Barrons Publishing Dictionary of Computer and Internet Terms 10th

FIGURE 249. Start button and start menu (Windows)

statement a single instruction in a computer programming language. One statement may consist of several operations, such as X = Y+Z/W (a division, an addition, and an assignment). See PROGRAMMING LANGUAGE.

static

1.in C and related programming languages, a keyword indicating that a variable continues to exist even when the function that defines it is not in use. That is, a static variable remembers its value from one invocation of the function to the next.

2.in C++ and related programming languages, a keyword indicating that a variable exists, or a method can be called, without creating an object of the class to which it is attached, and if several such objects are created, they will all share one copy of the static item.

3.(describing electricity) standing still; accumulating as a charge rather than flowing in a circuit. Static electricity accumulating on the human body can damage integrated circuits when a person suddenly touches them. To prevent this, be sure to touch the frame of the computer before touching anything inside it, and use anti-static spray on carpets.

4.(describing audio or video) popping or frying sounds or speckled patterns like those caused by discharges of static electricity interfering with radio or television reception. In the digital world, this kind of static usually results from an insufficient data transmission rate, or corrupted data, rather than from static electricity.

static IP address an IP address that is assigned permanently to a computer. A static IP address is needed for any kind of server that people access through the Internet. Contrast DYNAMIC IP ADDRESS.

static RAM see SRAM.

stationery

1.paper, envelopes, and so forth on which information is to be printed.

2.a template for e-mail messages including colors and graphics to give it a distinctive appearance, implemented by using HTML.

statistics program a software package for performing statistical calculations.

A statistics program works with lists of numbers instead of single values. It should have built-in commands for calculating the average and standard deviation of the elements of a list, for testing hypotheses about the relationships between variables through methods such as multiple regression, for performing transformations (such as taking the logarithm of each of the elements in a list), and for drawing graphs of the data. Examples of statistics programs include SAS (Statistical Analysis System) and SPSS (Statistical Program for the Social Sciences).

status line a line of information on the computer screen that indicates the current settings of the software and the current cursor position. The contents of a status line will vary depending on the software used; some programs give different information during the execution of different commands. It is a good idea to get into the habit of noticing what is in the status line. If you do not understand what you see there, take a moment to review the manual.

FIGURE 250. Status line

steganography the concealment of a small message inside a larger file that appears to consist entirely of something else. For example, an encrypted message might be hidden among some slight variations of color at selected points in a picture. Crucially, a person viewing the picture would not know that a message was concealed in it. Messages can also be hidden in inaudible low-level noise superimposed on digitized music.

Steganography goes hand-in-hand with encryption but is not the same thing. Encryption makes a message unreadable by unauthorized persons; steganography hides the very existence of the message. See also CRYPTOGRAPHY; ENCRYPTION.

stochastic random; constantly varying; unpredictable; scattered.

storage area network a computer network that shares disk space using

DISK SHARING rather than FILE SHARING. Contrast NETWORK ATTACHED STORAGE.

store to place a data item into a memory device.

stored program computer a computer that can store its own instructions as well as data. All modern computers are of this type. The concept was

originated by Charles Babbage in the 19th century and was developed by John Von Neumann. The ability of a computer to store instructions allows it to perform many tasks without human intervention. The instructions are usually written in a programming language. See COMPUTER.

Storm worm a WORM virus introduced in 2007 that linked thousands of computers into a ZOMBIE network.

stream

1.audio or video content made available by streaming (definition 1).

2.(noun) in C++, Lisp, and other computer languages, a file or device that can be read or written one character at a time. For example, the screen and keyboard can be treated as streams.

3.(verb) to move tape past a read-write head continuously, rather than making short movements with pauses in between.

streaming

1.delivering audio or video signals in real time, without waiting for a whole file to download before playing it. See REALAUDIO.

2.moving a tape continuously. See STREAM (definition 3).

stretch to increase or reduce either the vertical or horizontal dimension of an object, thereby changing its overall shape. To use the mouse to stretch a selected object interactively, drag out one of the handles at the midpoints of the BOUNDING BOX. Contrast SCALE, which maintains the height-to-width ratio of the object.

FIGURE 251. Stretch

string (character string) a sequence of characters stored in a computer and treated as a single data item. See STRING OPERATIONS.

string operations operations that are performed on character string data. Here are some examples from Java, where A represents the string

”GEORGE” and B represents ”WASHINGTON”:

1.Compare two strings to see if they are the same. For example, A.equals(B) (in other programming languages, A==B or A=B) will be false.

2.Determine if one string comes before the other in alphabetical order. For example,

A.compareTo(B)<=0

will be true (because GEORGE comes before WASHINGTON). In other programming languages this is expressed as A<B.

striping the practice of spreading consecutive data blocks across different disk drives (e.g., block 1 on disk 1, block 2 on disk 2, block 3 on disk 1 again, and so on). See RAID.

struct in C and C#, a data structure consisting of several simpler items grouped together.

A struct is not an OBJECT; that is, a struct cannot have METHODs. Java does not have structs; it uses only classes (object types). C# has both.

See also CLASS; OBJECT-ORIENTED PROGRAMMING.

structured programming a programming technique that emphasizes clear logic, modularity, and avoidance of GO TO statements (which are intrinsically error-prone).

One of the most important barriers to the development of better computer software is the limited ability of human beings to understand the programs that they write. Structured programming is a style of programming designed to make programs more comprehensible and programming errors less frequent. Because it is more a popular movement than a precise theory, structured programming can be defined in several ways, but it usually includes the following;

1.Block structure. The statements in the program must be organized into functional groups. For example, of the following two Pascal program fragments, the first is structured, while the second is not:

WRITELN(z,q);

Note that it is much easier to tell what the first example does.

2.Avoidance of jumps (“GO-TO-less programming”). It can be proved mathematically that, if a language has structures equivalent to the (block-structured) IF-THEN and WHILE statements in Pascal, it does not need a GO TO statement. Moreover, GO TO statements are often involved in programming errors; the programmer becomes confused as to the exact conditions under which a particular group of statements will execute.

Advocates of structured programming allow GO TO statements only under very restricted circumstances (e.g., to deal with error conditions that completely break out of the logic of a program) or not at all.

3.Modularity. lf a sequence of statements continues uninterrupted for more than about 50 lines, human beings have a hard time understanding it because there is too much information for them to keep track of. As an alternative, programs should be broken up into subroutines, even if some of the subroutines are called only once. Then the main program will read like an outline, and the programmer will never need to understand more than about one page of code at a time. (The programmer must know what the subroutines do, but not how they do it.) This principle is sometimes called information hiding—irrelevant information should be kept out of the programmer’s way. Structured programming was first advocated by E. W. Dijkstra in the early 1970s.

stub

1.a temporary substitute for a part of a computer program that has not yet been written. For instance, if a procedure to read numbers from a file has not yet been written, the programmer might put in a stub that simply gives the same number every time, so that the rest of the program can proceed.

2.a declaration that tells how to call a method or function that is defined elsewhere.

StudlyCaps (slang) INTERCAPS. See also PASCAL NOTATION.

StuffIt a data compression program for Macintosh and Windows written by Raymond Lau. Like ZIP and WinZip, StuffIt allows several files to be combined into one. StuffIt can also encode and decode BinHex files. A free StuffIt expander program can be downloaded from www.stuffit.com. See DATA COMPRESSION; ZIP FILE.

style (of type) a particular kind of type, either plain, boldface, or italic, belonging to a specified font. See FONT; TYPEFACE.

FIGURE 252. Styles of Helvetica type

style sheet a file (in WordPerfect, LATEX, HTML, and other publishing programs) that defines the overall layout and type specifications of a document or web page. See

GRID SYSTEM.

stylus

1. the pen-like part of a graphics tablet (See Figure 122 at GRAPHICS TABLET, page 219). They may contain sophisticated electronics to improve accuracy and measure the pressure placed on the tablet by the artist.

2. a sharp, pen-like device used for pressing on the touchscreen of a handheld computer or PDA. The stylus contains no electronic parts; any object that has a non-marking point but is not too sharp will do the job.

subdirectory a disk directory that is stored in another directory. See

DIRECTORY.

subnet mask a bit pattern, usually written as four numbers, that indicates which parts of an IP address belong to the same network.

The most common subnet mask is 255.255.255.0, which indicates that the first three numbers of the IP address are the same throughout the network. An alternative on larger networks is 255.255.0.0, which indicates that only the first two numbers are the same. Here 255 means “the number in this position is the same throughout the network” and 0 means “this number varies from computer to computer.”

More technically, subnet masks are 32-bit binary numbers which are logically ANDed with an IP address to extract the part that identifies the network.

subroutine a set of instructions, given a particular name or address, that will be executed when the main program calls for it. In most newer programming languages, subroutines are called FUNCTIONs, PROCEDUREs, or

METHODs. See STRUCTURED PROGRAMMING; TOP-DOWN PROGRAMMING.

subscript a number or other indicator used to identify a particular element in an array. In mathematics, subscripts are written below the main line, as in x1 or ak. In most computer languages, however, subscripts are enclosed by square brackets, as in X[1] or A[K]. See ARRAY.

subscripted variable array variable. See ARRAY.

subwoofer a speaker that reproduces only very low-frequency sounds, used to supplement the other speakers in an audio system.

suit (slang) a manager or salesman; a (male) worker in the computer industry who is neither an engineer nor a programmer and is therefore not allowed to dress casually.

suitcase (Macintosh) a special kind of folder that contains system resources (fonts, sounds, desk accessories). For example, you can manage your fonts by keeping them grouped logically in suitcases. Some prefer to store their fonts in typeface families—others group fonts used for specific projects in separate suitcases.

suite a set of application software from a single vendor that attempts to span the basic uses of a computer. A suite usually has a word processor, a database, and a spreadsheet. The advantage of using a suite is compatibility; you are assured that all of the programs can accept data from any of the others and incorporate them in their own files. On the downside, the individual programs of a software suite sometimes lack desirable features. If additional software is purchased, it may be difficult to get the programs to work together.

Sun Microsystems, Inc. (Mountain View, California) the company that developed SPARC microprocessors, SUN WORKSTATIONS, the SOLARIS operating system, and the JAVA programming language. Web address: www.sun.com.

Sun workstations high-performance desktop computers manufactured by Sun Microsystems of Mountain View, California. Most are marketed as single-user systems, although each can support more than one user. All run Solaris (SunOS), a proprietary version of UNIX based on System V and incorporating some BSD features.

Sun workstations dominated academic computer networking in the 1990s, before PCs were fully network-capable. During their heyday, most Sun workstations used Sun’s proprietary RISC microprocessor called SPARC. Today, Sun workstations use Intel and AMD microprocessors, and Sun’s product line has shifted toward servers. See BSD; SPARC; UNIX; WORKSTATION.

superclass a class from which another class in an object-oriented programming language is descended. For example, if your applet program myapplet extends the class Applet, then Applet is the superclass for myapplet.

See EXTENDS.

supercomputer a computer designed to run markedly faster than ordinary mainframe computers, generally by using parallel processing. Examples are the Cray vector processors and the Intel iPSC parallel processor.

superior character a superscript; small letters and numbers set above the baseline like this. Used mainly in mathematical typesetting. See

SCRIPT. Contrast INFERIOR CHARACTER; SUBSCRIPT.

superscalar processor a computer that is in between conventional SCALAR PROCESSOR and VECTOR PROCESSOR architectures; it accepts instructions like those of a scalar processor but has some ability to double them up and do more than one thing at once at runtime. The PENTIUM is an example of a superscalar processor.

superscript a small character written above the baseline, like this. In mathematics, a superscript indicates an exponent, which denotes repeated multiplication. For example, 43 = 4 × 4 × 4.

supertwist a newer type of liquid crystal display (LCD) that produces higher contrast than earlier types. An LCD works by twisting light waves to change their polarization. Supertwist displays produce more of a change in polarization than their predecessors.

support ticket See TICKET.

surface computing working on a computer screen that is not a traditional monitor; for example, a tabletop that has a built-in touchscreen computer display.

surface mapping the act of applying a surface (complete with color, pattern, shading, and texture) to a 3D wireframe model. See RENDER.

surfing (slang) the practice of browsing the WORLD WIDE WEB or other information services, much like a surfer riding one wave and then another.

surge protector device that absorbs brief bursts of excessive voltage coming in from the AC power line. These surges are created by lightning or by electric motors switching off.

Surge protectors do little good unless the power line is properly grounded. Always plug the computer into a properly grounded outlet. If possible, do not plug a laser printer into the same outlet strip or extension cord as the computer, because laser printers draw heavy current intermittently.

Many surge protectors also incorporate RFI protectors to help reduce radio and TV interference emitted by the computer into the power line. (See RFI PROTECTION.) A surge protector cannot do anything about momentary power failures; for that, you need an uninterruptible power supply.

See also POWER LINE PROTECTION; UNINTERRUPTIBLE POWER SUPPLY.

surround sound a system of sound reproduction where there are speakers in several directions from the listener (Fig. 253). This contrasts with stereophonic sound, with just left and right speakers, and monophonic sound, with just one speaker (or multiple speakers playing the same signal).

Several systems have been developed for encoding and decoding surround sound in a two-channel stereo signal, and many computer SOUND CARDs now have surround-sound output. See 5.1; 6.1; 7.1.

FIGURE 253. Surround sound (5.1 speaker arrangement)

suspend to stop the CPU and input-output devices of a computer while leaving the contents of memory in place, so that it can resume where it left off without rebooting. Unlike a hibernating computer, a suspended computer continues to consume a small amount of battery power.

Contrast HIBERNATE.

SVGA (Super VGA) a video resolution of 800 × 600 pixels. Contrast XGA.

swap file a file used for swap space. In Windows, the swap file is hidden and does not normally appear in directory listings (see HIDDEN FILE). It can be either permanent, and fixed in size, or temporary, and varying in size. Permanent swap files give faster program execution.

Besides the swap file used by the operating system, there are also swap files used by particular applications, such as Adobe PhotoShop.

See

swap space disk space that an operating system or program uses as a substitute for additional memory. See VIRTUAL MEMORY; SWAP FILE.

swash a capital letter with a decorative flourish. Swashes are best used sparingly.

FIGURE 254. Swash capital letters

.swf (Shockwave file) filename extension used by Macromedia Shockwave. See SHOCKWAVE.

swipe see TRANSITION EFFECT.

switch

1.in electronics, a device for interrupting or rerouting the flow of electric current.

2.in telecommunications and networking, a device for establishing connections between one location and another, doing the work of a telephone operator. For instance, on a computer network, a switch is a device that temporarily creates high-speed paths between different segments as they are needed. It works like a hub but does not add congestion to cables on which the traffic is not actually needed. See BRIDGE.

Compare HUB; ROUTER.

3.in C and its derivatives, a statement for choosing different actions corresponding to different values of a variable. Each section must end with break unless you want execution to continue in the next section. Here is an example in Java:

switch (p)

{

case 1:

System.out.println(”First place\n”); break;

case 2:

System.out.println(”Second place\n”); break;

case 3:

System.out.println(”Third place\n”); break; default:

System.out.println(”Something else\n”);

}