The system is opaque
Years of changes have made it hard to tell which parts are valuable and which parts should change.
SYSTEM/38 → AS/400 → IBM i
LEGACY IS NOT THE PAST. IT IS AN ASSET.
A SYSTEMS ENGINEER
WHO LOVES
IBM AS/400
Repair legacy assets without breaking them—and carry them into the future.
“Replace it because it is old” is not a strategy. Neither is “never touch it because it still runs.”
I identify the value built into IBM i systems and help shape their next practical step.
01READUnderstand the assets
02REPAIRImprove without disruption
03BRIDGEConnect to the future
00 / IDEA
Rip-and-replace is not the only kind of DX. Building on what already works is also digital transformation.
A complete rebuild is right for some organizations. For others, preserving the business knowledge already embedded in their systems—and improving the right parts first—is faster, safer, and more rational.
BEFORE REPLACEMENT
Does that AS/400 really have to be thrown away?
Companies are often told, “AS/400 is old. Move to an open system.” Sometimes that is the right answer. But when migration itself becomes the goal, years of refined business logic may be rebuilt at enormous cost—with no guarantee that the work will become better.
The knowledge is not being passed on
Fewer engineers can read RPG, so even necessary changes begin to feel unsafe.
The future looks binary
“Leave everything alone” or “replace everything” are not the only choices.
HISTORY ≠ OBSOLESCENCE
The AS/400 is old.
So is Ferrari.
Ferrari has a long history, but it does not keep building yesterday’s cars unchanged. It preserves what matters while continually advancing performance, safety, and control technology.
The IBM AS/400 followed the same principle. The product introduced in 1988 did not stand still; its hardware, operating system, database, and development environment evolved into today’s IBM i.
1988AS/400
iSeries / System i
TODAYIBM i
A long history≠An obsolete product
The real question is not when it was born, but what it does today, what value it holds, and how it can keep evolving.
FACT SOURCE IBM | The AS/400
ONE INTEGRATED PLATFORM
IBM i is not a collection of unrelated parts.
IBM designs and delivers the processor, operating system, database, and development and operations environment as one platform.
Instead of assembling independent components and continually testing their compatibility, IBM i is designed to work as an integrated whole. That integration is one reason organizations can rely on it for decades.
FACT SOURCE IBM | IBM i/IBM | Db2 for i
BUSINESS VALUEMore company-specific toward the top
05Business logic and existing assetsYOUR KNOW-HOW
04Development and operationsRPG / TOOLS / APIs
03Db2 for iDATABASE
02IBM iOPERATING SYSTEM
01IBM PowerPROCESSOR / HARDWARE
Designed and delivered as one IBM platform
MAKE THE MOST OF IT
Preserve. Repair. Connect.
Protecting a system and changing it are not opposites. Preserve today’s value while identifying what truly needs to evolve.
01
UNDERSTAND
First, read it.
Source code, databases, screens, reports, and operations: discover the real specification from the working system, not from documents alone.
02
IMPROVE
Repair without breaking.
Understand the impact, verify the behavior, and keep the workplace running. Small changes can produce very large results.
03
CONNECT
Build the bridge forward.
Free-Form RPG, external integration, and AI: connect proven assets to new technology and the next generation of engineers.
WHAT I WORK WITH
Technology is not the goal. But the right technology makes the goal possible.
I understand IBM i from the inside and connect it to technologies outside the platform. The work starts with a real operational problem.
RPG
RPG III, RPG IV, and ILE. I read the intent of long-lived code and change it safely for today’s requirements.
Db2 for i
I improve correctness and performance by understanding data structures and access paths, including SQL and logical files.
IBM i
Jobs, objects, libraries, security, and operations—problems are considered across the whole platform.
Legacy analysis and repair
I uncover specifications and impact areas inside complex source and improve the system without stopping the business.
Free-Form RPG
Modernization is not cosmetic rewriting. It should make the code maintainable and understandable to the next engineer.
Process improvement
Manual work, waiting, transcription, and repeated checks: I turn “that is just how it is” into a solvable problem.
DX
DX is measured by whether the work actually improves—not by whether a new product was purchased.
Applied AI
I treat AI as a practical tool for research, analysis, verification, and documentation—not as magic.
ABOUT THE ENGINEER
For forty years, I have watched what must remain—and what must change.
From System/38 to AS/400 and IBM i. Names and coding styles change, but the essentials do not: understand the business, make it run correctly, and support the people who use it.
I neither chase every new technology nor cling to old technology. I respect why a system has lasted, then keep looking for a better way forward.
SELECTED RESULTS
2 million records10 sec → under 1 sec
Extracted about 100 orders through complex business logic after redesigning the data access path.400 million recordsAbout 30 min → 20–30 sec
Rebuilt a condition-addition process that created new records when complex criteria were met.2–3 hours → about 10 secondsAutomated the verification of database updates.
I can read old IBM i assets.
I can repair them without breaking them.
And I can bridge them to Free-Form RPG.
NOTES FROM THE FIELD
Stories from the workplace—and from IBM i.
Technology alone does not tell the whole story. These are real experiences: successes, mistakes, unexpected discoveries, and a little laughter.
We Showed White Blood Cells to AI.
The Future Was Already There.
In November 2019, we completed a white-blood-cell morphology classification PoC using IBM PowerAI Vision. Specialists saw its potential, but it never reached production. Old blog entries and public records now tell the fuller story.
The AS/400 Wasn’t Slow.
Don’t Make It Work 12 Billion Times.
It read about 400 million records and looked up master data dozens of times for each one—yet the AS/400 still finished in 30 minutes. Redesigning the data access cut that to 20–30 seconds.
SYSTEMS SHOULD AGE WELL.
Carry IBM i
into the next generation.
Read before discarding. Understand the value before changing.
Make today’s assets a foundation for the future—not an obstacle to it.
Yoshiochin.com will keep growing from here.