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A
Accumulation buffer:
An additional buffer that accumulates multiple renderings of a scene and integrates them for fancy visual effects. Accumulation buffers such as 3dfx's T-buffer are used primarily for full scene anti-aliasing since they can combine multiple snapshots of source image data to yield better overall visual quality.
AGP:
The Accelerated Graphics Port is an expansion bus developed by Intel specificity for the video card subsystem. It operates Independent of the PCI bus and normally runs at 66MHz (i.e., 1x). When you see multipliers attached to AGP, such as 2x or 4x, they refer to how much faster the bus will run—2x means 66MHz x 2, or 133MHz.
Alpha Channel:
In 32-bit color, 8 bits of data that are used as a separate layer to represent levels of translucency in an object.
Alpha-Blend:
Assigning an alpha transparency value to a pixel and blending it with the background scene to create invisible, or partially transparent, effects. The process is often used in games to depict special effects, such as explosions and weapon discharge. When applied to polygons, alpha-blending can simulate semi-transparent objects, such as water and glass.
ALU
Arithmetic and Logic Unit. The smart part of a processor chip that performs commands like adding, subtracting, multiplying and dividing. It also knows how to read logic commands like OR, AND, or NOT. Messages from the Control Unit instruct the ALU what to do and then it takes data from its close companion, the Registers, to perform the task.
Aperture Grille
The phosphor separation method used in a Trinitron CRT in place of a shadow mask. A series of thin, closely-spaced vertical wires are used to isolate pixels horizontally. The pixels are separated vertically by the nature of the scan lines used to compose the image.
ATA/100:
An enhanced version of the IDE I/O interface that supports 100MB/sec.
ATA/133:
An enhanced version of the IDE I/O interface that supports 133MB/sec.
ATA/66:
An enhanced version of the IDE I/O interface that supports 66MB/sec.
B
Bad Block
A block (usually the size of a sector) that cannot reliably hold data because of a media flaw or damaged format markings.
BIOS:
Basic input/Output System Software that contains your computer's most rudimentary instructions on how the operating system communicates with hardware. Your B1OS runs at startup, configures devices, and then boots the OS. Because the BIOS is so integral to getting your computer started, it's stored on a separate ROM chip, not your hard drive, to isolate it from crashes.
Bit depth:
Bit depth is the number of bits you have in which to describe something. Each additional bit in a binary number doubles the number of possibilities. By the time you have a 16-bit sequence, there are 65,536 possible levels. Add one more bit, and you double the possible accuracy (to 131,072 levels). When you have a 24-bit process or piece of 24-bit hardware, there are 16,777,216 available levels of audio.
Bitmap
File in which every pixel on screen is represented by a piece of data in memory, usually graphics although some audio formats are described as bitmapped as well. As opposed to a vector image, in which only a description of the image is stored.
Bubble Jet
Canon's trade name for its thermal drop on demand ink jet printer technology. The ink is heated, which produces a bubble that expands and ejects the ink out of the nozzle. As the bubble cools, the vacuum created draws fresh ink back into the nozzle.
Buffer:
A reserved portion of memory in which data is temporarily held, pending an opportunity to complete its transfer to or from a storage device or another location in memory.
Bump Mapping:
A visual trick that attempts to simulate a texture's roughness or smoothness, depending on how the texture reflects lights in 3D, this is usually accomplished by laying two textures onto a polygon—a base texture for the graphics, and a second displacement texture that is mapped on the object. This second texture determines how" rough " the surface will appear
Bus:
An electrical pathway over which the components inside a computer communicate with each other. There are many types of buses, including the PCI bus (which supports PCI slots) and the system bus (through which the microprocessor communicate with the rest of the system).
C
CAD:
Computer-aided design. The process of designing something on a computer, rather than on a paper-and-pencil drawing board. Most CAD work is done on powerful workstations, although high-end PCs are encroaching on this market.
CD-R
Abbreviation for Compact Disc Recordable. A type of write once, read many (WORM) CD format that allows you to write once to the disk. CD-Rs are composed of a polycarbonate plastic substrate, a thin reflective metal coating, and a protective outer coating. However, in a CD-R, a layer of organic polymer dye between the polycarbonate and metal layers serves as the recording medium. The composition of the dye is permanently transformed by exposure to a specific frequency of light. 74 Minute (650MB) and 80 Minute (700MB) CD-R media is available.
CD-ROM:
Acronym for Compact Disc - Read-Only Memory, pronounced "see-dee-rom." An optical storage device that uses compact disc technology to store up to either 650MB or 700MB, on a single 4.72" disk. A CD-ROM uses the constant linear velocity encoding scheme to store information in a single, spiral track, divided into many equal length segments. To read data, the CD-ROM disk drive must increase the rotation speed as the read head gets closer to the center of the disk, and decrease speed as the head moves back out.
CD-RW
Abbreviation for Compact Disc ReWritable. CD-RWs can be written to many times as opposed to CD-R Media which is write once, read many (WORM). CD-Rs and CD-RWs are composed of a polycarbonate plastic substrate, a thin reflective metal coating, and a protective outer coating. In a CD-R the composition of the dye is permanently transformed by exposure to a specific frequency of light. In a CD-RW, the dye is replaced with an alloy that can change back and forth from a crystalline form when exposed to a particular light, through a technology called optical phase change. The patterns created are less distinct than those of other CD formats, requiring a more sensitive device for playback. Only drives designated as "MultiRead" are able to read CD-RW reliably.
Chipset
A chipset is a group of microcircuits that orchestrate the flow of data to and from key components of a PC. This includes the CPU itself, the main memory, the secondary cache and any devices situated on the ISA, PCI, and AGP buses. The chipset also controls data flow to and from hard disks, and other devices connected to the IDE channels.
CISC
Pronounced 'sisk' and standing for Complex Instruction Set Computer, this relates to a microprocessor architecture that favors the richness of the instruction set (typically as many as 200 unique instructions) over the speed with which individual instructions are executed. See also RISC.
Clock Speed:
Also known as clock rate. The internal clock speed of a computer processor, normally expressed in MHz. The faster the clock speed, the faster your computer will perform a specific operation, assuming the other components in the system, such as disk drives, can keep up with the increased speed. Current clock speeds with processor types. The Pentium III is capable of 1Ghz(1000Mhz), the Pentium 4 is capable of 1.5GHz, and the Athlon is capable of 1.2GHz. Because of the different technologies incorporated into the different chips with lower clock speeds can out perform those with higher clock speeds.
CMOS
Motherboards also include a separate block of memory made from very low power consumption CMOS (complementary metal oxide silicon) RAM chips, which is kept ‘alive’ by a battery even when the PC’s power is off. This is used to store basic information about the PC’s configuration: number and type of hard and floppy drives, how much memory, what kind and so on. All this used to be entered manually, but modern auto-configuring BIOSes do much of this work, in which case the more important settings are advanced settings such as DRAM timings. The other important data kept in CMOS memory is the time and date, which is updated by a Real Time Clock (RTC). The clock, CMOS RAM and battery are usually all integrated into a single chip. The PC reads the time from the RTC when it boots up, after which the CPU keeps time - which is why system clocks are sometimes out of sync. Rebooting the PC causes the RTC to be reread, increasing their accuracy.
Coaxial Cable:
Abbreviation coax. A High Capacity cable used in networking and the Internet. It contains an inner copper conductor surrounded by plastic insulation and an outer braided copper or foil shield. Coaxial cable is used for broadband (@Home Internet Service) and baseband communications networks. Coax is also used by cable television because the cable is usually free from external interference, and permits very high transmission rates over long distances.
Coprocessor:
A microprocessor chip that assists the main microprocessor in a computer, usually by handing some specialized task such as graphics.
CPU:
Central Processing Unit. The computing and control part of the computer. The CPU in a main frame computer may be contained on many printed circuit boards; the CPU of a mini computer may be contained on several boards; and the CPU of a PC is contained in a single extremely powerful microprocessor.
CRT:
Cathode-Ray Tube. A display devise used in computer monitors and television sets. A CRT displays consists of a glass vacume tube that contains three electron guns (red, green, and blue). Electron streams from these guns sweep rapidly across the inside of the screen from the upper-left to the lower-right. The inside of the screen is covered in thousands of phosphor dots that glow when they are struck by the electron beam. To stop the image from flickering, the beams sweep at a rate of about 60 to 200 times per second, depending on the phosphor persistence and the scanning mode used-interlaced or non-interlaced. This is known as refresh rate and is measured in Hz.
D
Data Cache
The Data Cache works very closely with the 'processing partners', the ALU, Registers and the Decode Unit. This is where specially labeled data from the Decode Unit are stored for later use by the ALU and where final results are prepared for distribution to different parts of the computer.
DDR RAM
Double Data Rate: a memory technology that works by allowing the activation of output operations on the chip to occur on both the rising and falling edge of a clock cycle, thereby providing an effective doubling of the clock frequency without increasing the actual frequency.
Decode Unit
The Decode Unit does just that - it decodes or translates complex machine language instructions into a simple format understood by the Arithmetic Logic Unit (ALU) and the Registers. This makes processing more efficient.
DHCP:
Dynamic Host Control Protocol. DHCP is used to dynamically assign IP addresses to machines. Utilizing a DHCP server greatly decreases the workload of Windows NT administrators, since It automatically assigns all the TCP/IP information required by a machine. It also allows them to manage their entire collection of IP addresses in one piece. You may be familiar with the infamous Windows message that asks "Obtain an IP address from a DHCP server? "
Die
The formal term for an area of silicon containing an integrated circuit. A die has many layers, each designed for a specific function, and refers to a semiconductor component or part that has not yet been packaged. The popular term for a die is chip.
DIMM:
Dual inline Memory Module. A DIMM is a RAM module configuration that allows dual channels to be used in a single interface. On a motherboard's, that would be dual 32-bit memory paths forming a single 64-bit path. Before DIMMs, RAM modules came in SIMMs (Single Inline Memory Modules), which provided a single 32-bit path. With most SIMM motherboards, memory modules needed to be installed in pairs. DIMMs can be installed individuality. DIMMs tend to be faster and hold more memory than their SIMM counterparts.
Direct3D:
A subset of Microsoft's DirectX API. This interface allows developers to use hardware acceleration for 3D graphics, which helps games run faster by offloading the 3D processing onto a dedicated piece of hardware.
DirectX:
A collection of APIs developed by Microsoft. This driver model helps create a unified multimedia platform on PCs. Parts include Direct3D, DirectSound, Directlnput, DirectDraw, and DirectPlay. Multimedia developers can write to the standard DirectX API instead of writing to individual hardware APIs and know hardware that supports DirectX will work. It also allows graphics apps to take advantage of hardware acceleration supported by graphics accelerators.
Dithering:
When an image's colour depth is lowered from a higher count to a lower count, it is said to be dithered down. When this happens, any lost colour data may be seen by the naked eye as dotted patterns or extraneous artifacts.
DNS:
Domain Name System. This name-resolution software enables users to locate by domain name computers that are on the Internet or on a UNIX network. A DNS server holds a database of domain names and their matching IP addresses.
DP:
Dot Pitch. In a monitor, the vertical distance between the centers of like coloured phosphors on the screen of a colour monitor, measured in millimeters (mm). As the dot pitch becomes smaller, the finer detail appears on the screen; strait lines become sharper and colours more vivid. Today's monitors often have a dot pitch of between .28MM and .25MM. If the number is lower it refers to the horizontal dot pitch only and not the vertical which will be higher making the actual dot pitch either .26MM or .25MM.
DVD:
When DVD technology first appeared in households, users were simply popping DVD discs into their DVD players to watch movies - an option to the then-conventional VCR. But just as compact disc technology evolved so that users could record and erase and re-record data onto compact discs, the same is now true of DVDs. But with so many different formats -- DVD+R, DVD+RW, DVD-RAM, DVD-R, DVD-RW, DVD-ROM -- how do users know which DVD format is compatible with their existing systems, and why are there so many different formats for DVDs? The following information sheds some light on DVD's different flavors, the differences between them and the incompatibility issues that the differing technologies have sprouted.
The crucial difference among the standards is based on which manufacturers adhere to which standards. Similar to the old VHS/Beta tape wars when VCRs first hit the markets, different manufacturers support different standards.
DVD-ROM was the first DVD standard to hit the market and is a read-only format. The video or game content is burned onto the DVD once and the DVD will run on any DVD-ROM-equipped device. Capacity of a DVD disc is up to 9.4GB.
DVD+R and DVD+RW formats are supported by Philips, Sony, Hewlett-Packard, Dell, Ricoh, Yamaha and others. Capacity on these discs 4.7GB although th newer Dual layer formats are 8.5GB in size.
DVD+R is a recordable DVD format similar to CD-R. A DVD+R can only record data once and then the data becomes permanent on the disc. The disc can not be recorded onto a second time.
DVD+RW is a re-recordable format similar to CD-RW. The data on a DVD+RW disc can be erased and recorded over numerous times without damaging the medium.
DVDs created by a +R/+RW device can be read by most commercial DVD-ROM players.
DVD-R, DVD-RW and DVD-RAM formats are supported by Panasonic, Toshiba, Apple Computer, Hitachi, NEC, Pioneer, Samsung and Sharp. These formats are also supported by the DVD Forum. Capacity on these discs 4.7GB although th newer Dual layer formats are 8.5GB in size.
DVD-R is a recordable DVD format similar to CD-R and DVD+R. A DVD-R can only record data once and then the data becomes permanent on the disc. The disc can not be recorded onto a second time. There also are two additional standards for DVD-R disks: DVD-RG for general use, and DVD-RA for authoring, which is used for mastering DVD video or data and is not typically available to the general public.
DVD-RW is a re-recordable format similar to CD-RW or DVD+RW. The data on a DVD-RW disc can be erased and recorded over numerous times without damaging the medium.
DVDs created by a -R/-RW device can be read by most commercial DVD-ROM players.
DVD-RAM discs can be recorded and erased repeatedly but are only compatible with devices manufactured by the companies that support the DVD-RAM format. DVD-RAM discs are typically housed in cartridges.
E
EAX:
Environmental Audio. Creative Labs proprietary 3D sound algorithm based on reverb.
EDO:
Extended Data Out Random Access Memory. Low-cost memory that loses data if it's not recharged regularity (known as refreshing).
Environment Mapping:
A texture effect that applies a reflection of the surrounding game environment on the texture itself. This is useful for giving highly reflective appearance, such as simulating chrome.
Ethernet
Ethernet was developed in the mid 1970's by the Xerox Corporation, and in 1979 Digital Equipment Corporation (DEC) and Intel joined forces with Xerox to standardize the system. The first specification by the three companies called the 'Ethernet Blue Book' was released in 1980, it was also known as the 'DIX standard' after the collaborators' initials. It was a 10 Mbit/s system that used a large coaxial cable backbone cable running throughout a building, with smaller coaxial cables tapped off at 2.5m intervals to connect to workstations. The large coaxial cable - usually yellow in colour - became known as 'Thick Ethernet' or 10Base5. The key to this nomenclature is as follows: the '10' refers to the speed (10 Mbit/s), the 'Base' refers to the fact that it is a baseband system and the '5' is short for the system's maximum cable length run of 500m.
Performance limitations have been overcome by newer versions, 100BaseT - also known as Fast Ethernet - supporting data transfer rates of 100 Mbit/s and Gigabit Ethernet data rates of 1 Gbit/s. With switched Ethernet, each sender and receiver pair have the full bandwidth. implementation is usually in either an interface card or in circuitry on a primary circuit board. Ethernet cabling conventions specify the use of a transceiver to attach a cable to the physical network medium. The transceiver performs many of the physical-layer functions, including collision detection. The transceiver cable connects end stations to a transceiver.
F
FAT file system
A file system based on a file allocation table, maintained by the operating system, to keep track of the status of various segments of disk space used for file storage. The 32-bit implementation in Windows 95/98 is called Virtual File Allocation Table (VFAT).
Firewall:
A software system that isolates a network (such as an internal corporate intranet) from the rest of the Internet, permitting only specific data to pass in and out.
FireWire
Formally known as IEEE-1394. See IEEE-1394
Floating Point:
A fractional number, such as 9.95 or 9.86. Computers have a more difficult time working with FP numbers than they do with integers (whole numbers), but the higher precision of FP is required for some operations
Fogging:
The ability for a video card to correctly simulate fog in an environment, and to render objects that enter that fog correctly. This creates a simulation of distance and atmosphere--the farther the object or terrain is, the higher likelihood it will be enveloped in fog.
FPU
Floating Point Unit. A formal term for the math co-processors (also called numeric data processors, or NDPS) found in many personal computers. FPUs perform certain calculations faster than CPUs because they specialize in floating-point math, whereas CPUs are geared for integer math. Today, most FPUs are integrated with the CPU rather than packaged and sold separately.
FSB
Frontside bus. The bus within a microprocessor that connects the CPU with main memory. The so-called dual independent bus (DIB) architecture allows a processor to use both this and the backside bus (which connects the CPU and the Level 2 cache) simultaneously.
G
GDDR:
A category of DDR SDRAM chips that are made to specifically handle the enormous demands of graphics processing. Currently, three standards exist: GDDR-I, GDDR-II and GDDR-III, and almost all modern graphics cards use this type of memory. The standards differ in their clock speed, bandwidth, and power-management capabilities. GDDR is typically more expensive than DDR memory.
Gigabyte:
Abbreviated GB. One GB = 1000 megabytes. Giga bytes are commonly used to represent hard disk capacity.
Gouraud-Shading:
A method for making 3D objects in computer graphics appear naturally lighted. The computer calculates a lighting effect for each polygon vertex and interpolates the result across the entire face of the polygon.
GUI
Graphical User Interface. A graphics-based user interface that incorporates icons, pull-down menus and a mouse. The GUI has become the standard way for users to interact with a computer. The first graphical user interface was designed by Xerox Corporation’s Palo Alto Research Centre in the 1970s, but it was not until the 1980s and the emergence of the Apple Macintosh that graphical user interfaces became popular. The three major GUIs in popular use today are Windows, Macintosh and Linux.
H
Hubs/Repeaters
Hubs/repeaters are used to connect together two or more network segments of any media type. In larger designs, signal quality begins to deteriorate as segments exceed their maximum length. Hubs provide the signal amplification required to allow a segment to be extended a greater distance. Passive hubs simply forward any data packets they receive over one port from one workstation to all their remaining ports. Active hubs, also sometimes referred to as 'multiport repeaters', regenerate the data bits in order to maintain a strong signal.
Hubs are also used in star topologies such as 10BaseT. A multi-port twisted pair hub allows several point-to-point segments to be joined into one network. One end of the point-to-point link is attached to the hub and the other is attached to the computer. If the hub is attached to a backbone, then all computers at the end of the twisted pair segments can communicate with all the hosts on the backbone.
An important fact to note about hubs is that they only allow users to share Ethernet. A network of hubs/repeaters is termed a 'shared Ethernet', meaning that all members of the network are contending for transmission of data onto a single network (collision domain). This means that individual members of a shared network will only get a percentage of the available network bandwidth.
While repeaters allow LANs to extend beyond normal distance limitations, they still limit the number of nodes that can be supported. Bridges, routers and switches, however, allow LANs to grow significantly larger by virtue of their ability to support full Ethernet segments on each port.
I
IDE:
Integrated Drive Electronics. A popular hard-disk interface standard, and has medium to fast data transfer rates. IDE gets its name from the fact that the electronic control circuitry needed is actually located on the drive itself, thus eliminating the need for a separate hard-disk controller.
IEEE-1394:
Also widely referred to as FireWire, IEEE 1394 was approved by the Institute of Electrical and Electronics Engineers (IEEE) in 1995. Originally conceived by Apple, who currently receives $1 royalty per port, several leading IT companies - including Microsoft, Philips, National Semiconductor and Texas Instruments - have since joined the 1394 Trade Association. IEEE 1394 is similar to USB in many ways, but much faster. Both are hot-swappable serial interfaces, but IEEE 1394 provides high-bandwidth, high-speed data transfers significantly in excess of what USB offers. There are two levels of interface in IEEE 1394, one for the backplane bus within the computer and another for the point-to-point interface between device and computer on the serial cable. A simple bridge connects the two environments. The backplane bus supports data-transfer speeds of 12.5, 25, or 50 Mbit/s, the cable interface speeds of 100, 200 and 400 Mbit/s - roughly four times as fast as a 100BaseT Ethernet connection and far faster than USB's 1.5 Mbit/s or 12 Mbit/s speeds. A 1394b specification aims to adopt a different coding and data-transfer scheme that will scale to 800 Mbit/s, 1.6 Gbit/s and beyond. Its high-speed capability makes IEEE 1394 viable for connecting digital cameras, camcorders, printers, TVs, network cards and mass storage devices to a PC.
Instruction Cache
The Instruction Cache is a warehouse of instructions right on the chip, so that the microprocessor doesn't have to stop and look in the computer's main memory for instructions. This quick access makes processing fast as instructions are 'fetched' to the Prefetch Unit where they are put in the proper order for processing.
Interrupt
An asynchronous operating condition that disrupts normal execution and transfers control to an interrupt handler. Interrupts are usually initiated by I/O devices requiring service from the processor.
ISA:
Industry Standard Architecture. The 16-bit bus design was first used in IBM's PC/AT Computer in 1984. ISA has a bus speed of 8 MHz, and a maximum throughput of 8 megabytes per second. EISA is a 32-bit extension to this standard bus.
Itanium
Brand name for the first product in Intel's IA-64 family of processors, formerly codenamed Merced.
J
JPEG
Joint Photographic Experts Group: supported by the ISO, the JPEG committee proposes an international standard primarily directed at continuous-tone, still-image compression. Uses DCT (Discrete Cosine Transfer) algorithm to shrink the amount of data necessary to represent digital images anywhere from 2:1 to 30:1, depending on image type. JPEG compression works by filtering out an image's high-frequency information to reduce the volume of data and then compressing the resulting data with a compression algorithm. Low-frequency information does more to define the characteristics of an image, so losing some high frequency information doesn't necessarily affect the image quality.
K
Kbps:
Kilobits Per Second. The number of bits, or binary digits, transmitted every second, measured in multiples of 1024 bits per second. Used as an indicator of communications transmission rate.
Kernel
The portion of "Operating System" that manages computer resources including the processor.
Kilobyte:
Abbreviated K, KB, or Kbyte. 1024 bytes
L
LAN/WAN
Last Updated - 10May01 The first networks were time-sharing networks that used mainframes and attached terminals. Such environments were implemented by both IBM's System Network Architecture (SNA) and Digital's network architecture. Local area networks (LANs) evolved around the PC revolution and provide high-speed, fault-tolerant data networks that cover a relatively small geographic area or that is confined to a single building or group of buildings. They provide connected users with shared access to devices and applications and allow them to exchange files and communicate via electronic mail. Wide area networks (WANs) cover broader geographic areas, often using transmission facilities provided by common carriers, such as telephone companies, to interconnect a number of LANs.
Whilst LANs and WANs make up the majority of networks - indeed, the Internet can be correctly regarded as the largest WAN in existence - there are many different types of network, categorized by a number of distinguishing characteristics:
LCD:
Liquid Crystal Display. Commonly used in portable computers because of the thin design and lack of a tube. Electrical current is used to align crystals in a special liquid. The rod-shaped crystals are contained between two parallel transparent electrodes, and when current is applied, they change their orientation, creating a darker area. Many LCD screens are also back-lit or side-lit to increase visibility and reduce the possibility of eyestrain.
Legacy
Hardware and device cards that don’t conform to the Plug and Play standard.
M
Megabyte:
Abbreviated MB. One MB = 1,048,576 bytes. Megabytes are a common way to represent memory or hard disk space.
Memory:
The primary random-access memory (RAM) installed in the computer. The operating system copies application programs from disk into memory, where all program execution and data processing takes place; results are written back out to disk again. The amount of memory installed in the computer can determine the size and number of programs that can run, as well as the size of the largest data file.
MHz:
Megahertz. One million Cycles per second. A processor's clock speed is often expressed in MHz. The original IBM PC operated an 8088 running at 4.77 MHz, the current speed king is the Intel Pentium 4 running at 1.5GHz or 1500MHz. Also see "clock speed" for more info.
Microprocessor:
A CPU on a single chip. The first microprocessor was developed by Intel in 1969. The microprocessors most commonly used in PCs are the Pentium III and 4, the Celeron, the Athlon and Duron, and the Power Mac G3 and G4.
Modem
MOdulator/DEModulator: a modem transforms (modulates) digital information into an analogue signal that can be sent across a telephone line. It also demodulates an analogue signal it receives from the telephone line, converting the information contained in the signal back into digital information.
Monitor:
A video output device capable of displaying text and graphics. The to most common types of monitors are the CRT(Cathode-Ray Tube) and LCD(Liquid Crystal Display)
Multitexturing:
The process of applying multiple textures to polygons in a model. This is usually done by performing multiple texturing passes (called blending) until the image is completed.
N
Napster
Created in 1999, Napster is a controversial music indexing service that gives individuals access to one another's MP3 files by creating a unique file-sharing system via the Internet.
NetBEUI:
NetBIOS Extended User Interface. A networking protocol used by Windows For Workgroups and Windows NT.
Network Address Translation or NAT:
NAT enables a network of computers to present itself to the Internet using just one IP address. NAT converts the address of each machine on the network into the one IP address that's used on the Internet, then converts information from the Internet and sends it back to the proper computer on the LAN. NAT also acts as a security firewall by hiding the IP addresses of each computer on the network.
NIC
Network Interface Card. Commonly referred to as NICs, are used to connect a PC to a network. The NIC provides a physical connection between the networking medium and the computer's internal bus, and is responsible for facilitating an "access method" to the network (OSI Layers 1 and 2). Most NICs are designed for a particular type of network, protocol, and media, although some can serve multiple networks. Cards are available to support almost all networking standards, including the latest Fast Ethernet environment. Fast Ethernet NICs are often 10/100 capable, and will automatically set to the appropriate speed. Full-duplex networking is another option, where a dedicated connection to a switch allows a NIC to operate at twice the speed.
Nodes:
Any computer connected to a network is referred to as a node.
O
Open GL
Open Graphics Library: a standardized 2- and 3D graphics library that has its historical roots in the Silicon Graphics IrisGL library. It has become a de facto standard endorsed by many vendors and can be implemented as an extension to an operating system or a window system and is supported by most UNIX-based workstations, Windows and X Windows. Some implementations operate entirely in software, while others take advantage of specialized graphics hardware.
P
P5
The Intel codename for the original 60/66MHz Pentiums introduced in 1993. Subsequent faster clock-speed chips were referred to as P54 and the MMX version as P55.
P6
The Intel codename for the Pentium Pro, which is optimized for 32-bit applications. The P6 generation includes the Pentium Pro, Pentium II and Pentium III.
PCI:
Peripheral Component Interconnector. A specification Introduced by Intel that defines a local bus that allows up to ten PCI-compliant expansion cards to be plugged into the computer. One of these must be the PCI controller card(usually on the motherboard), but the others can include video cards, network cards, SCSI cards, or any other basic input/output function.
PCIe (PCI Express):
An I/O interconnect bus standard (which includes a protocol and a layered architecture) that expands on and doubles the data transfer rates of original PCI. PCI Express is a two-way, serial connection that carries data in packets along two pairs of point-to-point data lanes, compared to the single parallel data bus of traditional PCI that routes data at a set rate. Initial bit rates for PCI Express reach 2.5Gb/s per lane direction, which equate to data transfer rates of approximately 200MB/s. PCI Express was developed so that high-speed interconnects such as 1394b, USB 2.0, InfiniBand and Gigabit Ethernet would have an I/O architecture suitable for their transfer high speeds. At present, PCI Express is most used in the graphics card market where the 16x(16 Lane) PCIe slot is replacing the AGP slot (Accelerated Graphics Port).
PCIe SLI
The SLI acronym now stands for "Scalable Link Interface" instead of scan line interleave when it was a term for Voodoo2 PCI video cards. Supporting motherboards will have 2 PCI Express 16x slots to accomidate a pair of SLI supporting video cards. Cards working on an SLI system can almost double performance as each video card only needs to handle half the work load.
PCMCIA:
PC Memory Card International Association. Also known as PC cards, uses a 68-pin connector, with longer power and ground pins, so they are always engage before the signal pins. There are several versions that have been approved. Most PCMCIA devices are: Modems, Ethernet, dynamic RAM, and Flash memory cards.
Processing Pipeline:
The path through which data passes in a CPU or graphics processor. The larger the bandwidth (i.e., 128-bit versus 64-bit) the more data the processor can handle.
Protocol:
A formally defined way to perform an action Diplomatic protocols specify how to greet foreign dignitaries; computer protocols specify interactions between computing devices and programs. For example, HTTP (hypertext transfer protocol) defines how web servers and browsers should exchange data over the Internet.
R
RAID
Redundant Array of Independent Disks. A disk subsystem (that appears as a single large, fast, super-reliable disk drive) composed of more than one (usually equal-sized) disk drives (called an array) to provide improved reliability, response time, and/or storage capacity.
Several techniques are used:
Spanning or Software Striping: splits the data from a single file or database onto several disk drives--this permits many simultaneous (up to as many disk drives as are used) accesses to the data
Mirroring: duplicates the data from one disk onto others so that the data are still available if a drive fails.
Duplexing: duplicates both the disks and the disk controllers (the printed circuit board that goes between the PC's bus and the disk drive)
All of these techniques speed response times during periods of heavy loading, since more than one physical disk drive is supplying data simultaneously.
RAID arrays may also support the following:
Hot Swapping: a failed disk drive can be removed and replaced, and the data can be automatically restored to the new disk while the subsystem is powered up and continues to operate in production service
Hot Sparing: an extra disk drive in the array is automatically put into service (no need to manually plug in a new one) when a failure occurs
Spindle Synchronization: synchronizes the rotation of all drives in an array, making it easier for the controller to track which disk sectors can be read soonest
Five RAID levels are defined (six if you count what some people call Level 0) and described in the table below.
RAID Level Functionality Comments
0 Data are striped across available disks (to improve access times), with no redundancy.
Not part of the original RAID definition. Not RAID, since there is no redundancy.
1 Two disk drives are mirrored (both store the same data), using a single disk controller. Data can be read off both drives simultaneously (either drive can service any request), providing improved performance.
Often implemented in software. Doubles the number of disk drives required, therefore suited only to smaller storage requirements. Provides faster write times than RAID 4 or 5.
2 Data are spanned across multiple disks, and additional disks are used to store Hamming codes (to detect and correct errors or recover from failed drives). Four data disks would require three additional error detection and correction disks.
Offers the greatest redundancy but is not currently commercially available because of the high cost.
3 Data are striped byte by byte across two or more (four is apparently best) data disks (first byte to first disk, second byte to next disk, and so on--written in parallel to all disks). A parity byte is constructed from the corresponding bytes on the data disks and is written to one additional disk, which is dedicated as a parity disk. The contents of a failed disk can be reconstructed from the other disks.
Considered best for larger transfers, such as graphics or imaging files.
4 Same as RAID 3, but data are striped (and parity is constructed) in disk sectors rather than bytes.
Has lower performance than RAID 5; is seldom used or available.
5 Data are striped sector by sector across two or more disks. Parity information sectors are striped along with the data on each disk, and there is no dedicated parity disk.
Considered best for smaller transfers. Offers better write (and the same read) performance as RAID 4.
RDRAM:
Rambus Dynamic Random Access Memory. A fading memory standard in the retail world due legal issues with Intel, RDRAM is still the fastest memory available but is also the most expensive. RDRAM runs at 800Mhz compared to current standards of DDR RAM, which runs at 266/333/400MHz or DDR2 RAM which runs at 400/533 and most recently 667Mhz. RDRAM must be installed in pairs and dummy chips are placed in un-used slots on the motherboard.
Registers
The Registers are a mini-storage area for data used by the Arithmetic Logic Unit (ALU) to complete the tasks the Control Unit has requested. The data can come from the data cache, main memory or the control unit and are all stored at special locations within the Registers. This makes retrieval for the ALU quick and efficient.
Registry
The database repository for information about a computers configuration. The Registry supercedes use of separate INI files for all system components and applications that know how to store values.
Resolution:
The Degree of sharpness of a printed or displayed image, often expressed in dpi(dots/pixels per inch). Resolution depends on the number of elements that make up the image, either dots on a printer or pixels on a monitor. The higher the number per inch, the higher the resolution of the image appears.
RISC
Reduced Instruction Set Computer. A microprocessor architecture that recognizes a relatively limited number of instructions, favoring the speed at which individual instructions execute over the richness of the instruction set. See also CISC.
RJ45:
RJ being short for Registered Jack, RJ 45 is an eight pin connector used for data transmission over twisted- pair wires. The similar RJ11 is a four or six pin connector used for voice transmission like your telephone
Routers
Routing achieved commercial popularity in the mid-1980s - at a time when large-scale internetworking began to replace the fairly simple, homogeneous environments that had been the norm hitherto. Routing is the act of moving information across an internet work from a source to a destination. It is often contrasted with bridging, which performs a similar function. The primary difference between the two is that bridging occurs at Layer 2 (the link layer) of the OSI reference model, whereas routing occurs at Layer 3 (the network layer). This distinction provides routing and bridging with different information to use in the process of moving information from source to destination, so the two functions accomplish their tasks in different ways.
Routers use information within each packet to route it from one LAN to another, and communicate with each other and share information that allows them to determine the best route through a complex network of many LANs. To do this, routers build and maintain 'routing tables', which contain various items of route information - depending on the particular routing algorithm used. For example, destination/next hop associations tell a router that a particular destination can be gained optimally by sending the packet to a particular router representing the "next hop" on the way to the final destination. When a router receives an incoming packet, it checks the destination address and attempts to associate this address with a next hop.
S
64-bit Processor
A 64-bit processor is a microprocessor with a word size of 64 bits, a requirement for memory and data intensive applications such as computer-aided design (CAD) applications, database management systems, technical and scientific applications, and high-performance servers. 64-bit computer architecture provides higher performance than 32-bit architecture by handling twice as many bits of information in the same clock cycle. The 64-bit processor is backwards compatible with older applications and operating systems; it detects whether an application or operating system is 16-bit, 32-bit, or 64-bit and computes accordingly. This is essential for enterprise situations where purchasing new software is not feasible. The Athlon64 is a 64-Bit processor markted by AMD. Intel will in the future have a 64-Bit processor available called the EM64T.
S/PDIF:
Sony/Philips Digital Interface. A standard interface for sending digital audio data. Soundcards with S/PDIF jacks let you use your computer as a mini recording studio.
SATA
The current standard is Serial ATA 1.0, which was released in August 2001. It specifies communications between the host and the Serial ATA drive. It also defines a maximum transfer rate of 1.5 gigabits per second (Gb/sec) or 150 MB/sec, a modest increase over the current parallel ATA top transfer rate of 133 MB/sec. Current hard drives on the market conform to the 1.0 standard.
SCSI:
Small computer standard interface. This is a multidevice, chained interface used in many devices such as hard disk drives and CD-ROM drives.
Sectors/Tracks
When a disk undergoes a low-level format, it is divided it into tracks and sectors. The tracks are concentric circles around the central spindle on either side of each platter. Tracks physically above each other on the platters are grouped together into cylinders which are then further subdivided into sectors of 512 bytes apiece. The concept of cylinders is important, since cross-platter information in the same cylinder can be accessed without having to move the heads. The sector is a disk's smallest accessible unit. Drives use a technique called zoned-bit recording in which tracks on the outside of the disk contain more sectors than those on the inside.
Allocating and tracking individual data sectors on a large drive would require a huge amount of overhead, causing file handling efficiency to plummet. To improve performance, data sectors are allocated in groups called clusters.
Semiconductor
A solid-state substance with conductive properties that can be altered with electricity. Silicon performs as a semiconductor when chemically combined with other elements. A semiconductor is also halfway between a conductor and an insulator. When charged with electricity or light, semiconductors change their state from non-conductive to conductive or vice versa. The most significant product built from a semiconductor is the transistor.
Silicon Ingot
A large, cylindrical, single crystal made from purified silicon. The cylinder is sliced into thin wafers which are used for making computer chips.
Silicon Wafer
Intel uses wafers of pure silicon cut from a silicon ingot to make microprocessors. Silicon, the primary ingredient of beach sand, is a semiconductor of electricity. Semiconductors are materials that can be altered to be either a conductor or an insulator.
SIMM:
Single Inline Memory Module. A RAM module that provides a single 32-bit path. See DIMM.
Sledgehammer
Codename for AMD's x86-64 design for extending the iA-32 architecture to support 64-bit code and memory addressing.
SLI:
Scan Line Interleave. A term used when two video cards work in tandem, with one video card rendering the odd lines of a video output while the other card renders the even lines It dramatically increases speed but at the cost of more hardware. With the 3dfx Voodoo2, the slave 3D card will send its rendered output via a ribbon cable into the master video card, where the combined output is then generated on screen by the master card. Having two video cards work as one raises overall rendering performance, and in the Voodoo2's case, allows a higher rendering resolution to be obtained.
Also See: PCIe SLI
Slot 1
The form factor for Intel's Pentium II CPUs. Slot 1 replaces the Socket 7 and Socket 8 form factors used by previous Pentium processors. It is a 242-contact daughtercard slot that accepts a microprocessor packaged as a Single Edge Contact (SEC) cartridge. Communication between the Level 2 cache and CPU is at half the CPU's clock speed.
Slot 2
An enhanced Slot 1, which uses a somewhat wider 330-contact connector SEC cartridge that holds up to four processors. The biggest difference from Slot 1 is that the Level 2 runs at full processor speed. Intel's Xeon chips were the first to use Slot 2.
Slot A
A receptacle on the motherboard for a K7/Athlon CPU chip from AMD. It is physically similar to Slot 1, but has different electrical requirements.
Socket 370
A CPU plug and socket from Intel for Pentium CPUs that is more economical than the elaborate Slot 1 system introduced with the Pentium II. Socket 370 accepts a 370-pin PPGA (plastic pin grid array) chip package, instead of the SEC (single edge cartridge) Slot 1 package. Socket 370 chips and motherboards cost less to manufacture.
Socket 423
A recepticle on the motherboard designed to support the original Intel Pentium 4 CPUs. Socket 423 Pentium 4 CPUs operate on a 400Mhz FSB (Quad pumped 100Mhz Bus) and made used of RDRAM instead of SDRAM. The number 423 refers to the number interface pins on the CPU.
Socket 478
A recepticle on the motherboard designed to support the second generation Intel Pentium 4 CPUs. Origianlly designed with a FSB was clocked at 533Mhz (Celeron CPUs continue to run at this speed) but is now clocked up to 800Mhz and supports DDR 266/333/400Mhz memory. The number 478 refers to the number interface pins on the CPU.
Socket 7
The receptacle on the motherboard that holds a Pentium CPU chip. It is also used to hold Pentium chip clones such as the 5x86, 6x86, K5, K6, K6-2, and K6-III.
Socket 754
A recepticle on the motherboard designed for the origional AMD Athlon64 and the buget level Sempron CPUs. The number 754 refers to the number interface pins on the CPU.
Socket 775
A recepticle on the motherboard designed to support the newest generations of the Intel Pentium 4 CPUs. The FSB contimues to run at 800Mhz on this design but can support PCIe and newer DDR2 400/533/667Mhz Memory if the motherboard is properly equiped. The number 775 refers to the number interface pins on the CPU.
Socket 8
The receptacle on the motherboard that holds a Pentium Pro CPU chip.
Socket 939
A recepticle on the motherboard designed for the newest AMD Athlon64 and Athlon64-FX CPUs. The number 939 refers to the number of interface pins on the CPU.
Socket 940
A recepticle on the motherboard designed to support the AMD Opteron CPUs, which are desined for workstation and server environment. These setups can support up to 8 individual CPUs if the motherboard is equiped with the appropriate number of Socket 940 sockets.The number 940 refers to the number interface pins on the CPU.
Socket A
A CPU plug and socket from AMD for the Thunderbird and Duron CPUs. It is also known as Socket 462 because it has a 462 pin interface. Socket A supports a 200/266/333/400MHz FSB. The newest Socket A motherboards support the Athlon XP and Sempron CPUs
Sound Card
Also called sound board and audio adapter, this is an expansion board that records and plays back sound, providing outputs directly to speakers or an external amplifier. The de facto standard for sound card compatibility in PCs is Creative Labs' Sound Blaster.
Spooler:
A scheduler for the printing process. It coordinates activity among other components of the print model and schedules all print jobs arriving at the print server.
SSE:
Streaming SIMD Extensions. A set of 70 instructions from Intel that speed up the Pentium Ill's floating-point, integer, and memory streaming power. SIMD stands for Single Instruction Multiple Data. This processing strategy tells a single programming instruction to perform the same operation on two or more pieces of data. SSE is similar to AMD's 3Dnow! but brings more to the table via memory streaming enhancement. As is the case with 3DNow!, games and applications must be optimized for SSE to take advantage of the performance boosts.
Static IP addresses:
IP addresses that are permanently assigned to either a client machine or the server of a TCP/IP network—though a static IP address is usually assigned to the server.
Switches
LAN switches are an expansion of the concept in LAN bridging. They operate at Layer 2 (link layer) of the OSI reference model, which controls data flow, handles transmission errors, provides physical (as opposed to logical) addressing, and manages access to the physical medium. Switches provide these functions by using various link-layer protocols - such as Ethernet, Token Ring, and FDDI - that dictate specific flow control, error handling, addressing, and media-access algorithms.
LAN switches can link four, six, ten or more networks together, and have two basic architectures: cut-through and store-and-forward. In the past, cut-through switches were faster because they examined the packet destination address only before forwarding it on to its destination segment. A store-and-forward switch, on the other hand, accepts and analyses the entire packet before forwarding it to its destination.
It takes more time to examine the entire packet, but it allows the switch to catch certain packet errors and keep them from propagating through the network. By the late 1990s, the speed of store-and-forward switches had caught up with cut-through switches so the difference between the two was minimal. By then, a large number of hybrid switches had become available that mixed both cut-through and store-and-forward architectures.
T
3D API
A 3D Application Programming Interface controls all aspects of the 3D rendering process. A mass of conflicting standards exist, including Microsoft’s DirectX and OpenGL, Intel’s 3DR, Reality Lab and Brender. Most are custom designed for either entertainment or serious 3D animation.
Texels:
Short for TEXture ELement. Refers to the individual pixel that makes up a bitmapped graphic that is used as a texture when it's applied on a polygon.
Texture Mapping:
The process of applying textures to 3D objects in computer graphics.
Textures:
The surface graphics on a 3D object. Without textures, 3D objects look like naked skeletons of polygons. Textures add realism --a brick wall, the skin of a lizard, or the gleaming metal surface of a spaceship. A 3D program stores a texture as a graphics pattern and applies it to the structure of polygons.
Trinitron
See Aperture Grille
Trojan Horse
A program that appears legitimate, but performs some illicit activity when it is run. It may be used to locate password information or make the system more vulnerable to future entry or simply destroy programs or data on the hard disk. A Trojan horse is similar to a virus, except that it does not replicate itself. It stays in the computer doing its damage or allowing somebody from a remote site to take control of the computer. Trojans often sneak in attached to a free game or other utility.
U
Ultra DMA:
Ultra Direct Memory Access. The fastest IDE protocol for connecting hard drives and removable storage devices Capable of 33Mbps, 66Mbps, and 100Mbps throughput.
USB:
Universal Serial Bus. Fast, digital I/0 port proposed by Intel for motherboards. Taking up far fewer resources, this port can act as a serial, parallel, mouse, keyboard, joystick, and even speaker interface. Unlike other communication ports on a PC, USB can be daisy-chained up to 127 devices.
V
V.90:
A 56K modem designed for connections that are digital at one end and only have one digital-to-analog conversion.
Video Card
An expansion card that interprets drawing instructions sent by the CPU, processes them via a dedicated graphics processor and writes the resulting frame data to the frame buffer. Also called video adapter (the term 'graphics accelerator' is no longer in use).
Video Memory:
Temporary memory that a processor or coprocessor uses to display graphics on the screen Usually this memory consists of several chips on the graphics card. It's not counted as part of a PC's main memory (RAM).
Virus
A program or piece of code that is loaded onto your computer without your knowledge and runs against your wishes. Most viruses can also replicate themselves. All computer viruses are manmade. A simple virus that can make a copy of itself over and over again is relatively easy to produce. Even such a simple virus is dangerous because it will quickly use all available memory and bring the system to a halt. An even more dangerous type of virus is one capable of transmitting itself across networks and bypassing security systems.
Since 1987, when a virus infected ARPANET, a large network used by the Defense Department and many universities, many antivirus programs have become available. These programs periodically check your computer system for the best-known types of viruses.
Some people distinguish between general viruses and worms. A worm is a special type of virus that can replicate itself and use memory, but cannot attach itself to other programs.
W
Workgroup:
A collection of computers that are grouped for viewing purposes. Each workgroup is identified by a name.
Z
Z-buffered:
In a 3D video card, local video memory is often used to form a frame buffer, which stores all sorts of data required by a 3D card in order to properly render a scene onto your monitor. With the advent of texture-mapped polygons interacting in a 3D world in realtime, the need to have a buffer with which to track positioning became a necessity. A z-buffer stores the z-axis value (front to back) of a pixel on-screen--this value is compared with incoming z-value data to determine whether the pixel will be drawn or not, and how overlapping pixels will be presented. How accurate a z-buffer is dependent on how the 3D accelerator handles z-buffer calculations, and how much memory is allocated to it. Higher color-depth rendering requires more z-buffer memory, as the amount of pixel information is made larger with more color usage. It speeds up 3D gaming by not rendering the parts of a scene that are Obscured by other objects.
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