219 Green PC
FIGURE 122. Graphics tablet (Photo courtesy of Wacom Technology)
1. a series of boxes filled with a range of black tints from pure white to 100% black. A grayscale is used to test a printer, monitor, scanner, or printing press.
2. (scanner terminology) the range of grays in an image as measured by the scanner.
3. a description of any image that contains shades of gray as well as black and white.
Greek the alphabet used in ancient and modern Greece, Α ΒΓ Δ... W and a b’g d ... ω. Greek letters are often used as mathematical symbols. For the complete Greek alphabet, see page 6. Contrast CYRILLIC; LATIN.
greeking the use of random letters or marks to show the overall appearance of a printed page without showing the actual text. With computers, greeking is used when the page is displayed too small for the text to be readable on the screen.
FIGURE 123. Greeking
Green Book the Philips/Sony standard for multimedia interactive compact discs (not including personal computer software).
Green PC a personal computer that draws little electrical power when idle, even though still turned on. AGreen PC typically stops spinning its hard
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disk and shuts down power to the monitor if several minutes elapse with no keyboard activity. See also ENERGY STAR.
Gregorian calendar the calendar system presently in use, introduced by Pope Gregory in 1582 and adopted in England in 1752 and in Russia in 1918. It is exactly like the Julian calendar except that years divisible by 100 are not leap years unless they are also divisible by 400. The Gregorian calendar thus follows the earth’s revolution around the sun more accurately than the Julian calendar did. See LEAP YEAR.
grep the UNIX command that reads a text file and outputs all the lines that contain a particular series of characters. For example, the command
grep abc myfile
reads the file myfile and outputs every line that contains “abc.”
Instead of specifying the exact characters to be searched for, you can give a regular expression that defines them. For example,
grep [bB]ill myfile
outputs all the lines that contain either “bill” or “Bill.” See REGULAR EXPRESSION.
The origin of the word grep is disputed, but it may be an abbreviated editing command, g/re/p, where re stands for “regular expression,” gmeans “global search,” and pmeans “print” (i.e., display all lines that match the search criteria). Grep programs have been written for other operating systems, such as Windows. Compare FIND.
grid a feature of various draw programs and paint programs that allows lines to be drawn only in certain positions, as if they were drawn on the lines of graph paper. The grid makes it much easier to draw parallel and perpendicular lines, lay out diagrams, and avoid irregular breaks. However, when the grid is turned on, there are positions in which you cannot draw. See also DRAW PROGRAM; PAINT PROGRAM.
grid computing the process of solving computationally complicated prob-lems by distributing parts of the problem to unused capacity on a widely dispersed set of machines that are connected to the Internet.
For examples, see SETI@HOME; TERAGRID; and www.grid.org. For con-trast, see CLUSTER COMPUTING.
grid system a way of standardizing the layout of many related pages, such as the pages of a multipage document. The designer first draws a grid that will define the possible positions of columns, horizontal divisions, and pictures. Not all the possibilities of the grid are used on any single page, but the grid ensures that column positions do not vary haphazardly, and thereby makes the pages look related.
griefer (slang) a person who plays a multiplayer game or participates in other online group activities for the purpose of making other people mis-erable. Griefers do not play to win; they do not defeat their opponents
fairly. They play to lose, and they dish out insults, misinformation, and harassment in the process.
Grokster a file sharing service found liable for inducing its users to violate copyright law, in the case Metro-Goldwyn-Mayer Studios et al. v. Grokster (545 U.S. 913 (2005)), decided by the Supreme Court in 2005. See also NAPSTER.
gross megapixels the total number of megapixels on an image sensor, whether or not all of them are actually used in taking pictures. Contrast EFFECTIVE MEGAPIXELS.
grounding the establishment of a uniform reference voltage level across several pieces of electrical equipment that are connected together.
In any electrical device, “ground level” is the voltage level to which all other voltages are compared. In most computers, the ground level is connected to the ground pin (the third, rounded pin) of the power plug, and the power line then connects it to the earth itself, thereby assuring that the ground level for all machines is the same. This helps prevent cables from picking up noise or emitting radio-frequency interference. It also reduces the danger of damage from lightning. See ELECTRONIC CIR-CUIT DIAGRAM SYMBOLS; POWER LINE PROTECTION; RFI PROTECTION.
groupware software that makes it easy for a group of people to work on the same data through a network, by facilitating file sharing and other forms of communication. Lotus Notes is an example of widely used groupware.
GTG chat-room abbreviation for “[I’ve] got to go.”
gTLD (generic Top Level Domain) an identifier such as .com or .edu at the end of a U.S. web address; see www.iana.org/domains/root/db/# for the complete list of possibilities. See also CCTLD; TLD.
GUI see GRAPHICAL USER INTERFACE.
GUID (Globally Unique Identifier) a 128-bit number used by Microsoft WINDOWS to identify a user, software component, or other entity.
GUIDs are most often written as groups of hexadecimal digits in braces, such as:
Windows includes an algorithm to generate GUIDs based on an encrypted version of the user’s MAC ADDRESS, which in turn is guaranteed to be unique. (See MAC ADDRESS.) Thus, anyone running Windows who has an Ethernet adapter can create GUIDs that are known to be unique in the entire world. Computers without an Ethernet adapter can generate GUIDs that are likely to be unique but not guaranteed to be.
guideline a nonprinting line that aids in aligning text and other objects in a draw program or page layout program. Some programs allow you to turn
on a snap-to-guidelines feature that causes the guidelines and objects to have a magnetic attraction for each other. See also SNAP-TO-GRID.
guiltware persistent NAGWARE; software that repeatedly asks for a mone-tary contribution and tries to make you feel guilty if you don’t pay. Contrast CAREWARE; FREEWARE.
gunk (slang) any undesirable thing that degrades the performance of a computer, such as physical dust, obsolete software, or spyware. Gunk includes well-intentioned utilities that waste CPU time constantly mon-itoring the status of a modem, network card, or disk drive, as well as VIRUSES, ADWARE, and other MALWARE.
gutterthe blank space between columns of type or between pages of a book.
h4x LEETSPEAK for “hacks.” See HACK, especially definition 4.
1. to modify, especially in an improvised way: “This version of the pro-gram has been hacked to run under UNIX instead of Windows.”
2. to program a computer, either tediously or enthusiastically: “We spent the whole night hacking.”
3. to break into a computer system or otherwise do mischief: “We’ve been hacked.” See also ETHICAL HACKING.
4. a clever programming technique: “This hack enables a console-mode program to change the title bar of its window.”
When someone in an online game is accused of “hacks,” it means that he or she is suspected of using software bugs or a third-party program to achieve results that the game designers did not intend.
hack attack (slang) a sudden inspiration or compulsion to work on a com-puter program. Despite what it sounds like, a “hack attack” has nothing to do with computer security violations.
1. an exceptionally skilled computer programmer.
2. a person who programs computers for recreation or as a hobby.
3. a person who “breaks into” computers without authorization, either for malicious reasons or just to prove it can be done; a CRACKER. See 2600; COMPUTER SECURITY
hacker ethic the value system of computer enthusiasts who believe in help-ing each other advance technology by sharing knowledge without imme-diate concern for making money. See HACKER (definition 2). The hacker ethic has led to valuable cooperative projects such as GNU, LINUX, TEX, USENET, and the INTERNET.
Usage note: The term hacker ethic is sometimes misappropriated by malicious individuals who believe they are somehow exempt from ordi-nary rules of ethics (see HACKER, definition 3). In its proper sense, the hacker ethic is an extension of ordinary ethics, not an exemption or loop-hole.
Hacker Safe see SCANALTERT
hackish (slang) pertaining to the culture of HACKERs (definitions 1 and 2 and sometimes 3). For instance, using binary numbers on a birthday cake is a hackish thing to do.
hafnium chemical element (atomic number 72) used as an insulator in inte-grated circuit transistors.
nguon tai.lieu . vn