| R:BASE |
A relational DBMS from Microrim, Inc., Bellevue, Washington.
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| RACF |
Resource Access Control Facility. A large system security program for IBM mainframes that checks passwords and prevents unauthorized users from accessing files.
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| rack |
A frame or cabinet for mounting computer components.
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| rack mounted |
Built to fit into a metal rack. Some computer components are rack mounted units.
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| RAD |
Rapid Application Development. A way of developing a system by completing a working part, implementing it, and adding more working parts every few months, instead of waiting to finish the entire project before putting the system into use. Otherwise, changes take place so fast in the computer industry that an application can be obsolete by the time it is implemented. Development tools such as visual programming and computer-assisted software engineering help with Rapid Application Development.
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| RAD tool |
Rapid Application Development tool. Software that speeds up the development of applications.
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| radio |
Wireless transmission of electric signals by way of electromagnetic waves, including the use of electromagnetic waves to transmit electric impulses that carry converted sound signals.
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| radio buttons |
A group of buttons on the computer screen of which only one
can be selected at a time (by clicking on it). Radio buttons are used a lot with interactive forms on World Wide Web pages.
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| radio frequency |
(RF). Electromagnetic frequencies in the range extending from below 3 kiloherz to 300 gigahertz, which includes radio and television transmission. These frequencies are above audio signals and below the frequencies of visible light.
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| radio frequency interference |
(RFI). Interference from high-frequency electromagnetic waves emanating from electronic devices.
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| radio-frequency fingerprinting |
An electronic fingerprint that makes it possible to identify a wireless handset by its unique radio transmission characteristics.
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| radiosity |
A more accurate but also more process-intensive technique than raytracing, that calculates patterns of light and shadow for rendering graphics images from three-dimensional models.
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| radiotelephone |
A device that sends telephone signals without wires, by means of radio waves.
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| radix |
- The base of a system of numbers; decimal numbers are radix ten, binary numbers are radix two, and hexadecimal numbers are radix sixteen. 2. The positive integer by which the value of one digit place must be multiplied to give the value of the next higher digit place; for example, in a decimal system, each digit place is multiplied by 10 to arrive at the value of the next higher digit place, so the radix is 10.
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| ragged left |
Text in which the left margin is not aligned.
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| ragged right |
Text in which the right margin is not aligned.
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| RAID |
Redundant Arrays of Independent Disks (Originally "Redundant Arrays of Inexpensive Disks"). The use of two or more disk drives instead of one disk, which provides better disk performance, error recovery, and fault tolerance, and includes interleaved storage techniques and mirroring of important data. This approach was developed by a research project at the University of California, Berkeley.
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| RAID |
Redundant Arrays of Inexpensive Disks. Comes in different levels 0,1,0+1,5, etc.
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| RAIDmark |
A benchmark program by DynaTek Automation Systems Inc., that measures the performance of RAID arrays. RAIDmark measures cache size, system overhead, and application-level performance. There are MS-DOS and Novell versions.
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| RAM |
Random Access Memory. The working memory of the computer. RAM is the memory used for storing data temporarily while working on it, running application programs, etc. "Random access" refers to the fact that any area of RAM can be accessed directly and immediately, in contrast to other media such as a magnetic tape where the tape must be wound to the point where the data is. RAM is called volatile memory; information in RAM will disappear if the power is switched off before it is saved to disk. There is also a form of non-volatile RAM, which must be continually energized by a battery to maintain its content. The most common form of RAM is built from semiconductor integrated circuits.
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| RAM cache |
Random Access Memory cache. Extremely fast memory chips that help the computer to operate faster by temporarily storing frequently-accessed or recently-accessed data. Internal cache (L1) is built into the CPU; external cache (L2) is on the motherboard. When the CPU needs data, it first checks the internal cache, which is the fastest source. If the data is not there, it checks the external cache. If the data still is not found, a search of the slower RAM must be made.
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| RAM disk |
Random Access Memory disk. A program which simulates a hard disk drive, using part of the computer's random access memory, for fast processing of data. Files can be copied into the RAM disk and edited. The RAM disk can not store files permanently; the updates must be written to the hard disk or floppy disk before the power is turned off.
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| RAM refresh |
Random Access Memory refresh. The recharging of dynamic RAM chips, which must be refreshed hundreds of times a second in order to hold their content.
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| Rambus DRAM |
Rambus Dynamic Random Access Memory. A high-bandwidth, high-speed DRAM from Rambus Inc. of Mountain View, California, used mainly for video accelerators.
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| Rambus Inc. |
The Mountain View, California, company which developed Rambus DRAM.
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