RAD
Rapid Application Development. Speedier development of programs. This is accomplished by several methods.
  • A team of expert programmers can speed development.
  • Programmers can utilize code from previous projects or code premade by third-party developers.
  • Developers can utilize "wizards". Wizards write a bulk of the code but can be customized for specific needs.
  • Programmers can use more modern computer programming languages that facilitate RAD with OOP (Object Oriented Programming),  automatic code completion (little features that fill in statements, properties, and arguments or even provide lists of context sensitive choices, statements, functions, and values), etc.
  • Developers can make prototypes right away and patch the prototypes till they work -- especially if the application will be short lived.  
Radio Frequency IDentification
See RFID.
RAID
Redundant Array of Inexpensive Disks. Multiple physical hard disks that cooperate together for purposes of speed and/or fault tolerance. Fault tolerance means that if one of the disks fails, the system can continue with no data is lost. See also my article on RAID.
RAM
1) Randomly Accessed Memory. Data that can be accessed without having to pass through the data before or after it. This is analogous to a dictionary in that you can open to any page. Examples include floppy disks, hard disks, DIMMs, and CD-ROMs. See also SAM.
 
2) RAM also refers to the physical circuit boards and memory modules used in processing memory. RAM is used in the main memory of computers, in printers, video cards, etc. RAM comes in two major types, DRAM (Dynamic RAM) and SRAM (Static RAM). Each in turn comes in different variations. EG:  SIMM, DIMM, EDO DRAM, BEDO DRAM, MDRAM, SGRAM, VRAM, WRAM, and RDRAM. The third type of RAM is MRAM (Magnetoresistive RAM). See MRAM.
 
The RAM usually comes in the form of chips that fill groups of sockets, called banks, on the motherboard. Each bank consists of 1, 2, or 4 sockets and each socket must be filled with the same size of RAM. EG: A computer with a bank of RAM with 2 sockets holding 2 chips, each of which is 32 MB.
Random Access Memory
See RAM.
range
In spreadsheets, this refers to a block of cells. EG: A range might be A1:C10, i.e. the cells in the intersection of columns A thru C and rows 1 thru 10. A range can also be named, eg the range Sales may refer to Sheet1!A1:C10 , i.e. the range A1:C10 on Sheet1.
Rapid Application Development
See RAD.
RAS
(1) Remote Access Server. Any server which provides access to users who are not part of the LAN or WAN. Such users typically dial in, eg a user with a browser and  modem who connects to his ISP. If the user has some sort of dedicated connection, then that connections is more like a WAN extension.

(2) Remote Access Services. Features of the Windows NT OS that enables users to log into a NT LAN using a modem, X.25, or a WAN link. RAS cooperates with major network protocols including TCP/IP, IPX, and NetBEUI. Remote users would use a PPP client software or RAX client software, both of which come with most varieties of Windows.
raster images
Graphics rendered in pixel by pixel format, eg BMP, GIF, PIC, and TIFF. Paint programs usually deal with rasterized graphics. In contrast, vector objects are graphics rendered in a format that described by mathematical equations. Common tools for making rasters include Adobe's Photoshop, Deneba's Canvas, Jasc Software's Paint Shop Pro, Microsoft's Image Composer, and Macromedia's Director.
Raster Image Processor
See RIP.
RBAR
Row by agonizing row. An operation that goes does one row at a time as opposed to a set of rows.
RCA
See TV.
RDBMS
Relational DataBase Management System. See relational database.
RDF
Resource Description Framework. A W3C standard which provides "a lightweight ontology system to support the exchange of knowledge on the Web". RDF uses XML to exchange metadata about websites (and their content). Such metadata includes site maps, document update dates, and keywords usable by search engines.
RDF Site Summary
See RSS.
RDRAM
Rambus Dynamic Random Access Memory. A memory circuit board developed by Rambus, Inc., ca. 1997. RDRAM is a type of DRAM that can support data transfers up to 600 MHz. Since Intel licensed RDRAM, it should become popular. Also Rambus is supposedly working on nDRAM, which can go up to 1600 MHz.
RDS
Remote Data Service. A Microsoft product previously released as ADC (Advanced Data Connector) but was incorporated into ADO (AcitveX Data Objects). RDS allows you to move data from the server to a client application or Web page, let the manipulate the data, and return the updates to the server, all in a single round trip.
Read Only Memory
See ROM.
record
The basic unit of information in a database. It is a row in table.
recordset
Aka result set. A virtual table that is the result of a select query. It works just like a real table: it can be browsed, selected, sorted, and printed. In contrast, an action query, which deletes, inserts, or updates data but does not produce a recordset.
recursive
A recursive pattern is where one step is dependent upon the outcome of a previous step. In programming, a recursive function produces a result and then calls itself while passing the result as a parameter.
Red Green Blue
See RGB.
Redmond, WA
Microsoft's HQ.
Reduced Instruction Set Computing
See RISC.
reengineering
The rethinking of the way goals are reached so as to improve efficiency drastically instead of just a little bit.

Mike Hammer's 7 rules of reengineering:
>1. Organize around outcomes, not tasks.
2. Have those who use the output of the process perform the process.
3. Subsume information-processing work into the real work that produces the information.
4. Treat geographically dispersed resources as if they were centralized.
5. Link parallel activities instead of integrating their results.
6. Put the decision point where the work is performed, and build control into the process.
7. Capture information once, at the source.
refactoring
(1) Changing code without changing what it does. This process tidies up code, removes excess code, unifies identifiers, catches unhandled exceptions, standardizes, etc.

(2) See XP.
referential integrity
In databases, this assures the integrity and relationship of data in one table with data in another table.
register
(1) A storage area in the computer that accounts for all the data in the system. The size of data chunks in the data determines the level of the computer. EG: Windows 3.1 is 16 bit, but Windows NT is 32 bit. Only low level languages access the register. High level languages are first compiled so that they can access the register.
 
(2) To provide the manufacturer with information when you obtain one of their products. This facilitates customer support and reduces piracy.
Registry
A database internal to the Windows operating system that has the configuration settings on the system. This includes user and account info, hardware setting, and application and document settings. The Registry can be modified with the Registry Editor (regedit.exe).

The Registry stores data in a hierarchical hierarchical tree of attribute-value pairs. The Registry has nodes, each of which can contain subkeys and data entries called values. The Registry has six nodes:
  • HKEY_CLASSES_ROOT File associations and OLE information.
  • HKEY_CURRENT_USER Preferences for current user of the machine.
  • HKEY_LOCAL_MACHINE Settings for hardware, operating system, memory, and applications on the machine.
  • HKEY_USERS Preferences for all users of the machine.
  • HKEY_CURRENT_CONFIG Settings for display and printers.
  • HKEY_DYN_DATA Performance data.
Registry values are one of seven types:
  • REG_BINARY Raw binary
  • REG_DWORD A 32-bit number
  • REG_SZ A null-terminated string.
  • REG_MULTI_SZ An array SZ's terminated by two null characters
  • REG_EXPAND_SZ An SZ that contains unexpanded references to environment variables, eg %PATH%
  • REG_LINK A Unicode symbolic link
  • REG_NONE Undefined value type
The Registry replaces the old INI files although INI files are still supported for backwards compatibility. The Registry is usually affected when a program is installed. The Registry is also affected with the Control Panel or other utilities. In networks, the Registry may even be kept on a server for centralized administration.
relational database
A database which collects related data into tables/files/relations/entities on one and only one subject. Each table is itself a collection of records and fields. The different tables have relationships with other tables. The data can be accessed and reassembled without reorganizing the tables. The tables are often related to each other in some manner usually consistent with the branch of mathematics called Set Theory. The relational databases were invented by E.F. Codd at IBM in 1970. Many relational databases utilize a database language called SQL.
Relational DataBase Management System
See relational database.
relationships
In databases, a relationship describes how one table/file/relation/entity of data may be joined or related to another.
 
One-to-one: one row (record/instance) ties to one row in another table, eg a table of students joined with a table of students' health records: each student has only one health record.
 
One-to-many: one row in the parent table ties to one or more rows in the child table, eg a table of students joined with a table of tickets: each student may have multiple tickets.
 
Many-to-many: one or more rows tied to one or more rows in another table, eg a table of students joined with a table of classes: each student may have multiple classes and each class may have multiple students. Many-to-many relationships are often accomplished by creating a separate third intersection/junction table that acts as a child table to the two parent tables.

Relationships are often graphically displayed as boxes (representing the tables) connected by lines (representing the joins). These representations are known as ERD (Entity Relationship Diagrams). There are frequently little symbols on or along the lines representing the join type. See join.
Remote Access Services
See RAS.
Remote Data Service
See RDS.
Remote Method Invocation
See RMI.
Remote Monitoring
See RMON.
Remote Procedure Calls
See RPC.
removable storage
Computer storage memory that can be switched out easily. EG: A floppy disk is removable storage but the hard drive is not considered to be removable storage. See also my article on removable storage.
repeater
A repeater can extend the reach of a network segment. A repeater will recognize an attenuated (weakened) baseband signal, clean it up, strengthen it, and then send it along to another network segment. A repeater operates in the OSI Physical Layer. See also my article on Portal Devices.
registration mark
Small, usually geometric marks, placed at key points that help to align several pieces together, especially different layers or plates.
registry
The repository for all configuration information for the Windows OS. It is made up of the files system.dat and user.dat, both of which are stored in the Windows home directory (usu. c:\windows). Backups of these files are in the same directory but with the extension .dao. DO NOT FOOL WITH THE REGISTRY UNLESS YOU ARE SURE OF WHAT YOU ARE DOING.
repeater
A network segment can transmit data over a fixed distance before the signal degrades too much. This distance depends on the media type, eg UTP media has a range of 100 m whereas thick coaxial cable has a range of 500m. A repeater can extend the reach of a network segment. A repeater will recognize an attenuated (weakened) baseband signal, clean it up, strengthen it, and then send it along to another network segment. A repeater operates in the OSI Physical Layer. As a rule of thumb, no more than three repeaters should be used to extend the distance between nodes in an Ethernet LAN. Otherwise the system may experience propagation delay because of the pauses at the repeaters. Note that a repeater is for digital baseband signals, whereas an amplifier is for analog broadband signals.
replication
Aka mirroring. Replication ensures that all replicates automatically and immediately update all other replicates of the same part. This is good for times when the data must be local and current.
Representational State Transfer
See REST.
Request For Comments
See RFC.
resolution
The level of detail of an image. The hard copy output resolution is measured in lines per inch (lpi). EG: Typically newspapers are 75 lpi, magazines are 150 lpi, and fine art books are 300 lpi.

The resolution of computer images is measured in dots per inch (dpi) or pixels per inch (ppi). A rule of thumb is to have a computer image's ppi to be roughly 1.5 to 2 times the printing output's lpi. A higher resolution is not always better, especially for small images or images on the web.

The optical resolution is the resolution of an original computer image. Depending on the image file type, if the original computer image is shrunk, its resolution may increase, or if the image is enlarged, its resolution may decrease.

To avoid the loss of resolution, the original image can be created with a higher resolution. EG: If you are going to scan an image and you know that you will double the image area, then scale to 200% and scanner will scan at double the resolution and double the output image area. Alternatively, to compensate for the loss of resolution, an image's resolution may be interpolated, i.e. enhanced with software.

See also monitor.
Resource Description Framework
See RDF.
Resource Reservation Protocol
See RSVP.
REST
Representational State Transfer. Software architecture that use principles derived from a paper by Roy Fielding, one of the principal authors of the HTTP specification. The four principles are:
  • Stateless client/server protocol. Usually HTTP.
  • Well-defined operations that apply to resources. Usually HTTP's PUT, GET, POST, and DELETE.
  • Universal syntax for resource identification. Usually a URI (Universal Resource Identifier) like an URL.
  • Use hypermedia for information and state-transitions. Usually HTML, XHTML, or XML.
Usually REST (which relies on a multitude of URI "nouns" and parameterized queries) is seen as the opposite of RPC (Remote Procedure Calls), like most SOAP based Web Services (which rely on a multitude of "verbs"). See also Web Services.
Return On Investment
See ROI.
Reverse DNS
Reverse DNS resolves IP addresses to relatively user-friendly FQDNs (Fully Qualified Domain Names). See also DNS.
Reverse Polish Notation
See RPN.
revision control
Aka version control software (VCS); reversion control software (RCS). Managing documents, software, projects that undergo change, especially when it is revised by multiple people in different locations. People do this manually with "Save As". Google Documents does this automatically. Some RCS is centralized (or client-server) but others are distributed. Some RCS can be plugged into different integrated development environments (IDE) such as Micorosoft Visual Studio. See these related links:
RFC
Request For Comments. An ongoing note file maintained by the IETF since 1969. RFC notes are about the Internet. An RFC note can be submitted by anyone and each RFC note has a unique number. EG: RFC 822 [§] has basic standards for ARPA Internet Text Messages.
RFID
Radio Frequency IDentification. The technologies that use radio waves to automatically identify items that have been tagged with an RFID chip. An RFID system consists of an interrogator (aka reader) that sends out electromagnetic waves (in the radio frequency) that couples with a coiled antenna on an RFID chip. The magnetic field created is used by passive chips to send an identifying signal back to the reader. Active chips  have batteries and can send a stronger signal further. Passive chips can be as small as 0.3 mm. See also RFIDJournal.com.
RGB
Red Green Blue. The three hues that compromise monitor screen images. Each hue or color channel has 256 intensity or saturation levels. The range of colors that RGB can produce exceeds that of CMYK.
Rhapsody
The yellow box. An upcoming OS being developed by Apple. Like Windows NT, it is a 32 bit OS that will support symmetric multiprocessing and preemptive multitasking. Rhapsody is UNIX based, will run the Mac OS (the blue box), and a Java OS. Plus, this Rhapsody will run on Macs or PCs!
Rich Site Summary
See RSS.
Rich Text Format
See RTF.
right click
To click on the desired item or area with the right mouse button.
RIP
(1) Raster Image Processor. Hardware or hardware/software that converts vector (geometrically described) images into rasterized (drawn dot by dot) images. Many graphic files are actually vector images.

(2) Routing Information Protocol. A protocol for managing the routing info of a LAN (Local Area Network) and submitting it to an ISP (Internet Service Provider). A gateway host with RIP and a router has a routing table which IDs everyone on the LAN. RIP sends this routing table to its neighbor host (usually at the ISP). Since RIP sends this every 30 seconds, RIP is only good for smaller LANs.
ripper
An application that converts CD music into computer usable formats like .mp3, .wav, and .ra (RealAudio). These files can then be played using the ripper, RealAudio, MS Media Player 6, etc.
RISC
Reduced Instruction Set Computing. A processor faster than CISC but not as common. RISC achieves its power by reducing the number of instructions in comparison to CISC. The RISC can then focus on processing with speed. The PowerPC uses a RISC chip. Many UNIX servers run on RISC processors.
risk analysis
Analysis which identifies and asses factors that might jeopardize the ROI as well as how to deal with the risks.
RJ-XX
Registered Jack. Jacks registered with the US FCC (Federal Communications Commission). The typical telephone and LAN media. Click here for an image of RJs.

An RJ-11 jack has 4-6 wires and can handle one to two telephone channel(s). This is common for phones and faxes.

An RJ-45 jack has eight wires and is used for Ethernet LANs. See 10BASE-X.

There are many variations of RJ-XX including ICX, IDC, 11C/W, 14C/W, 14X, 15C, 17C, 18C/W, 2DX, 2EX, 2FX, 2GX, 2HX, 2MB, 21X, 25C, 26X, 27X, 4MB, 41M, 41S, 45M, 45, 48C , 48H, 48M, 48S, 48T, 48X, 61X, M8, etc. See also connector.
RLE
.rle. Run Length Encoding. A compression method that BMP-format files support. RLE converts portions of data that consecutively repeats a character into the character and a number indicating the number of repetitions. This method works best with files with great expanses of the same color.
RMI
Remote Method Invocation. Sun's protocols for distributed Java objects. It is akin to Microsoft's DCOM and IBM's DSOM except that the others support objects created in any language.
RMON
Remote MONitoring. A network monitoring protocol that gathers information about the network. RMON incorporates SMNP as well as gathering even more information. RMON 1 watches the physical layer and RMON 2 watches the traffic in the network layer.
robot
(1) Device that performs tasks either independently or by remote control. The word is derived from the Czech word, robota, which means compulsory labor.

(2) In science fiction robots come in degrees of sentience, from emotionless automatons performing tedious labors, to highly sophisticated beings that obey the Rules of Robotics developed by Isaac Asimov: (1) A robot may not injure a human being, or through inaction, allow a human being to come to harm. (2) A robot must obey the orders given it by human beings except where such orders would conflict with the First Law. (3) A robot must protect its own existence as long as such protection does not conflict with the First or Second Law.

(3) In computers robots are programs that take themselves to different sites on the Internet to gather information for their master. Since they can spread out within an entire web site, the robots are also called spiders.

Most robots follow the convention of first looking for a file called robots.txt in the main directory. The robots.txt file tells the robot which directories and files should not be spidered. The robots.txt file is a text file that contains this UNIX format:
User-agent: *
Disallow: /
Disallow: /membersonly
# Comments follow pound signs
The first portion describes which robots the file is referring to (in the example above the * indicates all robots). The second portion describes which files are disallowed (in the example above the / indicates the root directory).

Alternatively, an HTML file can use meta tags in the head like the following. Some folks say to use a meta tag instead of a robots.txt file because the robots.txt file basically tells the hackers where the good stuff is!
<meta name="robots" content="noindex">
<meta name="robots" content="nofollow">
<meta name="robots" content="noindex, nofollow">

See also RobotsTxt.org.
ROFL, ROTFL
Rolling On The Floor Laughing.
ROI
Return On Investment. A common business term which refers to the the return on an endeavor. The return is typically profits or cost savings, but may be measured in market revenue share, developed infrastructure, sales positioning, product branding, or any other objective.

ROI estimates should also include some risk analysis to identify and asses factors that might jeopardize the ROI as well as how to deal with the risks.
ROM
Read Only Memory. Storage memory that can be read but not written to. When a computer is first turned on, one of the first things it does is access a ROM chip for instructions. Another common instance of ROM is found with CD-ROMs. Note that ROM is usually RAM but RAM may or may not be ROM.
 
Some variations of ROM chips include PROM (Programmable ROM), EPROM (Erasable PROM), and EEPROM (Electronically EPROM).
rot13
ROTate 13 places. Simple Caesar cipher encryption for the 26 letters of English where the shift is by 13. 13 works differently from any other Caesar cipher on 26 letters because the same 13 shift will encode as well as decode.
ABCDEFGHIJKLMNOPQRSTUVWXYZ
NOPQRSTUVWXYZABCDEFGHIJKLM

See also rot13.com.
router
A router connects two or more network segments at the OSI Network Layer. A router is either:
  • A device, with multiple ports, specifically for routing packets.
  • A computer, with multiple NICs, that has routing software.
Just as a bridge makes a bridging table out of MAC addresses in the Data Link Layer, a router makes a routing table out of network addresses in the OSI Network Layer. Because network addresses have more information than MAC addresses, a router is more powerful than a bridge.

See also my article on Portal Devices.
Routing Information Protocol
See RIP.
RPC
Remote Procedure Call. A form of middleware common in the mid 1980s. One program may invoke processes elsewhere on the network.
RPN
Reverse Polish Notation. Aka postfix notation; stack operation; LIFO (Last In First Out). A method of mathematical notation created by Charles Hamblin in 1957 and based upon the Polish notation created by Jan Łukasiewicz in 1920.
  • In regular notation (aka infix notation), operators are usually placed between operands. EG: 2 + 3. EG: (1 + 3) * 5.
  • In Polish notation (aka prefix notation), operators are usually placed before operands. EG: + 2 3. EG: * + 1 3 5.
  • In RPN (aka postfix notation), operands are usually placed before operators. EG: 2 3 +. EG: 1 3 + 5 *.
The great thing about RPN is that calculations proceed from left to right and in theory you never need parentheses. There are also no "hidden states". Computers using RPN make very efficient use of storage memory. The great Forth programming language makes great use of RPN.
RS-232, 422, 423 , 485
See serial port.
RSA
Rivest, Shamir, and Adelman. RSA was invented by RSA who formed RSA Data Security. It is public key encryption with an algorithm based on the difficulty of factoring very large numbers. RSA encryption is built into Netscape Navigator and Microsoft Internet Explorer. The US has restricted its exportation to other countries.
RSS
RDF Site Summary, Rich Site Summary, Really Simple Syndication. An XML document which is simply a list of weblog posts of a particular blog or portion of a blog. There are many variations and versions of RSS but most applications that consume RSS can input all the different variations. There is no standard file extension for RSS but .xml, .rss, and .rdf are commonly used. A blog makes an RSS of its content available for syndication, i.e. so that the content can be consumed by applications such as news sites, search engines, or RSS aggregators.

See also my section on Blogs.
RSVP
Resource ReServation Protocol. A protocol which lets a user request a level of QoS (Quality of Service) from each RSVP enabled router along the way to and from the source. If a router along the way can't make the request then the user will get an error message.
RTF
.rtf. Rich Text Format. A common format into which most PC, Mac, or UNIX WPs can Save As.... It stores text as well as formatting information, eg font, font size, character style, indentations, and special characters, but does it in a file containing only ASCII characters. This format is easily converted into HTML.
RTFM
Read The F------ Manual.
Run Length Encoding
See RLE.
runtime error
Any error that causes a program to stop running. A syntax error is a runtime error due to program coding that does not follow proper syntax. A logic error is made when the program has proper syntax but does not produce the desired result due to improper reasoning by the programmer.

Typical runtime errors:
  • Network errors: network resources or drives that fail.
  • Floppy disk errors: ejected disks, improperly formatted disks, or bad disk sectors.
  • Printer errors: offline printers, out of paper, or unavailable.
  • Overflow errors: too much information to be printed or drawn.
  • Out of memory errors: not enough memory or resources.
  • Clipboard errors: snag in transferring data to and/or from the clipboard.
  • Other errors: Misc. syntax or logic errors previously undetected, eg typos.

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