Two major hardware revisions of the Xbox 360 have succeeded the original models; the Xbox 360 S (also referred to as the "Slim") replaced the original "Elite" and "Arcade" models in 2010. The S model carries a smaller, streamlined appearance with an angular case, and utilizes a redesigned motherboard designed to alleviate the hardware and overheating issues experienced by prior models. It also includes a proprietary port for use with the Kinect sensor. The Xbox 360 E, a further streamlined variation of the 360 S with a two-tone rectangular case inspired by Xbox One, was released in 2013. In addition to its revised aesthetics, Xbox 360 E also has one fewer USB port and no longer supports S/PDIF.
How many USB ports did the S model have?