A+ Terms, Chp. 1
Terms
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- active matrix display
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A type of flat-panel display in which the screen is refreshed more frequently than in conventional passive-matrix displays. The most common type of active-matrix display is based on a technology known as TFT (thin film transistor). The two terms, active matrix and TFT, are often used interchangeably.
ASIC Pronounced ay-sik, and short for Application-Specific Integrated Circuit, a chip designed for a particular application (as opposed to the integrated circuits that control functions such as RAM in a PC). ASICs are built by connecting existing circuit building blocks in new ways. Since the building blocks already exist in a library, it is much easier to produce a new ASIC than to design a new chip from scratch. - AT bus
- The expansion bus on the IBM PC/AT and compatible computers. The bus is the collection of wires 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.
- expansion bus
- A collection of wires and protocols that allows the expansion of a computer by inserting printed circuit boards (expansion boards). Traditionally, PCs have utilized an expansion bus called the ISA bus. In recent years, however, the ISA bus has become a bottleneck, so nearly all new PCs have a PCI bus for performance as well as an ISA bus for backward compatibility.
- ATX
- The modern-day shape and layout of PC motherboards. It improves on the previous standard, the Baby AT form factor, by rotating the orientation of the board 90 degrees. This allows for a more efficient design, with disk drive cable connectors nearer to the drive bays and the CPU closer to the power supply and cooling fan.
- cache
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Pronounced cash, a special high-speed storage mechanism. It can be either a reserved section of main memory or an independent high-speed storage device. Two types of caching are commonly used in personal computers: memory caching and disk caching.
memory cache A memory cache, sometimes called a cache store or RAM cache, is a portion of memory made of high-speed static RAM (SRAM) instead of the slower and cheaper dynamic RAM (DRAM) used for main memory. Memory caching is effective because most programs access the same data or instructions over and over. By keeping as much of this information as possible in SRAM, the computer avoids accessing the slower DRAM. - chipset
- A number of integrated circuits designed to perform one or more related functions. For example, one chipset may provide the basic functions of a modem while another provides the CPU functions for a computer. Newer chipsets generally include functions provided by two or more older chipsets. In some cases, older chipsets that required two or more physical chips can be replaced with a chipset on one chip.
- CSTN
- Short for color super-twist nematic, an LCD technology developed by Sharp Electronics Corporation. Unlike TFT, CSTN is based on a passive matrix, which is less expensive to produce. The original CSTN displays developed in the early 90's suffered from slow response times and ghosting. Recent advances in the technology, however, have made CSTN a viable alternative to active-matrix displays. New CSTN displays offer 100ms response times, a 140 degree viewing angle, and high-quality color rivaling TFT displays - all at about half the cost.
- DSTN
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Short for double-layer supertwist nematic, a passive-matrix LCD technology that uses two display layers to counteract the color shifting that occurs with conventional supertwist displays.
local bus A data bus that connects directly, or almost directly, to the microprocessor. Although local buses can support only a few devices, they provide very fast throughput. Modern PCs include both a PCI local bus and a more general ISA expansion bus for devices that do not require such fast data throughput. - PCI
- Short for Peripheral Component Interconnect, a local bus standard developed by Intel Corporation. Most modern PCs include a PCI bus in addition to a more general ISA expansion bus. PCI is also used on newer versions of the Macintosh computer.
- IDE interface
- Abbreviation of either Intelligent Drive Electronics or Integrated Drive Electronics, depending on who you ask. An IDE interface is an interface for mass storage devices, in which the controller is integrated into the disk or CD-ROM drive.
- kernel
- The central module of an operating system. It is the part of the operating system that loads first, and it remains in main memory. Because it stays in memory, it is important for the kernel to be as small as possible while still providing all the essential services required by other parts of the operating system and applications. Typically, the kernel is responsible for memory management, process and task management, and disk management.
- MBR
- Short for Master Boot Record, a small program that is executed when a computer boots up. Typically, the MBR resides on the first sector of the hard disk. The program begins the boot process by looking up the partition table to determine which partition to use for booting. It then transfers program control to the boot sector of that partition, which continues the boot process. In DOS and Windows systems, you can create the MBR with the FDISK /MBR command.
- shadow mask
- A perforated metal sheet inside a color monitor. Most color monitor screens use cathode-ray tube (CRT) technology in which electrons are fired from an electron gun onto a phosphor coating on the screen's faceplate. The phosphor converts the kinetic energy of the electrons into light and is illuminated in tiny red, green and blue dots, which comprise the image that one sees when looking at a monitor's screen. The phosphors in a group are packed so closely together that the human eye can only perceive them as a single colored pixel. Before the electron beam reaches the phosphor dots it passes through the shadow mask, a perforated metal sheet that ensures that the electron beam hits only the correctly colored phosphor dots and does not illuminate more than one dot.
- half-duplex
- Refers to the transmission of data in just one direction at a time. For example, a walkie-talkie is a half-duplex device because only one party can talk at a time. In contrast, a telephone is a full-duplex device because both parties can talk simultaneously. Duplex modes often are used in reference to network data transmissions.
- SCSI
- Short for small computer system interface, a parallel interface standard used by Apple Macintosh computers, PCs, and many UNIX systems for attaching peripheral devices to computers. Nearly all Apple Macintosh computers, excluding only the earliest Macs and the recent iMac, come with a SCSI port for attaching devices such as disk drives and printers.
- parallel interface
- A channel capable of transferring more than one bit simultaneously. Almost all personal computers come with at least one parallel interface. The other type of interface is a serial interfaces.
- serial port
- A port, or interface, that can be used for serial communication, in which only 1 bit is transmitted at a time.
- TFT
- Short for thin film transistor, a type of LCD flat-panel display screen, in which each pixel is controlled by from one to four transistors. The TFT technology provides the best resolution of all the flat-panel techniques, but it is also the most expensive. TFT screens are sometimes called active-matrix LCDs.