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Barrons Publishing Dictionary of Computer and Internet Terms 10th

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software patent

446

unclear or unreasonable licenses, users should make a good-faith effort to obey copyright law and to avoid depriving the publisher of income. See also ACTIVATE (definition 3); EULA; FREE SOFTWARE; SHRINKWRAP LICENSE.

software patent a patent (a legal grant of exclusive ownership for a limited time to the creator of a work of intellectual property) that protects a computer program. In 1981, the U.S. Supreme Court ruled that software can be patented (Diamond v. Diehr). However, the issue is still controversial. Open source advocates (see www.nosoftwarepatents.com) think software patents impede innovation, since others are not allowed to use the patented software without a license from the patent owner. Patents are not supposed to be applied to ideas, such as mathematical theorems, but it may be difficult to distinguish patentable software code from a nonpatentable mathematical idea.

Others argue that patent protection is essential for software development because the programmers need to earn income from their work.

In 2005, the European Parliament rejected a proposal for a common system of software patents in the European Union. The issue is still being debated as this book goes to press.

SOHO abbreviation for “small office, home office.” (Soho is also the name of districts in London and New York City.)

Solaris the version of UNIX sold by Sun Microsystems. See SUN WORK-

STATIONS.

solder metal which is melted to join other metals without melting them. Most solder consists mainly of tin. Until recently, the solder in electronic equipment was usually 60% tin and 40% lead, but in order to reduce the amount of poisonous lead in landfills, the electronics industry is switching to tin-antimony and other lead-free solders. See ROHS.

solver

1.a computer program that solves equations that may have variables on either side of the equal sign, such as x = 1 + 1/x. This contrasts with ordinary calculators, spreadsheets, and programming languages, which can evaluate only expressions that consist entirely of known values.

2.an add-on for Microsoft Excel that can solve some kinds of optimization problems. The user specifies a target cell that is to be maximized or minimized; some cells representing variables that can be changed; and some constraints, such as specifying that the values in certain cells must be less than or greater than specific values.

sort to arrange items in numerical or alphabetical order.

Many different algorithms can be used to sort a group of items. If the number of items is small, it is probably best to use an algorithm that can be represented by a short program. If the number of data items is large, then it is more important to use a faster algorithm, even if it is complicated. Some algorithms assume that the data items have been read into the memory of the computer. However, if there is a very large number of items, it will be necessary to use an algorithm that works when the data items are

GO TO

447

spaghetti code

stored on an auxiliary storage device. Since sorting is such a common operation, many operating systems include built-in sorting algorithms. For examples of specific sorting algorithms, see BUBBLE SORT; INSERTION SORT; MERGE SORT; QUICKSORT; RADIX SORT; SELECTION SORT; SHELL SORT.

Sound Blaster a line of popular sound cards for PCs marketed by Creative Labs, Inc., of Milpitas, California. Their web address is www.soundblaster.com.

sound card a circuit board that can be added to a computer to enable or improve its ability to record and reproduce sound. Most current motherboards now include the function of a sound card, but higher audio quality can be obtained by adding a separate sound card. Sound cards often include other features such as a MIDI musical instrument interface, a controller for a CD-ROM drive, and an audio amplifier that can drive speakers. See Figure 244.

FIGURE 244. Sound card connections

source

1.see SOURCE CODE.

2.a place from which information is copied; the opposite of TARGET.

3.one of the three parts of a field-effect transistor (see FIELD-EFFECT

TRANSISTOR).

4. an audio signal.

source code

1.a computer program written in a programming language, such as C or Java, as opposed to the machine-language OBJECT CODE into which the compiler translates it. See COMPILER.

2.the HTML code or other special code that underlies a web page or other presentation. To view a web page as source code means to view the HTML code itself rather than the display that results from it. See HTML.

source program a program written in a programming language (e.g., Pascal, C, or C++) and fed into a computer. The compiler translates the program into a machine-language object program.

SP1, SP2 abbreviations for Service Pack 1 and Service Pack 2, which denote update packages for various software products.

spaghetti code (slang) a disorganized computer program using many statements, as easy to read as a plate of spaghetti. Contrast STRUCTURED PROGRAMMING.

spam

448

spam unsolicited and unwelcome advertisements sent to people via e-mail or posted in newsgroups. “Spammers” have discovered that they can reach a large audience at low cost on the Internet by posting the same message to all available newsgroups or e-mailing it to all possible addresses.

Spamming is considered seriously unethical for two reasons. First, newsgroups and e-mail would be useless if they routinely contained unwanted material. Second, the cost of transporting e-mail and newsgroup postings is not paid by the sender; it is paid by the recipient’s site and other sites along the way. Thus, it is important not to impose expenses on people by sending them unwanted material.

In some places, spamming by e-mail is illegal, and there is a strong movement to prohibit it everywhere. More importantly, almost all Internet service providers (ISPs) flatly prohibit both e-mail and newsgroup spam. The few ISPs that allow spamming are ostracized by other sites, which refuse to accept any data from them. See CAN-SPAM;

COMPUTER ETHICS; COMPUTER LAW; NETIQUETTE; ZOMBIE.

Experts advise that you should never reply to spam, even to ask to be taken off the mailing list, because that will merely tell the spammer that he has hit a valid address.

It is not clear why spam was named after a processed-meat product made by Hormel, but a Monty Python comedy act may be involved. For Hormel’s response to the situation, see www.spam.com.

spam filter a piece of software that distinguishes SPAM from ordinary e- mail. Spam filters are used in most major e-mail systems and can also run on an individual’s computer.

The way spam is recognized is kept secret, but it involves analysis of vocabulary, recognition of key phrases, and identification of known spam sites. To try to get around spam filters, spammers misspell the names of products and often include large numbers of irrelevant words.

See BAYESIAN SPAM FILTER.

spammer a person who sends out SPAM. Spammers are viewed with great contempt by the entire Internet community.

SPARC (Scalable Processor Architecture) a microprocessor developed by Sun Microsystems and used in Sun Sparcstations as well as computers made by other manufacturers. It uses RlSC architecture to achieve very high speed. See RISC; SUN WORKSTATIONS; WORKSTATION.

S/PDIF (Sony/Philips Digital Interface) a format for hardware and software for transferring digital audio files, used on CD players and other audio devices.

speaker-dependent, speaker-independent see SPEECH RECOGNITION.

special characters characters that cannot be typed directly from the keyboard, but require entering a special code or selection through the KeyCaps applet (Macintosh) or the Character Map (Windows).

Windows software accesses these special characters in many different ways. If you prefer to keep your hands on the keyboard, you can type

ANSI; EXPERT SET; IBM PC; UNICODE.

449

spell checker, spelling checker

most special characters by holding down the Alt key and typing a fourdigit code on the numeric keypad. (See the table of standard Windows characters at ANSI.) Macintosh users can type special characters by holding down the Option or Ctrl buttons while typing (here the Option key acts like another Shift key). KeyCaps lets you see which typewriter key corresponds to the desired character.

See also

specular highlight a bright point of light on a reflective or shiny surface.

speech recognition the use of computers to recognize spoken words. This is a nontrivial task because the same spoken word does not produce entirely the same sound waves when pronounced by different people or even when pronounced by the same person on more than one occasion. The computer must digitize the sound, transform it to discard unneeded information, and finally try to match it with words stored in a dictionary.

Most speech recognition systems are speaker-dependent; they have to be trained to recognize a particular person’s speech and can then distinguish thousands of words (but only the words they were trained on). Speaker-independent speech recognition is less effective. The biggest demand for speech recognition arises in situations in which typing is difficult or impossible, such as equipment for the handicapped, highly portable equipment, and computers that are to be accessed by telephone.

It is easier to recognize DISCRETE SPEECH (speech with pauses between words) than CONTINUOUS SPEECH, but discrete speech is slow and awkward. Hesitation noises (“uh,” “um”), coughs, and sneezes are sometimes mistaken for words.

speech synthesis the generation of human-like speech by computer (by computing the pronunciation of each word, not by playing back recordings).

Originally handled by special hardware, speech synthesis is now usually done by means of software running on a personal computer with a sound card. The technology to generate understandable speech has existed since the 1960s, but the speech is not completely natural; the intonation and timing are not perfect, and the voice may be monotonous and robot-like.

Speech synthesis is important in making computers accessible to blind people and delivering computer data by telephone. A speech synthesizer is built into Windows.

spell checker, spelling checker a program that checks the spelling of every word in a document by looking up each word in its dictionary. Many word processors do this as the words are typed. If the word does not appear in the dictionary, the user is alerted to a possible misspelling, and possible corrections are often suggested. Sometimes the correction will be made automatically, but you need to double-check to make sure that the resulting word is correct.

A spell checker will not recognize unusual proper names or specialized terms, but it will often allow you to create your own personal dic-

spider

450

tionary of specialized words you often use. (Be sure not to put misspelled words into it!) Spell checkers are valuable aids to proofreading, but they cannot catch the substitution of one correctly spelled word for another (such as form for from or to for too). Thus they do not guarantee that a document is free of spelling errors.

spider a program that explores the World Wide Web; a CRAWLER.

SPIM a SPAM message sent by instant messaging.

spin button a dialog box element that allows the user to change numbers rapidly by clicking on the up and down arrows or by typing the desired number directly into the number box.

FIGURE 245. Spin button

spindle count in a disk or file sharing system, the total number of actual disk drives (each with a stack of magnetic disks revolving around a single spindle).

splash screen a screen display or small window that appears briefly while a program is starting up, displaying its name, trademark, and version information.

spline a curve that connects a set of points smoothly. Figure 246 shows some examples. For details of computation, see B-SPLINE; BÉZIER SPLINE;

CUBIC SPLINE.

FIGURE 246. Splines (3 types)

sploit (slang; plural sploitz) an EXPLOIT; a way of breaching the security of a system.

spoofing the act of impersonating a user or a machine. For example, IP spoofing is the act of attaching a computer to the Internet using an IP ADDRESS assigned to a different computer, thereby intercepting communications intended for the other machine. See PHISHING.

451

spreadsheet

spooling the process of storing computer output before sending it to the printer. See PRINT SPOOLER.

spot color the use of a specified color of ink in a printing job. Spot color can be used for emphasis or to add interest to documents. Contrast PROCESS COLOR. These terms apply to mass-production printing with a printing press, not to inkjet or laser printers attached directly to computers.

spray can a tool found in various paint programs that leaves a circular pattern of the selected color. To use it, you press and hold down the mouse button and drag the mouse. The center of the spray pattern will be solid, but the edges will feather out to the background color. If you need a dense, solid color, move the mouse slowly; if you want a wispy trace of color, move the mouse rapidly. You can change the size of the spray can’s coverage area—usually by changing the brush size.

A similar tool is the AIRBRUSH. Generally, a program will have either an airbrush or a spray can tool, but not both.

FIGURE 247. Spray can

spread-spectrum a technique of radio transmission in which the frequency changes many times per second in a predetermined but seemingly random sequence. The receiver knows the sequence and follows the frequency changes. Spread-spectrum transmission overcomes interference because two transmitters will never be on the same frequency for more than a moment. Spread-spectrum transmission also provides privacy because the signal is almost impossible to intercept without knowing the sequence of frequency changes. See WIRELESS COMMUNICATION.

spreadsheet a table of numbers arranged in rows and columns. Paper spreadsheets were used for business data long before computers were invented. The first computer spreadsheet was VisiCalc, used on the Apple II computer in the late 1970s. Recently the most popular spreadsheets has been Microsoft Excel. Here are some general features of these programs:

1.Data is arranged in rows (labeled with numbers) and columns (labeled with letters). Each location in the spreadsheet is called a cell. You can enter numbers or letters in a cell, as in this example, which records the sales of different types of products at a small store:

 

A

B

C

D

 

 

 

 

 

1

Item

Price

Quantity

 

 

 

 

 

 

2

cereal

3.99

10

 

 

 

 

 

 

3

milk

2.15

25

 

 

 

 

 

 

4

toothpaste

1.95

7

 

 

 

 

 

 

spreadsheet

452

2.The computer will do calculations automatically if you enter formulas. For example, to calculate the revenue from the sale of cereal, enter the formula =B2*C2 in cell D2. (The asterisk * represents multiplication; the initial equal sign indicates this is a formula and not a label.

 

A

B

C

D

 

 

 

 

 

1

Item

Price

Quantity

Revenue

2

cereal

3.99

10

39.90

 

 

 

 

 

3

milk

2.15

25

 

 

 

 

 

 

4

toothpaste

1.95

7

 

 

 

 

 

 

When a formula is entered, the spreadsheet will display the result of the formula, not the formula itself, in that cell. However, moving the cell pointer to a cell will let you see the formula for that cell at the top of the screen, and you can edit it if needed.

3.A formula in one cell can be copied to other cells. For example, the formula in cell D2 can be copied to cells D3 and D4, which will give the total revenue for the other products:

 

A

B

C

D

 

 

 

 

 

1

Item

Price

Quantity

Revenue

2

cereal

3.99

10

39.90

 

 

 

 

 

3

milk

2.15

25

53.75

 

 

 

 

 

4

toothpaste

1.95

7

13.65

 

 

 

 

 

The copy command automatically changes formulas when they are copied to new cells. In the preceding example, when you copy the formula =B2*C2 from cell D2 to cell D3, it will become the formula =B3*C3, and in cell D4 it will become =B4*C4. This is because B2 and C2 in the formula in the original cell (D2) were written in the form of a RELATIVE ADDRESS. See ABSOLUTE ADDRESS to learn how to prevent the cell addresses from being changed by the copy command.

4.A formula can contain built-in functions, such as a command to sum all cells in a range. Entering Excel formula =SUM(D2:D4) into cell D5 will automatically calculate the column total (cells D2, D3, and D4). Many such functions are included with spreadsheet programs.

5.Spreadsheets are especially valuable because the formulas will be automatically recalculated whenever one of the numbers is changed. For example, if later in the month you update your sales figures, the program will automatically recalculate the revenue for

453

spyware

each item, and the total revenue. This makes spreadsheets especially useful for “what-if” analysis. You can design a spreadsheet with many variables, and see how the result changes when one or more of those variables are changed.

6.Spreadsheets can automatically create graphs of your data. For example, Figure 248 shows a pie chart giving the fraction of the sales of each item. Graphs can also illustrate how a variable changes with time, or how two variables are related to each other.

7.MACROs can be used to combine a series of keystrokes into one command, and advanced macros are themselves computer programs that can interact with users and process data.

8.Modern spreadsheets have added many features to improve the appearance of the output. For example, some cells can be displayed in boldface type, or a cell can be emphasized with shading.

9.Originally, spreadsheets were two-dimensional, making them analogous to putting all of your work on one giant piece of paper. Later spreadsheets added three-dimensional capability, which is analogous to keeping your work on different pages in a notebook. Also, modern spreadsheets allow different worksheets to be automatically linked together. For example, you can put your monthly sales figures in 12 different worksheets, and then have those linked to a single spreadsheet with year-end summary data.

See also EXCEL; LOTUS 1-2-3; MACRO.

FIGURE 248. Spreadsheets can create graphs such as this pie chart

sprite a moving element in a graphical display. Most video games use sprites.

spyware software that monitors a computer user’s activity without his or her knowledge and reports it to a central location. The purpose of spyware ranges from purportedly benign (enforcing copyrights, displaying targeted advertisements) to very malicious (stealing passwords and credit card numbers).

The most common way to get spyware on your computer is to install it yourself. This happens when you are tricked into installing free software that supposedly does something else, such as improve your computer’s performance or enable access to a web site.

SQL

454

Most spyware runs under Microsoft Windows, which formerly allowed web sites to download and install software on your computer automatically (see ACTIVEX). Current versions of Windows ask for permission before installing software, but it is very important for the user to be alert and not give this permission inappropriately. Above all, do not click on web site buttons that offer to do anything to your computer, such as check it or “optimize” it.

Software tools for detecting and removing spyware can be found at www.safer-networking.org and www.lavasoftusa.com. See also ADWARE;

MALWARE; VIRUS.

SQL (Structured Query Language, formerly Sequel) a standard query language used by many programs that manipulate large databases. Here is an example of an SQL query:

SELECT NAME, SALARY FROM TABLE1

WHERE SALARY > 35000

This means “Give me the name and salary from each row in TABLE1 where the salary is more than 35,000.” See QUERY LANGUAGE; RELATIONAL DATABASE.

square brackets the characters [ ], also called simply brackets. Contrast

ANGLE BRACKETS; CURLY BRACKETS; PARENTHESES.

SRAM (Static Random-Access Memory, pronounced “S-ram”) a type of computer memory that does not require a periodic refresh signal. SRAM is more expensive than DRAM and is rarely used as the main memory of a computer system, but it is often used for caches, video memory, and microcontroller systems. See MEMORY; RAM. Contrast DRAM.

SRC HTML keyword that indicates the file that serves as the source of an image or multimedia data. For example, see HTML.

SSL (Secure Socket Layer) an encryption system developed by Netscape based on RSA ENCRYPTION. SSL protects the privacy of data exchanged by the web site and the individual user. It is used by web sites whose names begin with https instead of http.

stack

1. a data structure from which items are removed in the reverse order from which they were inserted; also called a pushdown stack or pushdown store.

For example, when a program calls a subroutine, information about how to return to the main program is usually placed on the stack. If the subroutine then calls another subroutine, information about how to return to the first subroutine is placed on the stack. Since this information is retrieved from the stack in the opposite order from which it was placed there, each subroutine returns control to the right place.

Stacks are very useful for dealing with one operation nested inside another. To push a data item is to place it on a stack; to pop the stack is to remove an item from it. Contrast QUEUE.

455

starvation

2. A set of DEVICE DRIVERs loaded in a specific order to implement a function such as TCP/IP.

stacking order the order in which objects are arranged in a drawing program. This order determines which objects overlay others. Commands to reorganize the stacking order (Send to Front, Send to Back, Forward One, Back One) are usually found under an Arrange menu. Compare Z- ORDER.

Standard Generalized Markup Language, SGML a standard set of codes for marking boldface, italics, and so on, in ASCII text files, which became the basis for HTML. See HTML; XML.

standard input, standard output the input and output streams that a computer program reads and writes when not told to use a file; in CONSOLE MODE, the keyboard and screen.

star the character * (asterisk).

star dot star the WILD CARD character sequence *.*, which matches all Windows filenames.

star key the key on a telephone keypad marked with the symbol *. It is often used to give commands to software at the telephone company (e.g., to disable CALL WAITING).

Start button a button, labeled “Start. . . ”, that is normally on the screen whenever Windows is running. By clicking on the Start button, you can access application programs and other functions of the computer through the START MENU.

If the Start button is not visible, it’s probably because the TASKBAR at the bottom of the screen has been reduced to minimum width. Just move the mouse pointer to where it ought to be, and it will appear. By dragging the taskbar with the mouse cursor, you can restore it to normal width and make it readable again.

You can also display the Start menu at any time by pressing Ctrl-Esc.

Start menu the menu that is called up by the START BUTTON in the corner of the screen under Microsoft Windows. It leads to all the application software that is installed on the computer. To edit or modify the Start menu, open it with the right mouse button rather than the left button.

startup folder a FOLDER under the Windows START MENU containing programs that are to be run automatically when Windows starts up or when a user logs on.

starvation in MULTITASKING, a situation where a task can never finish because it can never get a necessary resource, such as a large block of memory. The operating system should detect such tasks and do its best to allocate the resources that they need. See MULTITASKING.

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