Microsoft Chairman Bill Gates and CEO Steve Ballmer revealed on Tuesday a few details on the software company’s next operating system, Windows 7, at the D: All Things Digital conference in San Diego. The company has maintained a disciplined silence about the upcoming OS — a marked contrast to the constantly changing plethora of information released during the five years it took Microsoft to develop and launch Windows Vista. During their keynote address, Gates and Ballmer presented a demonstration of the multitouch user interface the software maker plans to add to the OS.