It is a type of energy storage device. DataPower's firmware runs on a flash storage device. DVR is a DVR software designed for installation on a network-attached storage device. It is typically a proprietary solution, not compatible between various data storage device vendors. Paper data storage refers to the use of paper as a data storage device. The firmware simply loads and runs the first sector of the storage device. External USB floppy drives function as a USB Mass Storage Device. They act as a view or translation of an existing file system or storage device. In physical terms, most computer files are stored on some type of data storage device. Certain modchips enable the use of a USB hard drive or other mass storage device. The virtualization device in turn performs I/O to the storage device. This layer is concerned with the physical operation of the storage device (e.g. disk). They may be applied to program files on a storage device, or in computer memory. Early laptops simply had no built-in high-speed interface for supporting an external storage device. Frequently, retail systems are configured with a single file system occupying the entire storage device.