The mainframe computer appears to have more lives than the proverbial cat. Pronounced dead time and again since the late 1980s when Microsoft said the future of business computing was the PC running Windows, big iron is hanging in 20 years later despite the advent of blade servers, grid computing and the dual-core microprocessor.

In the service-oriented architecture (SOA) world, the supposedly moribund mainframe keeps popping up like a Jack-in-the-Box on steroids.

The reason the mainframe will not die is a simple matter of arithmetic, explains Dave Locke, director for IBM Rational worldwide marketing strategy.