Barrons Publishing Dictionary of Computer and Internet Terms 10th

FIGURE 274. Transistor action

In computers, transistors act as switches. The current flowing through the base controls the current flowing through the collector, turning it on or off under external control. See also ELECTRONIC CIRCUIT DIAGRAM SYMBOLS; INTEGRATED CIRCUIT; LOGIC CIRCUITS.

transition effect (in video editing and presentation software) a method of changing the scene from one view to another. Transition effects can give visual interest to a presentation by introducing an element of motion to the graphics. In video editing, they can help establish a change in location, or indicate the passage of time. There are literally hundreds of transition effects, and the exact terminology varies from program to program. Basically, there are four major types of transition effects:

1. Dissolve. Gradually replaces the first image with the second, either superimposing the pictures in mid-transition (like a double exposure) or replacing the image pixel-by-pixel or in larger blocks.

2. Swipe. The first image is seemingly wiped off, revealing the second image underneath. Swipes can go from left to right, right to left, up, or down, and the speed and the sharpness of the swipe edge can usually be controlled.

3. Fade. The image either darkens to black or lightens to pure white. 4. Fly-in. An image element moves in suddenly from off-screen.

It is wise to use transition effects sparingly. Not every editing cut or slide change merits special attention; in fact, overuse of distracting transitions will annoy and possibly confuse the audience.

translator

1. a program that exchanges data between application programs. See also EXPORT; FILTER; IMPORT.

2. a program that attempts to translate one human language into another.

See NATURAL LANGUAGE PROCESSING.

transparent

1.lacking visible effect. For instance, if a print-spooling program is transparent, all other software works just as if the print-spooling program were not installed. This is a desirable feature.

2.able to be seen through. Some graphics and paint programs have special features or filters to help you render transparent objects. Of special interest is the ability to adjust the opacity of objects or bitmaps via a sliding scale; the object can be totally opaque to totally transparent with many intermediate gradations. The in-between state where the image is recognizable but can be seen through is called ghosting.

transparent GIF a bitmap file whose background color is clear. A transparent GIF will seem to have irregular borders and float above the background.

transposition a common typing error where the order of two keystrokes is reversed. For example, “the” may be typed as “hte.” A is useful for catching transpositions.

trap

1.to detect an abnormal situation and take action. See TRY.

2.the area of overlap allowed between different colors of ink in a color printing job on a printing press. A slight amount of trap will prevent unintentional gaps between the two areas of color. Trap is needed only in processes that are patches of opaque ink, such as silkscreen or newspaper printing presses, but not on computer printers. See TRAPPING (definition 2).

trapping

1.the act of detecting and responding to events that would ordinarily interrupt the operation of the computer. For instance, some programming languages provide “error trapping,” which means that when the program attempts to do something impossible (such as divide by zero or read a file that doesn’t exist), control will be transferred to an error-handling routine supplied by the programmer. If no error trapping were provided, the program would simply end with an error message that might puzzle the user. In BASIC, trapping is activated by statements such as ON ERROR. For a Java example, see TRY.

2.the technique of aiding the REGISTRATION of color plates in a printing job by creating slight areas of overlap where two colors meet. See TRAP (definition 2).

Some software is capable of creating the trap automatically (see DESKTOP PUBLISHING; PREPRESS). At other times, the designer will have to

overlap design elements intentionally to ensure full coverage, even with a slight misregistration.

Trapping is only necessary when preparing CAMERA-READY COPY for a printing press; there are no registration problems when printing directly from your computer to a color printer.

the list). The algorithm that results is not quite as good as a binary search, but it is much better than having to work through the whole list. Furthermore, as with linked lists, new nodes can be added at any time without requiring that existing nodes be moved.

FIGURE 276. Tree (for binary search)

trialware software that you are allowed to use free for a limited period of time, but you must purchase it if you wish to continue using it when the trial period is over. See www.trialware.org.

trigonometric functions the mathematical functions that relate an angle to the lengths of the sides of a right triangle (Figure 277), defined thus:

If is small, sin ≈ tan ≈ (measured in radians).

See also

cause an EXCEPTION (an error condition) for which the programmer wishes to specify an action. For example:

/* This is Java */ try

{

theURL = new URL(urlbase,n0);

/* more statements can go here */

}

catch (MalformedURLException e)

{

System.out.println(”Bad URL: ”+theURL); /* more statements can go here */

}

finally

{

System.out.println(”All done.”);

}

The code within the try block will attempt to locate the specified URL. If successful, the program will proceed with the additional statements in the try block; if the URL is not valid, then it will execute the catch block (which displays a message for the user). Then, whether or not the exception occurred, the finally block will execute.

The advantage of this approach is that it saves the programmer from having to write separate if-then statements for each possible error that can occur. Instead, any error that arises in the try block can be processed by the catch block later on. This makes programs easier to read because the code for handling exceptional situations is clearly separated from the code for normal situations.

Also, the finally block provides a way to guarantee that certain statements will execute before leaving the try–catch–finally structure, no matter how this is done; even a goto or return statement will not get around it.

TS-CAL (Terminal Services—Client Access License) a license allowing more than the minimum number of users to access a Windows server through REMOTE DESKTOP. Without TS-CALs, depending on the version of Windows, only one or two users can access the computer at a time.

TSO (Time Sharing Option) the part of OS/360 and related IBM operating systems that supports timesharing terminals. TSO commands correspond to the various statements in JCL; for example, the allocate command corresponds to the JCL DD statement. See JCL.

TTFN, TT4N online abbreviations for “ta ta (i.e., good-bye) for now.”

TTL

1. (Transistor-Transistor Logic) a type of digital INTEGRATED CIRCUIT that requires an accurately regulated 5-volt power supply. Although TTL

has largely been replaced by CMOS circuitry, the original TTL voltage levels are still widely used on input-output devices. Contrast CMOS.

2. (through the lens) description of a light meter or viewfinder that uses the main lens of a camera, the same lens with which pictures are taken.

Compare SLR.

TTL monochrome monitor the type of monitor used with the original IBM monochrome display adapter (MDA) in the early 1980s. See MONITOR.

TTYL online abbreviation for “talk to you later.”

tune to improve the performance of a system by adjusting numerical parameters such as the size of the swap file, the time delays allowed for certain operations, and the like.

tunnel a private, secure link between two distant places that connects two local-area networks. For example, a company with two main offices may establish a tunnel between them using dial-up modems, leased telephone lines, or a secure (encrypted) connection over the Internet.

turbo the higher-speed mode on a computer that offers a choice of clock speeds. (Originally from turbocharger, a device for increasing the power of an automobile engine.)

Turbo Pascal an extremely popular Pascal compiler written by Anders Hejlsberg and introduced by Borland International in 1984, contributing greatly to the popularity of Pascal on microcomputers. Later versions included extensions for object-oriented programming. See also C++;

DELPHI.

Turing machine an imaginary machine conceived by Alan Turing in the 1930s to help identify the kinds of problems that are potentially solvable by machines.

The machine is a kind of simple computer. It consists of a long string of paper tape and a machine through which the tape can be fed. The machine can do four things: it can move the tape one space, it can place a mark on a space, it can erase a mark, or it can halt. Turing’s thesis states that this simple machine can solve any problem that can be expressed as an algorithm (if it has an unlimited supply of paper tape). As you might imagine, in practice it would be difficult to give instructions to a Turing machine so that it could solve a particular problem. The Turing machine is important theoretically, however, because it provides an indication of what kinds of problems computers can solve and what kinds they can never solve. See CHURCH’S THESIS.

Turing test a test proposed by Alan Turing in 1950 to determine whether machines have achieved human-like intelligence. According to the Turing test, a machine is intelligent if, under certain specified conditions, it is indistinguishable from a human when you carry on a conversation with it by teletype. For a critique, see ARTIFICIAL INTELLIGENCE;

ELIZA. See also CHURCH’S THESIS.

turnkey system a computer system that is ready to perform a particular task with no further preparation (“just turn the key and it does it”). A turnkey system is sold as a complete package from a single vendor.

turtle a pointer that moves around the screen leaving a trail as it goes and that is used to draw pictures in LOGO and related computer languages. Originally, the turtle was a small robot that rolled around on a large piece of paper, drawing a line.

Turtle graphics is a form of vector graphics. The turtle cannot be told to go to a particular position; it can only be told to turn through a particular angle and go a particular distance. See VECTOR GRAPHICS. For an example of turtle graphics programming, see LOGO.

TÜV (Technischer Uberwachungs-Verein, “technical supervision union”) a German organization that certifies that electronic equipment meets applicable safety standards and complies with government regulations.

TV

1.television (broadcast video).

2.(.tv) top-level-domain country code for Tuvalu, an island in the South Pacific, often used by television stations elsewhere.

3.(for “time value,” on a digital camera) shutter-priority autoexposure.

See S. Contrast A; AV; P.

TWAIN a protocol for delivering graphical images from a scanning or imaging device to application software. The name is said to stand for “technology without an interesting name.”

TWAIN strives to reduce the number of device drivers needed by providing a standard communication format. For more information about TWAIN, see www.twain.org. See also PROTOCOL.

twiddle (slang) to make small changes in settings.

twip (from “twentieth of a point”) a unit of distance equal to 1/1440 inch or 1/20 point, used in Windows graphics and RTF. Compare POINT (definition 2).

twisted pair a pair of unshielded wires twisted together, providing a cheap and relatively noise-free way to transmit signals. The two wires carry equal and opposite signals. Any electrical noise that they pick up will be the same (rather than opposite) in the two wires, and the circuitry on the receiving end can be designed to ignore it. Category-3, -5, and -6 cables are twisted pairs. Contrast COAXIAL CABLE.

Twitter the most popular microblogging web site (www.twitter.com), where users make posts of 140 characters or less.

type

1.letters printed or displayed by a computer. See TYPEFACE.

2.a kind of data item, such as integers, floating-point numbers, character strings, and pointers. See DATA STRUCTURES and entries for particular programming languages.

3.one of the distinguishable items in a set. For instance, the list {a,a,b,c,c} contains five tokens but only three types. Contrast TOKEN (definition 2).

4.(in Windows and other operating systems) the command that causes the contents of a text file to be displayed. For example,

type letter.txt

causes the file LETTER.TXT to be displayed on the screen. The equivalent UNIX command is cat.

Type 1 font an outline font format developed by Adobe Systems. Type 1 fonts are sets of mathematical descriptions of the letterforms as BÉZIER splines. In practical terms this means that it is possible to SCALE or size the type to practically any point size. (See VECTOR GRAPHICS.) TRUETYPE fonts are a competing format to Type 1 fonts. See also OPENTYPE.

type-identical alike, but not the same, such as two instances of the same word in different places in a text, or two copies of the same data in different places in memory. Contrast TOKEN-IDENTICAL.

typeface a particular design of lettering, in a consistent weight and style. Most of the typefaces used on computer printers today fall into the following categories (see Figure 278):

1.Roman type, proportionally spaced, with serifs. This kind of type originated with the stone engravers of ancient Rome. “Proportionally spaced” means that different letters are different widths (e.g., M is wider than I); serifs are the marks at the ends of the strokes (e.g., the

horizontal marks at the top and bottom of I). Times Roman is a popular roman typeface; it was designed by Stanley Morison for the London Times.

Roman type is the most readable kind of type and is used for the text of most books. Blocks of roman type should never be underlined; use italics instead (or boldface in some situations). Underlining text on typewriters was originally a substitute for italics.

Roman type usually includes some characters that are not on a typewriter, such as the dash (—) and distinct opening and closing quotation marks (“ ”). Be sure to use these where appropriate. See

TYPESETTING MISTAKES.

2. Sans-serif type, proportionally spaced. A popular typeface of this kind is Helvetica. Sans-serif type is better for short captions, posters, or labels, but can be tiring to read for long periods.

3. Fixed-pitch, typewriter-like typefaces. Courier and similar fixedpitch typefaces are used when all characters must be the same width in order to line up properly, such as in computer program listings (for an example, see COBOL), financial tables, and documents that were laid out for a fixed-pitch printer.