Glossary of Computer Terms—R

Glossary of Computer Terms—R

R

RAID: Redundant Array of Inexpensive Disks. A method of spreading information across several disks set up to act as a unit, using two different techniques.

RAM: Random Access Memory. One of two basic types of memory. Portions of programs are stored in RAM when the program is launched so that the program will run faster. Though a PC has a fixed amount of RAM, only portions of it will be accessed by the computer at any given time. Also called memory.

RAM DISK (DISK EMULATOR): A portion of a hard drive configured to emulate a RAM. It accesses information quickly, but its data must be saved in a non-volatile memory for future use. Otherwise, the information is lost when power is removed.

RANDOM ACCESS: A technique of accessing (reading) a word of data from a memory structure by the CPU. Since a word in the memory can be accessed directly, the time required is independent of its location (address) in the memory structure. It is sometimes called a “direct access” method.

RANDOM ACCESS MEMORY (RAM): A volatile, semiconductor storage structure that accesses temporary data with a random or direct accessing method. It is more accurately referred to as “erasable read/write” memory. Data in this memory can be read by the CPU, edited, altered, erased, or new information written over existing data by computer commands. Its data must be saved for future access by writing it into a non-volatile memory. See NON-VOLATILE MEMORY and VOLATILE MEMORY.

READ-ONLY MEMORY (ROM): A semiconductor memory whose data cannot be erased, or overwritten; it can only be accessed (read) for use by the CPU. The data in a ROM is of a permanent nature and is programmed by the ROM manufacturer. In many cases, its programmed information identifies the dedicated function of a computer. A ROM can also be in the physical form of a module (tape or disk) that is plugged into a computer to change its operation from one program to another.

REALAUDIO: This is a method of playing sounds invented by Rob Glasser that creates a buffer between the supplying server and your computer. The file is played without downloading it completely.

REAL TIME: This is method of processing data the moment it is received. Batch mode is a term used for a mainframe computer dealing with data when it has the time.

REAL-TIME DATA: Time-dependent data processed by a computer whose output data is capable of controlling other time-related events, such as traffic control. Real time is the actual time it takes for an event to occur.

REBOOT: To restart a computer. In DOS, you can reboot by pressing the Alt, Control and Delete keys simultaneously. This is called a warm boot. You can also perform a cold boot by turning the computer off and then on again.

      On Macs, you reboot by selecting the “Restart” option from the Special menu.

REFRESH: Generally, to update something with new data. For example, some Web browsers include a refresh button that updates the currently display Web pages. This feature is also called reload. To recharge a device with power or information. For example, dynamic RAM needs to be refreshed thousands of times per second or it will lose the data stored in it.

      Similarly, display monitors must be refreshed many times per second. The refresh rate for a monitor is measured in hertz (Hz) and is also called the vertical frequency, vertical scan rate, frame rate or vertical refresh rate. The old standard for monitor refresh rates was 60Hz, but a new standard developed by VESA sets the refresh rate at 75Hz for monitors displaying resolutions of 640x480 or greater. This means that the monitor redraws the display 75 times per second. The faster the refresh rate, the less the monitor flickers.

REGISTER: A temporary storage unit for quick, direct accessibility of a small amount of data for processing. Most computers include a set of internal registers that can be accessed more quickly than the system’s main memory.

RESIDENT SOFTWARE: The program(s) residing in the main memory of a computer system. For convenience of operation, several software programs can reside in RAM after the computer is turned on and booted, and they can be accessed quickly from within another program.

RESOLUTION: Refers to the sharpness and clarity of an image. The term is most often used to describe monitors, printers, and bit-mapped graphic images. In the case of dot-matrix and laser printers, the resolution indicates the number of dots per inch. For example, a 300-dpi (dots per inch) printer is one that is capable of printing 300 distinct dots in a line 1 inch long. This means it can print 90,000 dots per square inch.

RS-232-C: Identifies an interconnection standard for serial operation. It specifies the configuration and type of connectors in the computer’s serial I/O port(s) and peripheral serial port(s).

ROUTER: A network device that enables the network to reroute messages it receives that are intended for other networks. The network with the router receives the message and sends it on its way exactly as received. In normal operations, they do not store any of the messages that they pass through. 
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