IT Management

In the April/May 2007 issue of z/Journal, the article “The State of IBM Mainframe Emulation” detailed several software emulation approaches for smaller IBM mainframe customers. These products let customers run existing mainframe operating systems and applications on non-mainframe hardware.

The article also discussed some ongoing legal actions surrounding these offerings. These issues meant that the mainframe emulation world was in a state of flux, with accompanying Fear, Uncertainty and Doubt (FUD) for smaller mainframe customers.

This article provides an update on these products. Significant events have transpired, with a mix of good news, bad news, and the unknown.


At the time the original article was written, three emulation options were in use in various shops: Open Mainframe, from Platform Solutions, Inc. (PSI); FLEX-ES, from Fundamental Software, Inc.; and Hercules, which is an open source package.

The PSI product didn’t fully implement the mainframe architecture, but provided enough functionality to run IBM’s flagship z/OS operating system. However, PSI was crippled from the start by IBM’s unwillingness to license z/OS for PSI machines. A handful of PSI customers managed to transfer licenses from existing machines, but IBM blocked that loophole. IBM next sued PSI for what it claimed to be a violation of intellectual property agreements and for encouraging violation of its licensing agreements. PSI countersued, claiming unfair and monopolistic business practices by IBM. For more than a year, prospective PSI customers watched from afar, many unwilling to bet on a tiny company against the IBM juggernaut.

The PSI action also affected Fundamental and existing FLEX-ES customers. Due to the PSI legal proceedings, IBM declined to renew its patent licensing with Fundamental. This made unpleasant sense: IBM wanted to keep PSI from arguing that if IBM was licensing its intellectual property to Fundamental, it must do the same for PSI.

Unfortunately, the fallout from these non-technical events meant that Fundamental had to stop selling new FLEX-ES licenses. Worse, many IBM PartnerWorld shops—the small, independent software vendors for System z—had FLEX-ES systems, which were acquired through PartnerWorld at a significant discount. These machines had a three-year expiration date, enforced through a hardware dongle. The dongles on so-called “commercial” FLEX-ES systems don’t expire, but these systems are only 31-bit (PartnerWorld machines were full 64-bit z/Architecture).

Hercules, while reasonably robust (albeit significantly slower than FLEXES) and offering 64-bit functionality (although with no guarantee of full z/Architecture function or compatibility), had the same Achilles’ heel as PSI: IBM was unwilling to license products for use on Hercules machines.

After more than a year and a half of filings, counter-filings, and counter-counter-filings, IBM made most of the PSI issue moot on June 30, 2008, by acquiring the company outright. While, initially, this might seem nonsensical, it was anything but. First, IBM had been hoping PSI would run out of money and fold the tent. Instead, Microsoft made a minority investment; presumably the prospect of Microsoft’s bottomless coffers derailed the “wait ’em out” strategy. In addition, while IBM was confident its position would prevail in court, a prolonged legal battle was unlikely to be productive. Instead, IBM allegedly went directly to most PSI stockholders and made an offer, which was accepted. This ends the IBM-PSI lawsuits, although some EU legal actions and a suit by a former IBM business partner are still pending.

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