< operating system > The magnetic disk (usually a hard disk ) from which an operating system kernel is loaded (or "bootstrapped"). This second phase in system start-up is performed by a simple bootstrap loader program held in ROM , possibly configured by data stored in some form of writable non-volatile storage .
MS-DOS and Microsoft Windows can be configured (in the BIOS ) to try to boot off either floppy disk or hard disk , in either order. By default they first check for the presence of a floppy disk in the drive at start-up and try to use that as a boot disk if present. If no disk is in the drive they then try to boot off the hard disk.
Some operating systems , notably SunOS and Solaris , can be configured to boot from a network rather than from disk. Such a system can thus run as a diskless workstation .
(1997-06-09)