technical (migrating code and data), operational (preserving processes), and cultural (managing people). But there’s a fourth dimension that almost no one sees until it’s too late. 

The fourth dimension is semiotic.

Semiotics is the study of meaning—how signs and symbols carry information beyond their literal content. It turns out that forty-year-old mainframe systems are packed with meaning that isn’t in the code.

Think about it this way. Your grandmother’s recipe for apple pie says, “bake at 350 degrees.” But it doesn’t tell you that she always knew her oven ran hot, or that through decades of real-world experience, she could tell by smell & touch when it was done, or what to do when the humidity made the dough sticky. That knowledge lived in her head, not on the recipe card. 

Mainframe systems have the same characteristics. They contain decades of accumulated wisdom about edge cases, regulatory requirements, and operational realities that someone learned the hard way. This wisdom isn’t documented—it’s embedded in the code patterns, error handling approaches, and design decisions. 

When you migrate a system, you can copy the logic. But can you copy the wisdom? 

Modernization today treats code like a foreign language that needs word-for-word translation. COBOL becomes Java. CICS becomes microservices. DB2 becomes PostgreSQL. But this is like translating poetry with Google Translate. You get the words, but you lose the soul. 

The companies that succeed at mainframe modernization—really succeed, not just technically but operationally—figure out how to preserve the institutional theories embedded in their legacy systems. They understand that these systems aren’t just functional specifications. They’re repositories of competitive intelligence. 

A forty-year-old banking system doesn’t just process transactions. It embodies learned responses to every weird edge case that can happen in banking: leap years that fall on bank holidays, customers who try to withdraw money at exactly midnight on New Year’s Eve in 1999, and so on.

The solution isn’t simply better documentation or more comprehensive testing, because you will never think of all the edge cases. It’s understanding that migration is really about translating meaning, not just code. It’s about preserving the institutional theories that made your systems reliable, not just making them run on modern infrastructure. 

Once you see the fourth dimension, everything else makes sense. The projects that succeed aren’t just about moving code—they’re about preserving an essential competitive advantage. Many of the ones that fail are undermined by the accidental loss of decades of accumulated wisdom. 

The question isn’t whether to modernize your mainframe systems; the question is how to do it effectively and in a way that preserves their intelligence.

Leadership Excellence. Cloud Migration Visionary.

Heirloom Computing—recognized as a pioneer for IBM Mainframe Modernization.

“Heirloom is setting new standards in cloud migration, earning Gary the prestigious title of Cloud Migration CEO of the Year 2024.”

Heirloom Computing Named a Leader in the ISG Provider Lens™ Mainframe Services & Solutions U.S. 2025 Quadrant Report Copy

Heirloom® recognized as Leader for Mainframe Application Modernization Software.

Information Services Group (ISG), a well-known technology research and advisory firm renowned for its industry and technology expertise, has named Heirloom Computing a Leader in its Mainframe Services & Solutions U.S. 2025 Quadrant Report.

“Heirloom Computing’s toolset offers rapid transformations with precise results. It has added GenAI capabilities to enhance speed and quality, delivering clean Java code that is easy to improve and maintain.” – Pedro L. Bicudo Maschio, Distinguished Analyst and Executive Advisor, ISG

Companies that receive the Leader award have a comprehensive product and service offering, a strong market presence, and an established competitive position. The product portfolios and competitive strategies of Leaders are strongly positioned to win business in the markets covered by the study. The Leaders also represent innovative strength and competitive stability.

Enterprises with IBM mainframes are increasingly looking to modernize their mainframe ecosystem. Increasing costs, decreasing skills, and a need to make application workloads more agile are driving the modernization wave. Heirloom migrates mainframe workloads using compiler-based refactoring to produce cloud-native applications that run on any platform.

Highlights from the report:

“Heirloom Computing offers a differentiated replatforming and refactoring technology renowned for its rapid processing of large code bases. It generates native Java applications that run on any cloud, enabling clients to retain source code in COBOL/PL1 or Java.”

Heirloom Computing Named as the IBM Mainframe Migration Solution Company of the Year by CIOReview

Heirloom® h/GENAI™ — Transforming Mainframes for a Future-Ready World.

“We put the reins [of IBM Mainframe Modernization] in the hands of our customers.” – Becky Etheridge, Chief Partner Officer

Heirloom Computing Named a Leader in the ISG Provider Lens™ Mainframe Services & Solutions U.S. 2024 Quadrant Report

Heirloom® recognized as Leader for Mainframe Application Modernization Software.

Information Services Group (ISG), a well-known technology research and advisory firm renowned for its industry and technology expertise, has named Heirloom Computing a Leader in its Mainframe Services & Solutions U.S. 2024 Quadrant Report.

“Heirloom has rapidly gained market share by offering a fast modernization option to handle large applications. It offers the flexibility to choose between replatforming or refactoring applications, offering clients greater control over their modernization journey.” – Pedro L. Bicudo Maschio, Distinguished Analyst and Executive Advisor, ISG

Companies that receive the Leader award have a comprehensive product and service offering, a strong market presence, and an established competitive position. The product portfolios and competitive strategies of Leaders are strongly positioned to win business in the markets covered by the study. The Leaders also represent innovative strength and competitive stability.

Enterprises with IBM mainframes are increasingly looking to modernize their mainframe ecosystem. Increasing costs, decreasing skills, and a need to make application workloads more agile are driving the modernization wave. Heirloom migrates mainframe workloads using compiler-based refactoring to produce cloud-native applications that run on any platform.

Highlights from the report:

“Heirloom Computing offers a differentiated replatforming and refactoring technology renowned for its rapid processing of large code bases. It generates native Java applications that run on any cloud, enabling clients to retain source code in COBOL/PL1 or Java.”