IBM has threatened mainframe emulator TurboHercules with a lawsuit for allegedly violating its patents, raising the question of whether it has broken its vow not to assert IP rights against open-source developers.

TurboHercules sells an implementation of the open-source Hercules System/370, ESA/390, and z/Architecture Emulator, which is available under the Q Public License.

In a March 11 letter to TurboHercules, Mark Anzani, vice president and CTO of IBM System z, sent TurboHercules a non-exhaustive list of the patents that it believes the Hercules software violates. The letter referenced IBM’s lawsuit against Platform Solutions Inc., which produced a mainframe emulation system.

TurboHercules responded by filing an antitrust complaint against IBM with the European Commission in Brussels.

“We were merely responding to TurboHercules’ surprise that IBM had intellectual property rights on a platform we’ve been developing for more than 40 years,” explained IBM spokesperson Steve Eisenstadt. He added that IBM will stand by its 2005 pledge, but will also assert its rights to protect significant investments in mainframe technology.

IBM announced open access to 500 of its patents in 2005 to establish a “patent commons” for individuals and groups working on open-source software. IBM has serious questions about whether TurboHercules qualifies, Eisenstadt said, citing its participation in industry organizations founded and funded by IBM competitors such as Microsoft “to attack the mainframe.”

Those organizations include, an online forum about creating an open market for IBM-compatible mainframe solutions, and the Computer & Communications Industry Association (CCIA). Microsoft is a sponsor of, and was actively involved in its creation. CCIA is a Washington D.C.-based organization that advocates for open systems and “fair competition.” Its members include AMD, Google, Microsoft, Oracle and Yahoo.

Likewise, TurboHercules is accusing IBM of acting in bad faith by choosing to embrace Linux, which helps it pursue business goals, while attacking open-source software that competes against its mainframe products, TurboHercules cofounder Roger Bowler wrote in a blog entry on the company’s website.

“IBM says that TurboHercules seeks a free ride on IBM’s ‘massive investments in the mainframe by marketing systems that attempt to mimic the functionality’ of its machines,” wrote Bowler. “By the same logic, one might very well charge that Linux is nothing more than an attempt to ‘mimic’ the functionality of Unix.

“Suppliers of Unix systems such as IBM, HP and Sun have undoubtedly invested large sums over many years in developing these platforms. Is it therefore wrong for Red Hat and SUSE to offer users a less expensive ‘Unix-like’ operating system that has the conspicuous advantage of being open-source and of being able to run on just about any server the user pleases?”

Hercules was never positioned as an IBM-brand name product, and customers would not mistake it as such, Bowler said. “Hercules is a third-party, open-source software-based emulator developed in good faith using IBM’s published documentation of its z/Architecture.”