Barrons Publishing Dictionary of Computer and Internet Terms 10th

The human eye normally resolves about 150 lines per inch at normal reading distance, but a person examining a page critically can distinguish two or three times this much detail.

The resolution of a screen is given as the total number of pixels in each direction (e.g., 1024 × 768 pixels across the whole screen). The equivalent number of dots per inch depends on the size of the screen. Present-day video screens resolve about 100 dots per inch; they are not nearly as sharp as ink on paper.

A big advantage of draw programs, as opposed to paint programs, is that they can use the full resolution of the printer; they are not limited to printing what they display on the screen. However, some paint programs can handle very detailed images by displaying only part of the image at a time. See DRAW PROGRAM; PAINT PROGRAM; VECTOR GRAPHICS.

resource

1.anything of value that is available for use. Resources can refer to computers on a network, preallocated memory blocks in an operating system, or money in a budget.

2.a modifiable part of a program, separate from the program instructions themselves. Resources include menus, icons, and fonts.

resource leak see LEAK.

restart (in Windows) to REBOOT.

restore to make a window go back to its previous size after being minimized or maximized. In Windows, the restore button is to the right of the minimize button on the title bar and alternates with the maximize (fullscreen) button. Or, right-click the application’s icon on the taskbar; the top choice of the pop-up menu is “Restore.”

See also MAXIMIZE; MINIMIZE; WINDOW.

FIGURE 218. Restore button

retouching the alteration of a digital image to change its content, e.g., by removing visible blemishes on the skin of a person in a portrait. See PHOTOPAINT PROGRAM. Because they are so easily retouched, digital images are not usable as evidence (in science or in courtrooms) unless their authenticity can be proven. Retouching is different from image processing, which involves applying a uniform transformation to the entire image to enhance the visibility of information already contained in the image.

retrocomputing the hobby of preserving old computer technology, either by maintaining the machines themselves or by emulating them on newer equipment. See Figure 219.

FIGURE 219. Retrocomputing: a 1981 computer emulated under Windows 2000

return

1.the keyboard key that transmits ASCII code 13 (CR), normally the same as the Enter key. See CR.

2.to give a value as a result of a computation. For example, in many programming languages, sqrt(2) returns the square root of 2.

Returning a value is not the same as printing it out; returning a value makes it available for further computation, as in sqrt(2)+3.

3.in C and related languages, the statement that causes the computer to exit a function or subroutine and return to the program that called it. For example, return x; means “exit, returning the value of x as the value of the function,” and return; means “exit, returning no value.”

Return key the key on a computer keyboard that tells the computer that the end of a line has been reached. On most keyboards the Return key is marked Enter. On IBM 3270 terminals, the Return and Enter keys are separate.

reusable components pieces of software that can be used in other programs. For example, Java classes are reusable; they can be used by programs other than the one for which they were originally created.

reverse (in graphics) to replace white with black and black with white. A reversed block of type can be a dramatic design element—however, legibility can become a factor. A large block of reverse text is difficult to read. Typefaces with hairline strokes do not reverse well. The letters may spread and fill in if the font size is too small. Always evaluate a proof of reverse type carefully.

Type can also be reversed out of a color or a tint. Check that there is enough contrast between the type and the background for the text to be read.

FIGURE 220. Reversed type

reverse engineer to find out how something works by examining and disassembling the finished product.

reverse Polish notation see POLISH NOTATION.

revert to reload from disk a previously saved version of a file, losing all intermediate changes. Revert is therefore a super-undo command. Save your file before attempting a potentially dangerous command (search and replace or applying a filter), and you will have the option of reverting to the older file in case something goes wrong.

rewrap See REFLOW.

REXX a programming language used to write procedures that contain operating system commands. REXX is used in OS/2 .CMD files, IBM PCDOS 7.0 .BAT files, and some IBM mainframe operating systems.

Compare AWK; PERL.

RF (radio-frequency) a frequency in the range that is typical of radio waves, approximately 0.5 to 2000 megahertz. Contrast AF.

RFC

1.(radio-frequency choke) an inductor (coil) designed to keep high-fre- quency signals from flowing into power supply lines and other interconnections. See RFI PROTECTION.

2.(Request For Comment) one of numerous documents defining the standard for the Internet. All are supposedly unofficial, although most are followed universally. For example, RFC 822 specifies the format for E-MAIL messages in transit. RFCs are available online at www.cis.ohio-

state.edu/hypertext/information/rfc.html and other sites.

RFI protection protection of electronic equipment from radio-frequency interference.

Computers use the same kind of high-frequency electrical energy as radio transmitters. This often causes RFI (radio-frequency interference), also called EMI (electromagnetic interference). All computers interfere with nearby radio and TV reception to some extent, and sometimes the problem is severe. On rare occasions, the opposite happens — a strong signal from a nearby radio transmitter disrupts the computer, or two computers interfere with each other. See EMC.

Here are some suggestions for reducing RFI:

1.If possible, move the radio or TV receiver away from the computer, and plug it into an outlet on a different circuit.

2.Supply power to the computer through a surge protector that includes an RFI filter (see SURGE PROTECTOR).

3.Ground the computer properly (see SURGE PROTECTOR).

4.Use high-quality shielded cables to connect the parts of the computer system together. Make sure all cable shields and ground wires are connected properly. This is especially important for the monitor cable and the printer cable. If possible, wind the cable into a coil to increase its inductance.

5.Check that the computer has the appropriate approval from the FCC (Federal Communications Commission). Some computers are not approved for use in residential areas. See CLASS A; CLASS B;

FCC.

RFID (radio-frequency identification) the use of radio signals to recognize, from a few feet away, a tiny device (“RFID tag”) that can be built into price tags, library books, parking permits, ID cards, passports, or the like. RFID tags are even implanted under the skin of dogs for positive identification so that they can be returned to their owners if lost and found.

The RFID tag consists of an antenna and an integrated circuit, but no battery. The antenna picks up enough power from the transmitter that it can energize the integrated circuit and transmit a response, typically just an identifying number. The RFID tag itself contains almost no information; its usefulness comes from a database linking its ID number to other records.

RFP (Request For Proposal) an invitation to submit a price quotation, sales pitch, or grant proposal.

ribbon in the redesigned user interface of Microsoft Office 2007, the part of the screen containing tabs providing access to commands.

ribbon bar a row of small icons arranged just below the menu bar of a window. Each icon gives the user access to a frequently used command.

rich text text that contains codes identifying italics, boldface, and other special effects. WORD PROCESSING programs deal with rich text rather than plain ASCII or UNICODE text. See RTF. Contrast NONDOCUMENT MODE; TEXT FILE.

Rich Text Format see RTF.

right-click to CLICK the SECONDARY MOUSE BUTTON (usually the right button). In Windows, right-clicking the mouse will pop up an action menu that includes access to the “Properties” dialog for the selected object.

RIM (Research In Motion) the producer of the BLACKBERRY. Web address: www.rim.com.

RIMM (Rambus inline memory module) a memory module similar to a SIMM, but containing Rambus high-speed memory (RDRAM).

Ring 0, Ring 1, Ring 2, Ring 3 levels of privilege for processes running on a Pentium-family microprocessor. Normally, parts of the operating system run at Ring 0 (the maximum privilege level), and everything else runs at Ring 3.

rip

1.(from raster image processing) to convert a PostScript or vector graphics file to a bitmap file suitable for a particular output device, such as a color printer.

2.to convert an audio file from audio CD format to a digital format such as MP3.

RISC (Reduced Instruction Set Computer, pronounced “risk”) a CPU design with a small number of machine language instructions, each of which can be executed very quickly. The Sun Sparcstation and the PowerPC are examples of RISC computers. The opposite of RISC is CISC.

RISC architecture was developed for speed. A RISC computer can execute each instruction faster because there are fewer instructions to choose between, and thus less time is taken up identifying each instruction.

RISC and CISC computers can run the same kinds of software; the only difference is in what the software looks like in machine code. CISC is faster than RISC if memory access is relatively slow; the RISC machine has to fetch more instructions from memory than the CISC machine to do the same work. RISC is faster than CISC if memory access is very fast. See also CISC; COMPUTER ARCHITECTURE; POWERPC.

riser a small circuit board inserted perpendicularly into the motherboard, containing slots for cards. Compare DAUGHTERBOARD. See also CARD (definition 2); MOTHERBOARD.

riser-rated (describing cable) suitable for use inside walls and in open areas but not in places where air circulates, such as above suspended ceilings. Riser-rated cable is fire-resistant but can give off noxious fumes when overheated. Contrast PLENUM-RATED.

river a series of white spaces between words that appear to flow from line to line in a printed document, like the white patch in the following example. Rivers result from trying to justify type when the columns are too narrow or the available software or printer is not versatile enough. See

JUSTIFICATION.

Quo usque tandem abutere, Catilina, patientia nostra? quamdiu etiam furor iste tuus nos eludet?

RJ-11 the 4-pin modular connector used to connect telephones and modems to the telephone line (see Figure 221, right). One RJ-11 con-

nector can support two telephone lines, one on the inner pair of pins and one on the outer pair.

RJ-45 the 8-pin modular connector used on the ends of 10base-T and 100base-T cables (see Figure 221, left); it resembles a 4-pin telephone connector but is wider. The color code for wiring RJ-45 connectors is shown in Table 13. See also CATEGORY 3 CABLE, CATEGORY 5 CABLE.

FIGURE 221. RJ-45 connector (left ) and

RJ-11 connector (right )

TABLE 13

RJ-45 CONNECTOR WIRING FOR 10BASE-T and 100BASE-T NETWORKS

Pins are numbered from left to right as seen with the plug pointing away from you, contacts up.

Note that one twisted pair (on pins 3 and 6) goes to nonadjacent pins.

Normal cables are T568A or T568B at both ends. A crossover cable is T568A at one end and T568B at the other.

RL abbreviation for “real life” in e-mail and online games.

rlogin (remote login) the UNIX command that allows you to use your computer as a terminal on another computer. Unlike telnet, rlogin does more than just establish a communication path: it also tells the other computer what kind of terminal you are using and sends it your user name.

RMI (Remote Method Invocation) technique for calling a method in a Java class located on a machine (such as a web server) different from the machine (such as the browser client) on which the current application is running.

rms (root-mean-square) the most common method of measuring the voltage of an alternating current; the square root of the mean of the square of the instantaneous voltage. This method of measurement is used because power (wattage) depends on the voltage squared; thus, 120 volts AC rms will light a light bulb to the same brightness as 120 volts DC. With a sine wave, the rms voltage is 0.707 × the peak voltage or 0.353× the peak-to- peak voltage. Contrast PEAK; PEAK-TO-PEAK.

roaming user profiles in Windows NT and its successors, a facility that allows each user’s desktop, account information, and files to be stored on a server so that they are accessible from any networked PC at which the user logs on. See PROFILE (definition 2).

robot

1. a computer that moves itself or other objects in three-dimensional space under automatic control. Robots are now widely used in manufacturing. See also

2.(slang; also bot) a computer program that performs a human-like communication function such as replying to E-MAIL or responding to messages in a NEWSGROUP. See also DAEMON.

3.a program that searches the World Wide Web, gathering information for indexing in search engines. See CRAWLER; SEARCH ENGINE; SPIDER. See also META TAG.

robust reliable even under varying or unforeseen conditions. Contrast BRIT-

TLE.

Rock Ridge a compatible extension to the ISO 9660 CD-ROM format, allowing longer filenames, commonly used in UNIX systems. On computers that do not support Rock Ridge format, the discs can still be read, and the files still have unique names, but the names are shortened.

Compare JOLIET FILE SYSTEM.

ROFL online abbreviation for “rolling on the floor laughing.” See also

ROTFL.

RoHS (Restrictions on Hazardous Substances) a directive adopted by the European Community and effective on July 1, 2006, requiring the almost complete elimination of lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls, and polybrominated diphenyl ethers in electronic equipment sold in Europe. Similar restrictions are being adopted elsewhere.

The main effect of RoHS is to mandate the use of lead-free solder and to eliminate nickel-cadmium batteries. See NICD; SOLDER.

<body>

<h1>Example of a Mouse Rollover with a changing image</h1> <ul>

<li><a href=”#choice1” onMouseOver=”rollOn(1); return true;” onMouseOut=”rollOut(); return true;”> Choice 1 </a>

<li><a href=”#choice2” onMouseOver=”rollOn(2); return true;” onMouseOut=”rollOut(); return true;”> Choice 2 </a>

</ul>

<img name=”image1” height=”200” width=”300” src=”default_image.jpg”>

<a name=”choice1”><h2>Here is choice 1</h2></a> Here is some text for choice 1.<br>

<a name=”choice2”><h2>Here is choice 2</h2></a> Here is some text for choice 2.<br> </body></html>

See also HTML; JAVA; JAVASCRIPT; RIGHT-CLICK.

ROM (Read-Only Memory) a computer memory that contains instructions that do not need to be changed, such as permanent parts of the operating system. The computer can read instructions out of ROM but cannot store new data in it. See also CD-ROM; EPROM; PROM.

ROM BIOS see BIOS.

roman the kind of type that books are normally typeset in, as opposed to italics or boldface. The type you are reading now is roman type. See

TYPEFACE.

root the account name used by the system administrator under UNIX. (From ROOT DIRECTORY.)

root directory the main directory of a disk, containing files and/or subdirectories. See DIRECTORY.

root hub the set of USB ports located inside a computer. See USB.

root-mean-square see RMS.

rootkit a software package that tampers with the innermost kernel of an operating system, concealing its presence and its effects unusually well because it can intercept any attempt to detect it.

Originally, a “root kit” was a set of cracking programs designed to run under the ROOT (system administrator) account of UNIX while leaving no trace of their presence.

Today, most rootkits are for Windows. The only sure way to detect them is to boot an entirely separate operating system, such as a copy of