hard boot

<operating system>

A boot which resets the entire system.

The phrase has connations of hostility toward, or frustration with, the computer being booted. For example, "I'll have to hard boot this losing Sun", or "I recommend booting it hard".

Hard boots are often performed with a power cycle.

Contrast soft boot. See also cold boot and reboot

[Jargon File]

Last updated: 1995-11-27



(By analogy with "hard-wired") Said of a data value or behaviour written directly into a program, possibly in multiple places, where it cannot be easily modified. There are several alternatives, depending on how often the value is likely to change. It may be replaced with a compile-time constant, such as a C "#define" macro, in which case a change will still require recompilation; or it may be read at run time from a profile, resource (see de-rezz), or environment variable that a user can easily modify; or it may be read as part of the program's input data.

To change something hard-coded requires recompilation (if using a compiled language of course) but, more seriously, it requires sufficient understanding of the implementation to be sure that the change will not introduce inconsistency and cause the program to fail.

For example, "The line terminator is hard-coded as newline; who in their right mind would use anything else?"

See magic number.

[Jargon File]

Last updated: 1999-10-18



A paper printout of data displayed on a screen.

Contrast softcopy.

Last updated: 1995-08-31

hard crash


When a program stops running completely and unexpectedly, often due to external events, e.g. the CPU overheating or an unrecoverable memory error.

See also disk crash.

Last updated: 2009-07-01

hard disk


(In contrast to floppy disk) A magnetic disk data storage device where the disks are rigid and fixed to a central axle. They are usually packaged with associated read/write heads and electronics. Most hard disks are permanently connected to the drive (fixed disks) though there are also removable hard disks.

See magnetic disk.

Last updated: 2007-06-14

hard disk drive


(HDD) A disk drive used to read and write hard disks.

Last updated: 1995-03-14

hard drive

hard disk drive

hard link

<file system>

One of several directory entries which refer to the same Unix file. A hard link is created with the "ln" (link) command:

 ln <old name> <new name>

where <old name> and <new name> are pathnames within the same file system. Hard links to the same file are indistinguishable from each other except that they have different pathnames. They all refer to the same inode and the inode contains all the information about a file.

The standard ln command does not usually allow you to create a hard link to a directory, chiefly because the standard rm and rmdir commands do not allow you to delete such a link. Some systems provide link and unlink commands which give direct access to the system calls of the same name, for which no such restrictions apply.

Normally all hard links to a file must be in the same file system because a directory entry just relates a pathname to an inode within the same file system. The only exception is a mount point.

The restrictions on hard links to directories and between file systems are very common but are not mandated by POSIX. Symbolic links are often used instead of hard links because they do not suffer from these restrictions.

The space associated with a file is not freed until all the hard links to the file are deleted. This explains why the system call to delete a file is called "unlink".

Microsoft Windows NTFS supports hard links via the fsutil command.

Unix manual page: ln(1).


Last updated: 2004-02-24

hard linking

hard link

hard sector


An archaic floppy disk format employing multiple synchronisation holes in the media to define the sectors.

Last updated: 1995-01-24



The physical, touchable, material parts of a computer or other system. The term is used to distinguish these fixed parts of a system from the more changeable software or data components which it executes, stores, or carries.

Typical computer hardware consists of electronic devices (CPU, memory, display) with some electromechanical parts (keyboard, printer, disk drives, tape drives, loudspeakers) for input, output and storage. Completely non-electronic (mechanical, electromechanical, hydraulic, biological) computers have also been conceived of and built.

See also firmware, wetware.

Last updated: 1997-01-23

Hardware Abstraction Layer

<operating system>

(HAL) The layer of Microsoft Windows NT where they have isolated their assembly language code.

Last updated: 1995-04-17

hardware circular buffer

<programming, hardware>

digital signal processors which support hardware circular buffers automatically generate and increment pointers for memory accesses which wrap to the beginning of the buffer when its end is reached, thus saving the time and instructions otherwise needed to ensure that the address pointer stays within the boundary of the buffer, and speeding the execution of repetitive DSP algorithms.

Digital Signal Processor For Digital Audio Applications.

Last updated: 2000-06-17

Hardware Description Language


(HDL) A kind of language used for the conceptual design of integrated circuits. Examples are VHDL and Verilog.

Last updated: 1995-04-18

hardware handshaking


A technique for regulating the flow of data across an interface by means of signals carried on separate wires.

A common example is the RTS (Request to Send) and CTS (Clear to Send) signals on an EIA-232 serial line.

The alternative, software handshaking, uses two special characters inserted into the data stream to carry the same information.

Last updated: 1995-01-23

hardware register

<hardware, system administration>

(Or "hardware log") A list of all hardware, both internal and external, that is attached to a particular computer.

Last updated: 2006-09-07


/hard-weir'*-lee/ In a way pertaining to hardware. "The system is hardwarily unreliable." The adjective "hardwary" is *not* traditionally used, though it has recently been reported from the U.K.

See softwarily.

[Jargon File]

Last updated: 1995-01-23



1. An aspect of an electronic circuit which is determined by the wiring of the hardware, as opposed to being programmable in software or controlled by a switch.

<software, jargon>

2. In software, a synonym for hard-coded.

3. By extension, anything that is not modifiable, especially in the sense of customisable to one's particular needs or tastes.

[Jargon File]

Last updated: 1999-10-18

Nearby terms:

haptic interfacehapticshaquehard boothard-codedhardcopyhard crash

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