RI-DOS

RI-DOS (an acronym for Radiantelligence Disk Operating System) is an operating system for x86-based personal computers mostly developed by Radiantelligence. Released on July 1989, it became one of the first commercially viable alternatives to MS-DOS. It was developed by Jack Nicholson, and his friend, Tony Wile.

Today, RI-DOS faded into obscurity due to the popularity of OpenRadiantOS, Radiantelligence's main operating system since 1996.