A small program that calls the operating system into memory (RAM) after the power is turned on. The boot loader may reside in the boot sector of the hard drive (or SSD) or in a chip. In more secure systems, the boot loader may load a second-level boot program, which then loads the operating system. Sometimes, the boot loader and boot manager, which enables one of several operating systems to be selected, are combined in the same program. See
boot,
boot manager,
boot sector and
secure boot.