The off-line version of Ghost, which runs from bootable media in place of the installed operating system, originally faced a number of driver support difficulties due to limitations of the increasingly obsolete 16-bit DOS environment. Driver selection and configuration within DOS was non-trivial from the beginning, and the limited space available on floppy disks made disk cloning of several different disk controllers a difficult task, where different SCSI, USB, and CD-ROM drives were involved. Mouse support was possible but often left out due to the limited space for drivers on a floppy disk. Some devices such as USB often did not work using newer features such as USB 2.0, instead only operating at 1.0 speeds and taking hours to do what should have taken only a few minutes. As widespread support for DOS went into decline, it became increasingly difficult to get hardware drivers for DOS for the newer hardware.