"What was most impressive was how well it worked and how powerful it was," Rymarczyk says. "It let you provide test platforms for software testing and development so that now all of that activity could be done so much more efficiently. It could be interactive too. You could be running a test operating system. When it failed you could look in virtual memory at exactly what was happening. It made debugging and testing much more effective."

IBM's first hypervisors were used internally and made available publicly in a quasi- model. Virtualization was "an internal research project, experimental engineering and design," Rymarczyk says. "It wasn't originally planned as a product."The hypervisor did become a commercially available product in 1972 with VM technology for the mainframe. But it was an important technology even before its commercial release, Rymarczyk says.

"In the late 1960s it very quickly became a critical piece of IT technology," he says. "People were using it heavily to do interactive computing, to develop programs. It was a far more productive way to do it, rather than submit batch jobs."When Rymarczyk joined IBM on a full-time basis he was working on an experimental time-sharing system, a separate project that was phased out in favor of the CP-67 code base. CP-67 was more flexible and efficient in terms of deploying VMs for all kinds of development scenarios, and for consolidating physical hardware, he says.

While Rymarczyk didn't invent virtualization, he has played a key role in advancing the technology over the past four decades. A graduate of in electrical engineering and computer science, Rymarczyk worked for IBM in Cambridge until 1974, when he transferred to the Poughkeepsie, N.Y., lab, where he stayed for two decades.

In the early 1990s, Rymarczyk helped develop Parallel Sysplex, an IBM technology that lets customers build clusters of as many as 32 mainframe systems to share workloads and ensure high availability. He was also one of the lead designers of Processor Resource/System Manger, which let users logically slice a single processor into multiple partitions.In 1994, Rymarczyk transferred to IBM's lab in Austin, Texas, as part of an effort to bring mainframe technology and expertise to IBM Power systems. This helped spur the creation of a for IBM's Power-based servers in 1999. Rymarczyk is still based in Austin, and has no plans to leave IBM.