Geoffrey Decker
Instructor, Northern Illinois University
Co-Founder and Lead Instructor, Eli Madison Memorial Apprenticeships (EMMA)
DeKalb, Illinois, USA
This piece is part of the 2026 Planet Mainframe Influential Mainframers series.
The Maestro of the Mainframe
Instructor at Northern Illinois University (NIU) and Co-Founder of Eli Madison Memorial Apprenticeship (EMMA), Geoffrey Decker has spent over 24 years in the classroom, but his journey to the heart of enterprise computing didn’t start with a code editor. It started with a baton.
From Orchestra to Assembler
Before he was a four-time IBM Champion, Geoffrey was a music major with dreams of becoming a world-class conductor. While he eventually traded the podium for the lectern, he never lost the performer’s discipline.
He often tells his students that learning a programming language is exactly like mastering an instrument: it requires hours of solitary practice, a blend of artistic intuition, and rigorous analytical depth.
“I tell my students that Assembler is the Shakespeare of programming,” Decker says. “It’s the basis of everything we do. You have to understand the ‘notes’—the bytes and the storage—to appreciate the symphony of the system.”
Building the Pipeline
At NIU, Geoffrey manages one of the most robust mainframe programs in the United States. He instructs on more than theory; he puts 40 to 60 students through a “real-world” ringer every year, covering everything from Db2 SQL to complex system linkage.
His commitment to the platform also emerges at industry conferences like SHARE and IBM TechXchange. Geoffrey is known for arriving with a “platoon” of students in tow, acting as their primary bridge to the professional world.
“One of the things I think is important to give to my students is some of that industry experience,” Decker said in a 2024 interview with Planet Mainframe. “I want to show them how important the mainframe is and what opportunities exist out there.” More than one student who attended events with Decker are now gainly employed in the mainframe sector.
“He treats his students as peers from day one,” one colleague noted. “He isn’t just teaching them JCL; he’s introducing them to their future colleagues and showing them they belong in this community.”
The EMMA Mission: Access for All
But teaching in the classroom isn’t enough. As the co-founder and lead instructor for EMMA, Decker is a tireless advocate for non-traditional learners. The EMMA program specifically targets veterans, later in life career-changers, and even unhoused individuals, providing a pathway into high-tech roles that would otherwise be inaccessible due to tuition and prerequisites.
For Geoffrey, mainframe education isn’t a gate to be kept; it’s a door to be held open. His work with EMMA is completely voluntary, fueled by a belief that the mainframe ecosystem is only as strong as its rising talent.
A Lifetime Legacy
Whether he’s serving on the governing board of the Open Mainframe Project or playing the French horn in the Kishwaukee Symphony Orchestra, Geoffrey lives by a philosophy of total contribution. He is a legendary fixture in the community because he shares his time and talent for the future.
“I’m getting close to retirement, but I’m trying to find a way to pass everything I do on to someone who comes after me. I don’t want this program to go away. The mainframe community is like no other. I’ve never met a group of people more supportive of the young, and that is what matters most.”
An influential mainframer who bridges the gap between formal education and nontraditional career paths, Geoffrey Decker ensures the engine of the world’s economy is powered by a diverse and well-trained workforce.
You can connect with Geoffrey Decker on LinkedIn.
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