The following is a list of acronyms which appear on the CompTIA A+ exams. Candidates are encouraged to review the complete list and attain a working knowledge of all listed acronyms as a part of a comprehensive exam preparation program.
AC Alternating Current - In alternating current (AC, also ac), the movement of electric charge periodically reverses direction. In direct current (DC, also dc), the flow of electric charge is only in one direction.
ACPI Advanced Configuration and Power Interface - ACPI defines platform-independent interfaces for hardware discovery, configuration, power management and monitoring. The specification is central to Operating System-directed configuration and Power Management (OSPM), a term used to describe a system implementing ACPI, which removes device management responsibilities from legacy firmware interfaces.
ACT Audio Format - A lossy ADPCM 8 kbit/s compressed audio format recorded by most Chinese MP3 and MP4 players with a recording function, and voice recorders.
ADSL Asymmetrical Digital Subscriber Line - A form of DSL, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voiceband modem can provide.
AGP Accelerated Graphics Port - A high-speed point-to-point channel for attaching a video card to a computer's motherboard, primarily to assist in the acceleration of 3D computer graphics.
AMD Advanced Micro Devices - An American multinational semiconductor company based in Sunnyvale, California, that develops computer processors and related technologies for commercial and consumer markets. Its main products include microprocessors, motherboard chipsets, embedded processors and graphics processors for servers, workstations and personal computers, and embedded systems applications.
APM Advanced Power Management - An API developed by Intel and Microsoft which enables an operating system running an IBM-compatible personal computer to work with the BIOS to achieve power management.
ASR Automated System Recovery - A feature of the Windows XP operating system that can be used to simplify recovery of a computer's system or boot volumes.
ATA Advanced Technology Attachment - An interface standard for the connection of storage devices such as hard disks, floppy drives, and optical disc drives in computers.
ATAPI Advanced Technology Attachment Packet Interface - A protocol that has been applied to ATA that allows a greater variety of devices to be connected to a computer than ATA would allow.
ATX Advanced Technology eXtended - A motherboard form factor specification developed by Intel in 1995 to improve on previous de facto standards like the AT form factor.
A/V Audio Video - Refers to; works with both a sound and a visual component, the production or use of such works, or the equipment used to create and present such works.
BNC Bayonet-Neill-Concelman or British Naval Connector - The BNC connector is used for RF signal (typically pro-video) connections, both for analog and Serial Digital Interface video signals.
BTX Balanced Technology Extended - A form factor for motherboards, originally intended to be the replacement for the aging ATX motherboard form factor in late 2004 and early 2005. It was designed to alleviate some of the issues that arose from using newer technologies (which often demand more power and create more heat) on motherboards compliant with the circa-1996 ATX specification.
CAPTCHA Completely Automated Public Turing Test To Tell Computers and Humans Apart - A type of challenge-response test used in computing as an attempt to ensure that the response is generated by a person. The process usually involves a computer asking a user to complete a simple test which the computer is able to grade. These tests are designed to be easy for a computer to generate, but difficult for a computer to solve, so that if a correct solution is received, it can be presumed to have been entered by a human. A common type of CAPTCHA requires the user to type letters or digits from a distorted image that appears on the screen, and such tests are commonly used to prevent unwanted internet bots from accessing websites.
CCFL Cold Cathode Fluorescent Lamp - Used for backlighting of LCD displays, for example computer monitors and television screens.
CD Compact Disc - An optical disc used to store digital data. Standard CDs have a diameter of 120 millimetres (4.7 in) and can hold up to 80 minutes of uncompressed audio or 700 MB of data.
CD-ROM Compact Disc Read-Only Memory - A pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback.
CD-RW Compact Disc Rewritable - A rewritable optical disc.
CDFS Compact Disc File System - A file system for read-only and write-once CDROMs. The file system provided for the creation, modification, renaming and deletion of files and directories on a write-once media.
CFS Central File System, Common File System, Command File System - The Cooperative File System (CFS) is a new peer-to-peer read-only storage system that provides provable guarantees for the efficiency, robustness, and load-balance of file storage and retrieval.
CMOS Complementary Metal-Oxide Semiconductor - A technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits.
CNR Communications and Networking Riser - A slot found on certain PC motherboards, used for specialized networking, audio, and telephony equipment. A motherboard manufacturer can choose to provide audio, networking, or modem functionality in any combination on a CNR card. CNR slots were once commonly found on Pentium 4-class motherboards, but have since been phased out in favor of on-board or embedded components.
COMx Communication Port (x=port number) - An application or process specific software construct serving as a communications endpoint in a computer's host operating system. A port is associated with an IP address of the host, as well as the type of protocol used for communication and is identified for each address and protocol by a 16-bit number, commonly known as the port number. The port number completes the destination address for a communications session.
CPU Central Processing Unit - The central processing unit (CPU) is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer.
CRIMM Continuity Rambus Inline Memory Mode - The design of many common Rambus memory controllers dictated that memory modules be installed in sets of two. Any remaining open memory slots must be filled with continuity RIMMs (CRIMMs.) These sticks provide no extra memory, and only served to propagate the signal to termination resistors on the motherboard instead of providing a dead end where signals would reflect. CRIMMs appear physically similar to regular RIMMs, except they lack integrated circuits.
CRT Cathode Ray Tube - A vacuum tube containing an electron gun (a source of electrons or electron emitter) and a fluorescent screen used to view images.
DB-25 Serial Communications D-shell Connector, 25 Pins - The D-subminiature or D-sub is a common type of electrical connector. They are named for their characteristic D-shaped metal shield. When they were introduced, D-subs were among the smaller connectors used on computer systems. DB25 denotes a D-sub with a 25-position shell size and a 25-position contact configuration.
DB-9 9 Pin D Shell Connector - The D-subminiature or D-sub is a common type of electrical connector. They are named for their characteristic D-shaped metal shield. When they were introduced, D-subs were among the smaller connectors used on computer systems. DB9 nearly always refers to a 9-pin connector with an E size shell.
DC Direct Current - Direct current (DC) is the unidirectional flow of electric charge. Direct current is produced by sources such as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type.
DDR Double Data-Rate - A computer bus operating with double data rate transfers data on both the rising and falling edges of the clock signal. This is also known as double pumped, dual-pumped, and double transition.
DDR should not be confused with dual channel, in which each memory channel accesses two RAM modules simultaneously. The two technologies are independent of each other and many motherboards use both, by using DDR memory in a dual channel configuration.
DDR RAM Double Data Rate Random Access Memory - A type of very fast computer memory. DDR RAM is based on the same architecture as SDRAM, but utilizes the clock signal differently to transfer twice the data in the same amount of time.
DDR SDRAM Double Data-Rate Synchronous Dynamic Random Access Memory - A class of memory integrated circuits used in computers.
DFS Distributed File System - Any file system that allows access to files from multiple hosts sharing via a computer network. This makes it possible for multiple users on multiple machines to share files and storage resources.
DMA Direct Memory Access - A feature of modern computers that allows certain hardware subsystems within the computer to access system memory independently of the central processing unit.
With DMA, the CPU would initiate the transfer, do other operations while the transfer is in progress, and receive an interrupt from the DMA controller once the operation has been done.
ECC Error Correction Code - An error-correcting code (ECC) or forward error correction (FEC) code is a system of adding redundant data, or parity data, to a message, such that it can be recovered by a receiver even when a number of errors (up to the capability of the code being used) were introduced, either during the process of transmission, or on storage.
Error-correcting codes are frequently used in lower-layer communication, as well as for reliable storage in media such as CDs, DVDs, hard disks, and RAM.
EFS Encrypting File System - A feature introduced in version 3.0 of NTFS that provides filesystem-level encryption. The technology enables files to be transparently encrypted to protect confidential data from attackers with physical access to the computer.
ERD Emergency Repair Disk - A Microsoft Windows Emergency Repair Disk is a specially formatted bootable media that contains information about a particular Windows installation. This disk can be used to restore a computer to a bootable state if the registry or other fundamental system components are damaged due to a malware infection or anything else that could make the operating system unbootable.
Windows 2000 uses what is called an Emergency Repair Disk but it is not bootable. Windows XP uses something very similar to the Windows 2000 Emergency Repair Disk, but it is called Automated System Recovery.
FAT File Allocation Table - A computer file system widely used on computer systems and memory cards. The initial version of FAT designed for 16-bit microprocessors is now referred to as FAT12.
FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of their relative simplicity. FAT was also commonly used on hard disks throughout the DOS and Windows 9x eras, but its use has declined since the introduction of NTFS.
FSB Front Side Bus - A front-side bus is a computer interface used to carry data between the central processing unit (CPU) and a memory controller hub, known as the northbridge. The speed of the front side bus is often used as an important measure of the performance of a computer.
GHz Gigahertz - In computing, most central processing units (CPU) are labeled in terms of their clock rate expressed in megahertz or gigahertz (109 hertz). This number refers to the frequency of the CPU's master clock signal ("Clock rate").
IDE Integrated Drive Electronics - The first version of what is now called the ATA/ATAPI interface was developed by Western Digital under the name Integrated Drive Electronics (IDE).
The term Integrated Drive Electronics refers not just to the connector and interface definition, but also to the fact that the drive controller is integrated into the drive, as opposed to a separate controller on or connected to the motherboard.
ISA Industry Standard Architecture - A computer bus standard for IBM PC compatible computers introduced to support its Intel 8088 microprocessor's 8-bit external data bus and extended to 16 bits for the IBM Personal Computer/AT's Intel 80286 processor.
The ISA bus was further extended for use with 32-bit processors as Extended Industry Standard Architecture (EISA).
JBOD Just a Bunch Of Disks - Used to refer to concatenation, where all the physical disks are concatenated and presented as a single disk. Concatenation or spanning of disks is not one of the numbered RAID levels, but it is a popular method for combining multiple physical disk drives into a single virtual disk. It provides no data redundancy.
Kb kilobit - A multiple of the unit bit for digital information or computer storage equal to 1,000 bits.
KB Kilobyte or knowledge base - A multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol kB or KB have historically been used to refer to either 1024 (210) bytes or 1000 (103) bytes in the fields of computer science and information technology.
LBA Logical Block Addressing - A common scheme used for specifying the location of blocks of data stored on computer storage devices, generally secondary storage systems such as hard disks.
NTFS new technology file system - A proprietary file system developed by Microsoft Corporation for its Windows line of operating systems. NTFS supersedes the FAT file system as the preferred file system for Microsoft�s Windows operating systems.
S/PDIF Sony / Philips Digital Interface Format - A type of digital audio interconnect cable used in consumer audio equipment to output audio over relatively short distances. The signal is transmitted over either a coaxial cable with RCA connectors or a fibre optic cable with TOSLINK connectors. S/PDIF interconnects components in home theatres and other digital high fidelity systems.
SPGA Staggered Pin Grid Array - A type of integrated circuit packaging. In a PGA, the package is square or roughly square, and the pins are arranged in a regular array on the underside of the package. The pins are commonly spaced 2.54 mm (0.1") apart, and may or may not cover the entire underside of the package. PGAs are often mounted on printed circuit boards using the through hole method or inserted into a socket. PGAs allow for more pins per integrated circuit than older packages such as dual in-line package (DIP).
SRAM Static Random Access Memory - A type of semiconductor memory that uses bistable latching circuitry to store each bit. The term static differentiates it from dynamic RAM (DRAM) which must be periodically refreshed. SRAM exhibits data remanence, but is still volatile in the conventional sense that data is eventually lost when the memory is not powered.
SVGA Super Video Graphics Array - A graphics display controller implementing any superset of the standard IBM VGA display adapter. When used as a resolution specification, in contrast to VGA or XGA for example, the term SVGA normally refers to a resolution of 800 � 600 pixels.
SXGA Super Extended Graphics Array - A standard monitor resolution of 1280�1024 pixels.
TB Terabyte - A multiple of the unit byte for digital information. The prefix tera means 1012 in the International System of Units (SI), and therefore 1 terabyte is 1,000,000,000,000 bytes, or 1 trillion bytes, or 1,000 gigabytes.
UAC User Account Control - A technology and security infrastructure introduced with Microsoft's Windows Vista and Windows Server 2008 operating systems, with a more relaxed version also present in Windows 7 and Windows Server 2008 R2. It aims to improve the security of Microsoft Windows by limiting application software to standard user privileges until an administrator authorizes an increase or elevation.
UART Universal Asynchronous Receiver Transmitter - A type of "asynchronous receiver/transmitter", a piece of computer hardware that translates data between parallel and serial forms. UARTs are commonly used in conjunction with communication standards such as EIA, RS-232, RS-422 or RS-485. The universal designation indicates that the data format and transmission speeds are configurable and that the actual electric signaling levels and methods typically are handled by a special driver circuit external to the UART.
UDMA Ultra Direct Memory Access - A method used to transfer data between the computer (through the ATA controller) and an ATA device.
USMT user state migration tool - A Microsoft command line utility program intended to allow advanced users, comfortable with Scripting language, to transfer files and settings between PCs.
UXGA Ultra Extended Graphics Array - A standard monitor resolution of 1600�1200 pixels.
VESA Video Electronics Standards Association - An international standards body for computer graphics formed in 1988.
VFAT Virtual File Allocation Table - A virtual installable files system driver used in Windows for Workgroups and Windows 95. VFAT operates in protected mode and serves as an interface between applications and the File Allocation Table (FAT).
VGA Video Graphics Array - The display hardware first introduced with the IBM PS/2 line of computers in 1987, but through its widespread adoption has also come to mean either an analog computer display standard, the 15-pin D-subminiature VGA connector or the 640�480 resolution itself. While this resolution was superseded in the personal computer market in the 1990s, it is becoming a popular resolution on mobile devices.
VM Virtual Machine - A completely isolated guest operating system installation within a normal host operating system. Modern virtual machines are implemented with either software emulation or hardware virtualization. In most cases, both are implemented together.
VRAM Video Random Access Memory - A dual-ported variant of dynamic RAM (DRAM), which was once commonly used to store the framebuffer in some graphics adapters.
WIFI Wireless Fidelity - A popular technology that allows an electronic device to exchange data wirelessly (using radio waves) over a computer network, including high-speed Internet connections. The Wi-Fi Alliance defines Wi-Fi as any "wireless local area network (WLAN) products that are based on the Institute of Electrical and Electronics Engineers' (IEEE) 802.11 standards".
WINS Windows Internet Name Service - Microsoft's implementation of NetBIOS Name Service (NBNS), a name server and service for NetBIOS computer names. Effectively WINS is to NetBIOS names what DNS is to domain names � a central mapping of host names to network addresses. Like DNS it is broken into two parts, a Server Service (that manages the encoded Jet Database, server to server replication, service requests, and conflicts) and a TCP/IP Client component which manages the client's registration and renewal of names, and takes care of queries.
WLAN Wireless Local Area Network - A wireless local area network (WLAN) links two or more devices using some wireless distribution method (typically spread-spectrum or OFDM radio), and usually providing a connection through an access point to the wider internet. This gives users the mobility to move around within a local coverage area and still be connected to the network. Most modern WLANs are based on IEEE 802.11 standards, marketed under the Wi-Fi brand name.
WUXGA Wide Ultra Extended Graphics Array - A display resolution of 1920�1200 pixels (2,304,000 pixels) with a 16:10 screen aspect ratio.
XGA Extended Graphics Array - An IBM display standard introduced in 1990.
ZIF Zero Insertion Force - A concept used in the design of IC sockets and electrical connectors invented to avoid problems caused by applying force upon insertion and extraction.
ZIP Zigzag Inline Package - A short-lived packaging technology for integrated circuits, particularly dynamic RAM chips. It was intended as a replacement for dual in-line packaging (DIL or DIP). A ZIP is an integrated circuit encapsulated in a slab of plastic, measuring about 3 mm x 30 mm x 10 mm. The package's pins protrude in two rows from one of the long edges. The two rows are staggered by 1.27 mm (0.05"), giving them a zig-zag appearance, and allowing them to be spaced more closely than a rectangular grid would allow. The pins are inserted into holes in a printed circuit board, with the packages standing at right-angles to the board, allowing them to be placed closer together than DIPs of the same size. ZIPs have now been superseded by surface-mount packages such as the thin small-outline packages (TSOPs) used on single-in-line memory modules (SIMMs) and dual-in-line memory modules (DIMMs).