A Guatemalan inventor claims Microsoft is illegally using his software to transfer information between its spreadsheet products Excel and Access.
Carlos Armando Amado says he filed a patent in 1990 for software which lets users move data between Excel to Access via a spreadsheet. He tried to sell it to Microsoft two years later, according to Reuters.
Amado claims Microsoft started using his technology in Access releases from 1995 to 2002. Microsoft deny this saying they started working on the technology in 1989 - three years before Amado came to see them.
The suit does not claim specific damages but lawyers told Reuters they would be asking for about $2 for every copy of the software sold, which equates to $500m. The case is being heard in the US District Court of Central California.
Microsoft is also facing patent claims over Longhorn, the next version of Windows, from networking company Alacritech. It is also being sued by Forgent Networks which claims the software giant broke its JPEG picture compression patents.
