OS X Yosemite, Apple's operating software for Macintosh computers, is the eleventh release of OS X. OS X Yosemite, which was first announced and presented to developers at WWDC 2014 on June 2, 2014, was released to the public. The trial version of OS X Yosemite came out on July 24, 2014. Time Machine requires an additional hard disk or AirPort Time Capsule (sold separate). Photo Booth requires a FireWire DV camcorder, USB video class (UVC), or FaceTime or iSight camera. Fixed focus, exposure, white balance, and white balance are required for DV camcorders. Video calls require a built in FaceTime camera, an iSight (built-in or external), a USB class (UVC), or a FireWire DV camera; and a 128Kbps upstream or downstream Internet connection. A FaceTime HD camera with a 1-Mbps downstream and upstream Internet connection is required to make HD video calls. HD video calls can only be received on an Intel-based Mac.