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Glossary: R
- radiosity
- A software technique to simulate the effects of light diffusion and add shading to objects in computer graphic images that seem sharper than reality.
- random access memory (RAM)
- The primary internal storage device of a personal computer, where programs and data are kept during processing.
- range
- A set of adjacent row or column cells treated as a unit, for example, to be placed in a function to get a sum of cell values in a column. Specifying a range of cells eliminates the need to list all of them individually.
- rapid applications development (RAD) tools
- Programming environments with objects, graphical interfaces, and superior debugging features for rapid prototyping of applications. Both Delphi and Visual BASIC fall into this category.
- raster
- A term for the horizontal lines of pixels on a TV or CRT screen, refreshed at a rate of 30 times a second to display an image on the screen.
- raster graphics
- A common method of presenting computer graphic images on a CRT, based on the technology of television, that uses an electron beam to excite phosphor dots (pixels) inside the CRT screen and make them glow.
- ray tracing
- An enhancement technique for computer graphics that simulates the effect of reflected light rays in a three-dimensional scene on a two-dimensional computer screen.
- read-only memory (ROM)
- Memory chip that permanently stores instructions and data. Because it can be read from but cannot have new information put into it, manufacturers store important control programs in ROM chips.
- real number
- A positive or negative number, including zero, that can be expressed with fractions, called floating point in computers because they are represented with a floating binary point similar to a decimal point.
- real time
- A term used to describe a computer application in which the delay between input of data and completed processing is negligible. When a computer presents results as soon as the data have been received, the process is called a real-time application.
- record
- A collection of related fields comprising one item in a data file, such as a complete book record in an on-line catalog.
- refresh buffer
- In vector graphics, hardware that renews a phosphor-coated display screen with an electron beam to maintain information that would otherwise flicker.
- relational (tabular) model
- A design used in database systems in which relationships are created between one or more flat files or tables based on the idea that each pair of tables has a field in common.
- rendering
- A general term for creating a ray-traced image.
- repetitive stress injury (RSI)
- A medical condition resulting in severe arm pain, thought to be caused by sitting long hours at computer keyboards.
- reporting
- The process of printing or displaying information contained in a database, often the last step in database management.
- resolution
- A term referring to the number of pixels on a computer screen. The higher the resolution, the better the characters or images on the screen appear.
- RGB (red-green-blue) monitor
- A term for a color monitor, with the letters of the name standing for the three primary additive colors that combine to make color images on the screen.
- RISC (reduced instruction set computing) chip
- A microprocessor chip with fewer and simpler instructions capable of performing complex tasks by combining simple instructions and reducing processing time.
- robotic machine
- A robot typically engineered with sensors and a gripper arm to carry out an automated industrial process.
- ruler line
- A section of some word processor screens for setting options such as margins, tabs, and spacing between lines of text, resembling a ruler in inches or centimeters.