Online Computer Terms Dictionary - B

bootstrap

<operating system, compiler> To load and initialise the operating system on a computer. Normally abbreviated to "boot". From the curious expression "to pull oneself up by one's bootstraps", one of the legendary feats of Baron von Munchhausen. The bootstrap loader is the program that runs on the computer before any (normal) program can run. Derived terms include reboot, cold boot, warm boot, soft boot and hard boot.

The term also applies to the use of a compiler to compile itself. The usual process is to write an interpreter for a language, L, in some other existing language. The compiler is then written in L and the interpreter is used to run it. This produces an executable for compiling programs in L from the source of the compiler in L. This technique is often used to verify the correctness of a compiler. It was first used in the LISP community.

See also My Favourite Toy Language.

[Jargon File]

(2005-04-12)

bootstrap loader

<operating system> A short program loaded from non-volatile storage and used to bootstrap a computer.

On early computers great efforts were expended on making the bootstrap loader short, in order to make it easy to toggle in via the front panel switches. It was just clever enough to read in a slightly more complex program (usually from punched cards or paper tape), to which it handed control. This program in turn 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 loader 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. A diskless workstation can use bootp to load its OS from the network.

(2005-04-12)