Windows

bootstrap loader

(from "{bootstrap" or "to pull oneself up
by one's bootstraps") A short program that was read in from
cards or paper tape, or toggled in from the front
panel switches, which read in a more complex program to
which it gave control.

On early computers the bootstrap loader was always very short
(great efforts were expended on making it short in order to
minimise the labour and chance of error involved in toggling
it in), but was just smart enough to read in a slightly more
complex program (usually from a card or paper tape
reader), to which it handed control; this program in turn
was smart enough to read the application or operating
system from a magnetic tape drive or disk drive. Thus,
in successive steps, the computer "pulled itself up by its
bootstraps" to a useful operating state. Nowadays the
bootstrap is usually found in ROM or EPROM, and reads the
first stage in from a fixed location on the disk, called the
"{boot block". When this program gains control, it is
powerful enough to load the actual OS and hand control over
to it.

See boot.