High Quality Content by WIKIPEDIA articles! The USB mass storage device class or USB MSC or UMS is a set of computing communications protocols defined by the USB Implementers Forum that run on the Universal Serial Bus. The standard provides an interface to a variety of storage devices. Devices which support this standard are referred to as MSC (Mass Storage Class) devices. While MSC is the official abbreviation, UMS (Universal Mass Storage) has become common in on-line jargon. There is no native (supplied by Microsoft) support for USB in Windows versions prior to Windows 95 and Windows NT 4.0, or MS-DOS. Windows 95 OSR2.1, an update to the operating system, featured very limited support for USB. During that time, no generic USB mass storage driver was produced by Microsoft, even for Windows 98. This meant that a device-specific driver was needed for each type of USB storage device.