Hacker Originally, the term referred to a computer enthusiast who enjoys modifying computer hardware or software with the intent of mastering the computer system. In more recent times the term has been used (and some say misused) to refer to a person who gains illicit access to a computer system with the intention of doing harm.
Half Duplex The trasnmission of data in only one direction.  Devices that are designed or set to use half duplex are not able to communicate in both directions.
Handshake Handshake is what two devices do when before trying to communicate with each other. For example, when you use a modem, the noises you hear coming from the modem is your modem handshaking with the other. In the case of modems, handshaking is how two connecting modems agree on which transmission speed to use.
Hard disk A sealed mass storage device containing rigid, magnetically coated disks.
Hardware The physical equipment that makes up your computer systems.
Hashing A method in which you assign a string of characters a shorter value for easier location within a database. For example, let's say you need to search through a database and find certain people. If you use hashing and assign a number to each individual, then it'll be much easier to find a specific name using their (shorter) number than searching by name.
Heartbeat A message sent regularly (typically every few seconds) by the master system in a cluster to every system in the cluster to ensure that they are functioning correctly. If one system fails to respond to the heartbeat message, it is considered dead and the work that it was doing is taken over by another system in the cluster,
Heat Sink A device that is either built onto or attached to a microprocessor chip to help keep the chip cool. Typically, a heat sink looks like a series of spikes or fins rising out of the top of the chip, which channel heat away from the chip. Occasionally, the device takes the form of a fan that spins while the computer is on and blows the hot air away from the chip.
Hidden attribute The attribute assigned to a critical file to make it harder to access and more difficult to delete.
Hierarchical Organisation of data into a logical tree structure.
Hop The Internet and World Wide Web exist over a giant network of interconnected computers. When you surf to a particular Web site, you actually get there through a series of intermediate connections. Each of these intermediate connections is called a "hop." The more hops between you and your destination Web site, the longer it takes to get there.
Hot Pluggable/ Swappable A device is "hot swappable" or "hot pluggable" if you can add it to, or remove it from, your computer while the computer is running, without restarting the computer. Devices that you attach to the universal serial bus (USB) on newer computers are often hot-swappable devices.
Hotkey A "hotkey" is any key (or collection of keys) that perform tasks. They can be used to perform many operations like opening/saving files, formatting text, etc. Hotkeys can also be referred to as keyboard shortcuts. For example:
- F1 is a hotkey used by most programs to open up the help file
- Pressing the CTRL and S keys at the same time is a hotkey to save a file
HPGL Hewlett-Packard is famous for making printers and plotters. To standardise the way computers spoke to those printers and plotters, HP devised the HPGL, or Hewlett Packard Graphics Language. HPGL has been successful enough that most graphics programs and printers, from any manufacturer, can understand it.
Hub A device used to join computers and other network equipment to other computers, including servers.


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This page was last updated on Sunday, 14 December 2008