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A20 line - The 21st address line in 286, 386, and 486 processors.

Address - An address is a word or number that refers to a storage location or port.

ALU - The term "ALU" stands for Arithmetical and Logical Unit. It is a part of a CPU, and executes the arithmetical and logical operations.

Analog - The term analog refers to a signal which can take any value within the overall allowable range.

ANSI - Acronym for American National Standards Institute, an organization in the US that sets technical standards.

ASCII - Acronym for American Code for Information Interchange. ASCII is a 7-bit binary code created to allow compatibility amoung various types of computer equipment.

Asynchronous - A data transmission method that does not require a clock synchronization signal for maintaining data integrity. Transmission is characterized by individual characters, surrounded by start and stop bits.

Attenuation - refers to loss in signal strength, due to resistance, absorption, capacitance or any characteristics of the medium.

AUTOEXEC.BAT - An MSDOS configuration file that is automatically executed by DOS during its boot process.

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Batch File - An MSDOS text file that contains one or more DOS commands. When the name of the command file is entered on the command line, DOS executes the commands contained in the file. The .BAT extension is used to identify a batch file.

BAUD - A unit measuring the signaling speed of the data transmission device.

BIOS - An acronym for Basic Input/Output System. I t is a part of an operating system that controls the communication between the computer and its peripherals.

BIT [BInary DigiT] - The smallest unit of data communication information recognized by a computer.

Bootable Disk - A bootable disk contains the boot files of an operating system and is used to "boot" a computer.

Buffer - A block of random access memory [RAM] used to temporarily place data that is being transfered from one device to another.

Bus - An electrical path used to ttransmit control, data and address signals.

Bus Topology - A network in which all nodes share a common pathway called the bus.

Byte - A collection of 7 or 8 continous bits that makes up a character or other discrete item of information.

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Cache Memory - It is a buffer of high-speed memory that temporarily holds data that is being read from or written to the disk drives.

Clock Speed - The operation of the microprocessor is synchronized by a timing pattern generated by the processor itself. This timing pattern is referred to as the clock speed of the processor. The clock speed is measured in megahertz (MHz).

Cluster - Data is stored on disk in clusters. A cluster may be composed of one or more sectors and is the smallest unit of disk space for data storage.

Cold Boot - reloading a computer's operating system by turning the power to the computer off and then back on.

CONFIG.SYS - An MSDOS user created text file that may contain specific commands and parameters that are read during the boot process.

Cylinder - On a hard disk, a cylinder is all the tracks on all the disk platters that lie in the same relative position.

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Data Circuit-terminating Equipment (DCE) - An equipment that establishes, maintains, and terminates a connection, and performs the conversion necessary for communications. For example, in the case of an EIA 232-D connection, the modem is usually considered as DCE.

Data Terminal Equipment (DTE) - An end-user device such as a terminal or computer.

Device Driver - A memory resident-program that is needed by the operating system to control certain hardware devices. In MSDOS, device drivers are loaded into the system by including a command line in the CONFIG.SYS file.

Disk Fragmentation - A disk is said to be fragmented when the data of a file span several sectors, and these sectors are scattered all around the disk.

Dynamic Data Exchange (DDE) - A method of interprocess communications that allows you to exchange commands and data between two applications running simultaneously.

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Erasable Programming Read-Only Memory (EPROM) - It is a type of read-only memory in which data pattern can be erased to allow a new pattern.

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File Allocation Table (FAT) - A portion of all DOS formatted disks that contain information on the number of files and available storage space.

File Server - Contains hardware components that let users, computers and devices such as disks and printers exchange and access information on the network.

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Giga - Designation for one billion.

Gigahertz (GHz) - An analog frequency unit equal to one billion hertz.

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Hertz - The number of cycles per second.

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IRQ - Are used by the Input/Output devices to communicate with a CPU. IRQs on ISA machines cannot be shared by two devices.

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Jumpers - It is a series of pins protruding from a circuit board onto which a contact block is placed. Jumpers are used to select various circuit options.

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Kilo (K) - Designation for one thousand.

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Latency - The amount of time a drive must wait before a specified bit of data rotates under the heads.

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Mega (M) - Designation for one million.

Megabyte (Mbyte) - 1,048,576 bytes, equal to 1024 Kbytes.

Megahertz (MHz) - A unit of analog frequency equal to 1 million Hz.

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Nanosecond - One-billionth of a second : 0.000000001.

Null Modem - A cable which interchanges wire positions, so that a DTE device looks like a DCE or vice versa.

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Object Linking and Embedding (OLE) - Is an enhancement to DDE process that allows you to link data created in one application to a document created in another application. It also allows you to edit that data in the original application without leaving the compound document.

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Parity - An error-dectecting scheme which uses an extra checking bit, called the parity bit, to allow the receiver to determine whether there has been an error in the received data bits.

Parity Error - An error indicator that is signaled when the actual parity of the received data does not agree with the parity value indicated by the parity bit.

Partition - An electronic division of a hard disk that must be created before the disk can be formatted. Each division or area is considered by the operating system to be a separate drive.

Protected Mode - An operating mode for the Intel 80x86 and higher processors that supports multitasking, data security and virtual memory.

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QWERTY Keyboard - A keyboard with the characters Q, W, E, R, T, and Y on top row of alpha keys.

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Real Mode - Is the "Power On" mode of the Intel 80x86 processors in which the processor emulates the 8086 and 8088 microprocessors. Real Mode has no memory protection and the maximum amount of physical address space is 1 MB.

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Start Bit - The first bit in asynchronous communication.

Stop Bit - The last bit in asynchronous communication.

Synchronous - A communication method in which the data flows continuously, without start and stop bits and the receiver must synchronize to the timing of the transmitter.

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Timeslicing - A method of multitasking that allocates CPU time to tasks.

Track - A concentric ring encoded on a disk during the low-level format.

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Universal Asynchronous Receiver/Transmitter (UART) - Is a chip with serial/parallel conversion. parallel/serial conversion, and other facilities designed for use in asynchronous serial communication.

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Virtual Memory - A technique of simulating additional memory for an application to use.

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Waite State - The pausing of CPU processing allowing memory time to catch up with data delivery requests.

Warm Boot - A complete reload of computer's operating system through use of the system reset keys on the keyboard.

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XMS - Is a Microsoft specification that provides a way for real mode applications to access extended memory.

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Yellow Book - A standard used by CD-ROM technology. It specifies how digital information is to be stored on the CD-ROM and read by the computer.

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Zero Code Suppression - A method of inserting a "ONE" bit to prevent the transmission of number of consecutive "ZERO" bits.