| 32-bit rendering 32 bits are used to store the color of each pixel on the screen. With 16-bit rendering, only about 65 thousand different colors can be used, but with 32-bit rendering, over 4 billion colors can be used, which results in more color shades and vibrant, crisp images. A/V PROFESSIONAL A/V is an acronym for audio/visual. A/V approved drives are normally the highest capacity, highest-performance disc drives and have been fine tuned to meet the requirements of today’s most demanding audio/visual applications. These A/V Professional drives can be custom-configured to optimize each system’s performance. A-B RollsA technique in which audio/video information is played back from two videotape machines rolled sequentially, often for the purpose of dubbing the sequential information onto a third tape, usually a composite master. AC coefficient Any discrete cosine transform coefficient for which the frequency in one or both dimensions is non- zero. Access.bus A serial communications protocol developed by Philips Semiconductors and Digital Equipment (DEC) in 1985 for connecting peripheral devices to a computer. Access.bus is designed for hassle-free installation and configuration of relatively low-speed devices, such as keyboards, monitors, and printers. Access.bus uses a bus topology, which enables it to support up to 125 devices. A competing standard, Universal Serial Bus (USB), is quickly becoming the serial standard of the future. ACCESS TIME The time program or device takes to locate a single piece of information and make it available to the computer for processing. DRAM (dynamic random access memory) chips for personal computers have access times of 50 to 150 nanoseconds (billionths of a second). Static RAM (SRAM) has access times as low as 10 nanoseconds. Ideally, the access time of memory should be fast enough to keep up with the CPU. If not, the CPU will waste a certain number of clock cycles, which makes it slower. Active video linesAll video lines not occurring in the horizontal and vertical blanking intervals. ADSL Short for asymmetric digital subscriber line, a new technology that allows more
data to be sent over existing copper telephone lines (POTS). ADSL supports data rates of
from 1.5 to 9 Mbps when receiving data (known as the downstream rate) and from 16 to 640
Kbps when sending data (known as the upstream rate). A GPAcronym for Accelerated Graphics Port, a new interface specification developed by Intel Corporation. AGP is based on PCI, but is designed especially for the throughput demands of 3-D graphics. Rather than using the PCI bus for graphics data, AGP introduces a dedicated point-to-point channel so that the graphics controller can directly access main memory. The AGP channel is 32 bits wide and runs at 66 MHz. This translates into a total bandwidth of 266 MBps, as opposed to the PCI bandwidth of 133 MBps. AGP also supports two optional faster modes, with throughputs of 533 MBps and 1.07 GBps. In addition, AGP allows 3-D textures to be stored in main memory rather than video memory. AGP has a couple important system requirements:
AGP-enabled computers and graphics accelerators hit the market in August, 1997. However, there are several different levels of AGP compliance. The following features are considered optional: - Texturing: Also called Direct Memory Execute mode, allows textures to be stored in main memory. Throughput: Various levels of throughput are offered: 1X is 266 MBps, 2X is 533 MBps; and 4X provides 1.07 GBps. Sideband Addressing: Speeds up data transfers by sending command instructions in a separate, parallel channel. Pipelining: Enables the graphics card to send several instructions together instead of sending one at a time. AGP Memory AGP memory refers to memory that is on the computer (system memory), not the graphics card. The graphics card, however, is able to directly access this memory as if it were its own, through the AGP bus. Data transfer through the AGP bus is also faster than transferring data through the PCI bus, since the AGP bus is dedicated solely to the graphics card, whereas the PCI bus is shared among other peripherals. AGP Texturing A texture that is in AGP memory, (in system memory) can be used as the source texture for a polygon. Therefore, only the pixels that are actually read need to be transferred to video memory, rather than unnecessarily loading the whole image. With non-AGP textures, the entire texture must be loaded into video memory before it can be used as a texture. If there is not enough available video memory, then some other texture in video memory must be released. This results in texture thrashing. AGP writing Images can be rendered into surfaces that are in AGP memory. The target surface does not have to be in video memory. AIT Advanced Intelligent Tape (AIT) is an advanced storage mechanism that uses the helical-scan recording method. The AIT recording format is new and is incompatible with other 8-mm tape drives. Aliasing Alpha Blending Analog Anti-Aliasing The measurement of a film or television viewing area in terms of relative height and width. The aspect ratio of most modern motion pictures varies between 3:5 to as large as 3:7, which creates a problem when a wide-format motion picture is transferred to the more square-shaped television screen, with its aspect ratio of 3:4. AT COMMAND SET Pronounced ay-tee command set, the de facto standard language for controlling modems. The AT command set was developed by Hayes and is recognized by virtually all personal computer modems. AT BUS The AT bus is the expansion bus on the IBM PC/AT and compatible computers. The bus is the collection of tracks (wires) on the PCB and electronic components that connect all device controllers and add-in cards. The controllers are the components that attach to peripheral devices. The bus, therefore, is the main highway for all data moving in and out of the computer. The AT bus, which runs at 8 megahertz and has a 16-bit data path, is the de facto standard for PCs. Because all IBM PCs (until the high-end PS/2 models) had an AT bus, it has been possible for manufacturers to produce expansion boards that will work with any PC. The AT bus is sometimes referred to as the ISA bus, which stands for Industry Standard Architecture. However, ISA also includes the XT bus, which is an 8-bit version of the AT bus. As processors have become more powerful, and applications more demanding, the AT bus has turned out to be the chief bottleneck in PCs. In response, IBM introduced the Micro Channel Architecture (MCA) in 1987. However, MCA was not accepted by the computer industry because it was not backward compatible with the AT-bus, so IBM has been forced to drop it. A more successful alternative to the AT bus is the Extended Industry Standard Architecture (EISA), a high-speed 32-bit bus architecture developed by a group of IBM's competitors. Unlike MCA, EISA is backward compatible with the AT bus, so a computer equipped with an EISA bus can accept AT or EISA expansion boards. While EISA has had limited success, its speeds are still insufficient for modern graphical applications. The most common solution to bypassing the AT-bus bottleneck is to include a local bus on the motherboard. A local bus communicates directly with the processor rather than using the standard computer bus. There were two competing standards for local buses: VESA local bus (VL-bus), promoted by the VESA standards group, and Peripheral Component Interconnect (PCI), designed and promoted by Intel the winner. |
