bootstrap loader

operating system (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 frontpanel 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 operatingsystem 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.

(27 November 1995)