Microsoft Co. and Nihon Unisys Ltd. will jointly construct banking systems based on personal computer servers running the Microsoft Windows operating system, sources said Monday.

The planned systems will be the first of their kind in the global banking industry. Proprietary software and the Unix-based OS are more common, and no banking system has ever been built entirely around Windows, industry observers said.

The two companies will announce the tieup Tuesday, the sources said. Microsoft Co. is the Japanese arm of U.S. software giant Microsoft Corp.

They have already received an order from Hyakugo Bank, a regional lender based in Mie Prefecture, for a system to be up and running in 2007, the sources said.

Large replacement demand is expected as many banks, which now operate mainframes running proprietary software, are expected to update their systems.