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Glossary A Glossary of Select Computer Terms
Term Definition
Adapter A device that serves as an interface between the system unit and a device attached to it, such as a SCSI Adapter.   Often synonymous with expansion card, card, or board.  Can also refer to a special type of connector.
Anti-Virus Software that detects, repairs, cleans, or removes virus-infected files from a computer.
Bank The collection of memory chips or modules that make up a block of memory.  This can be 1, 2 or 4 chips.  Memory in a PC must always be added or removed in full-bank increments.
BIOS The part of the operating system that provides the lowest level interface to peripheral devices.  The BIOS is stored in the ROM on the computer's motherboard.
Boot To start up your computer.  Because the computer gets itself up and going from an inert state, it could be said to lift itself up "by its own bootstraps" -- this is where the term 'boot' originates.
Boot Disk The magnetic disk (usually a hard disk) from which an operating system kernel is loaded (or "bootstrapped").  MS-DOS and Microsoft Windows can be configured (in the BIOS) to try to boot off either floppy disk or hard disk, in either order (and on some modern systems even from CD or other removable media).  A special floppy boot disk (often called a System Rescue Disk) can be created that will allow your computer to boot even if it cannot boot from the hard disk.  Go into Windows/Control Panel/Add-Remove Programs to make this disk.
Boot Record Once the BIOS determines which disk to boot from, it loads the first sector of that disk into memory and executes it.   Besides this loader program, the Boot Record contains the partition table for that disk.  If the Boot Record is damaged, it can be a very serious situation!  There are some good disk utility programs available that can actually recover your hard drive and it's data if the boot record should become damaged.
Boot Sector See Boot Record.
Bootstrap To load and initialize the operating system on a computer.  Often abbreviated to boot. 
Bus A set of conductors (wires or connectors in an integrated circuit) connecting the various functional units in a computer.  There are busses both within the CPU and connecting it to external memory and peripheral devices.  The bus width (i.e., the number of parallel connectors) is one factor limiting a computer's performance.
Card A circuit board that usually is designed to plug into a connector or slot.  See also adapter.
Cluster Windows allocates space to files in units called clusters.  Each cluster contains from 1 to 64 sectors, depending on the type and size of the disk.  A cluster is the smallest unit of disk space that can be allocated for use by files.  Windows Scan Disk can maintain your hard drive and locate lost clusters, either recycling them as free space or making them into files so you can review the data.
CMOS A part of the motherboard that maintains system variables in static RAM.  It also supplies a real-time clock that keeps track of the date, day and time.  CMOS Setup is typically accessible by entering a specific sequence of keystrokes during the POST at system start-up.
Cold Boot Starting or restarting a computer by  turning on the power supply.  See also warm boot.
CPU Stands for Central Processing Unit, a programmable logic device that performs all the instruction, logic, and mathematical processing in a computer.
Crash A sudden, usually drastic failure.  Can be said of the operating system or a particular program when there is a software failure.  Also, a disk drive can crash because of hardware failure.  There are "crash detection" programs available, although few can really fully protect your system from crashing... most can only recover in a limited way.
Cross-linked files Two files that both refer to the same data.
Defragment As modern file systems are used and files are deleted and created, the total free space becomes split into smaller non-contiguous blocks.  Eventually new files being created, and old files being extended, cannot be stored each in a single contiguous block but become scattered across the file system.  This degrades performance as multiple seek operations are required to access a single fragmented file. 

Defragmenting consolidates each existing file and the free space into a contiguous group of sectors.  Access speed will be improved due to reduced seeking.  A nearly-full disk system will fragment more quickly.   A disk should be defragmented before fragmenting reaches 10%.  Windows has a good built in defragment program as part of its built in utility package.  You need to do it regularly.  Once a month is recommended.

Directory This is an index into the files on your disk.  It acts as a hierarchy, and you will see them represented in Windows looking like manila folders.
DMA Stands for direct access memory.  DMA is a fast way of transferring data within a computer.  Most devices require a dedicated DMA channel (so the number of DMA channels that are available may limit the number of peripherals that can be installed).
DRAM Dynamic Random Access Memory (see also SDRAM).  A type of memory used in a PC for the main memory (such as your "32 Mbytes of RAM".)  "Dynamic" refers to the memory's memory of storage - basically storing the charge on a capacitor.  Specialized types of DRAM (such as EDO memory) have been developed to work with today's faster processors.
Driver A program designed to interface a particular piece of hardware to an operating system or other software.
DOS Disk Operating System.  Usually used as an abbreviation for MS-DOS, a micro-computer operating system developed by Microsoft.
EIDE Stands for enhanced integrated drive electronics.  A specific type of attachment interface specification that allows for high-performance, large-capacity drives.  See also IDE.
Executable A binary file containing a program in machine language which is ready to be executed (run).  MS-DOS and Windows machines use the filename extension ".exe" for these files.
Expansion Card An integrated circuit card that plugs into an expansion slot on a motherboard to provide access to additional peripherals or features not built into the motherboard.  See also adapter.
FAT See File Allocation Table.
FAT32 See File Allocation Table.
FDISK The disk-partitioning program used in DOS and several other operating systems to create the master boot record and allocate partitions for the operating system's use.
File A collection of data grouped into one unit on a disk.
File Allocation Table (FAT or FAT32)  DOS uses the FAT to manage the disk data area.  The FAT tells DOS which portions of the disk belong to each file.  The FAT links together all of the clusters belonging to each file, no matter where they are on disk.  The FAT is a critical file: you should be sure to back it up regularly.

FAT32 is a newer type of FAT that was designed to handle large hard disks.  The older FAT (FAT16) can only support partitions up to two gigabytes in size.  FAT32 can handle partitions that are thousands of gigabytes.

File System A system for organizing directories and files, generally in terms of how it is implemented in the disk operating system.
Firmware Software contained in a read-only memory (ROM) device.
FORMAT The DOS format program that performs high-level formatting on a hard disk, and both high- and low-level formatting on a floppy disk.
Fragmentation The state of having a file scattered around a disk in pieces rather than existing in one contiguous area of the disk.  Fragmented files are slower to read than unfragmented files.
Graphics Adapter See Video Adapter
Head A small electromagnetic device inside a drive that reads, writes, and erases data on the drive's media.
Heat Sink A mass of metal attached to a chip carrier or socket for the purpose of dissipating heat.
<font face="Arial">IDE Stands for integrated drive electronics.  Describes a hard disk with the disk controller integrated within it.   See also EIDE.
I/O Port I/O stands for input/output.   I/O is the communication between a computer and its user, its storage devices, other computers (via a network) or the outside world.  The I/O port is the logical channel or channel endpoint in an I/O communication system.
IRQ Stands for interrupt request.   IRQ is the name of the hardware interrupt signals that PC peripherals (such as serial or parallel ports) use to get the processor's attention.  Since interrupts usually cannot be shared, devices are assigned unique IRQ addresses that enable them to communicate with the processor.  Peripherals that use interrupts include LAN adapters, sound boards, scanner interfaces, and SCSI adapters. 
Jumper A small, plastic-covered metal clip that slips over two pins protruding from a circuit board.  When in place, the jumper connects the pins electronically and closes the circuit, turning it "on".
Kernel An essential part of the operating system, responsible for resource allocation, low-level hardware interfaces, security, and more.
Lost Cluster Chain This is a cluster on disk that is not registered as free, but does not have any known data in it.
Motherboard The "heart" of your PC -- it handles system resources (IRQ lines, DMA channels, I/O locations), as well as core components like the CPU, and all system memory.  It accepts expansion devices such as sound and network cards, and modems.
NTFS Windows NT File System.
Partition A logical section of a disk.  Each partition normally has its own file system.
Partition Table A 64-byte data structure that defines the way a PC's hard disk is divided into logical sectors known as partitions. The partition table describes to the operating system how the hard disk is divided.  Each partition on a disk has a corresponding entry in the partition table.  The partition table is always stored in the first physical sector of a disk drive.
Path A location of a file.  The path consists of directory or folder names, beginning with the highest-level directory or disk name and ending with the lowest-level directory name.
Peripheral Any part of a computer other than the CPU or working memory (RAM and ROM).  For example, disks, keyboards, monitors, mice, printers, scanners, tape drives, microphones, speakers, and other such devices are peripherals.
Plug-and-Play (PnP)  A hardware and software specification developed by Intel that allows a PnP system and a PnP adapter to configure automatically .  PnP cards generally have no switches or jumpers, but are configured via the PnP system's BIOS or with supplied software for non-PnP computers.
POST Stands for power-on self test.   Each time a PC initializes, the BIOS executes a series of tests collectively known as the POST.  The test checks each of the primary areas of the system, including the motherboard, video system, drive system, and keyboard, and ensures that all components can be used safely.  If a fault is detected, the POST reports it as an audible series of beeps or a hexadecimal code written to an I/O port.
RAM Random Access Memory (see also DRAM, SDRAM).  A data storage device for which the order of access to different locations does not affect the speed of access.  This is in contrast to magnetic disk or magnetic tape where it is much quicker to access data sequentially because accessing a non-sequential location requires physical movement of the storage medium rather than just electronic switching.  The most common form of RAM in use today is built from semi-conductor integrated circuits, which can either be static (SRAM) or dynamic (DRAM).
Registry See System Registry
ROM Read-Only Memory.  A type of data storage device which is manufactured with fixed contents.  The term is most often applied to semiconductor integrated circuit memories.  ROM is inherently non-volatile storage - it retains its contents even when the power is switched off, in contrast to RAM.  It is used in part for storage of the lowest level bootstrap software (firmware) in a computer.
SCSI Stands for small computer system interface.  A standard that allows multiple devices to be connected in daisy-chain fashion.
SDRAM Stands for synchronous dynamic random Access memory (see also DRAM).  SDRAM incorporates new features that make it faster than standard DRAM and EDO memory.
Sector The tracks on a disk are divided into sectors.  Clusters contains from 1 to 64 sectors.
Slot A physical connector on a motherboard to hold an expansion card, SIMM, DIMM, or a processor card in place.
Socket A receptacle, usually on a motherboard, that processors or chips can be inserted into.
System Registry The system configuration files used by Windows 95, 98 and NT to store settings about user preferences, installed software, hardware and drivers, and other settings required for Windows to run correctly.  The system updates the registry every time you add new hardware or a new program to your system.  When the registry becomes "broken," it can cause serious system problems.
System Rescue Disk See Boot Disk.
Terminator Most commonly found in relation to a SCSI chain, this functions to prevent the reflection or echoing of signals that reach the ends of the SCSI bus.  Usually terminators are hardware circuits or jumpers.
Video Adapter An expansion card or chip set built into a motherboard that provides the capability to display text and graphics on the computer's monitor.  If the adapter is part of an expansion card, it also includes the physical connector for the monitor cable.  If it is a chip set on the motherboard, the video connector will be on the motherboard also.
Virus A virus is a program written to cause mischief or damage to a computer system.  A mild virus might only be a slight nuisance, or even amusing.  However, most viruses do damage, whether to your files, your registry, or even your hardware.  Viruses are hard to detect, easy to propagate, and difficult to remove.  Your computer can pick up a virus when you copy a seemingly normal file from a diskette or download it from the Internet.
Warm Boot Rebooting a system by means of a software command as opposed to turning the power off and on.  See also cold boot.
Y2K Y2K (Year 2000) is the common name for all the difficulties the turn of the century may bring to computer users.  Back in the seventies and eighties the turn of the century looked so remote and memory and disk space were so expensive that most programs stored only the last two digits of the years.  Those which will still be in use will produce surprising results after 2000: they may believe that 1 January 2000 is 1 January 1900, they may calculate the day of the week wrong, etc.  In addition, serious problems may occur when the internal clocks in your system fail to roll-over.
Disclaimer:  These pages are provided for information purposes only.  We cannot be held responsible for any damage you might inflict on your system while using the information contained herein.  We recommend you always refer any technical matter that is "over your head" to a qualified computer technician.

2011 Double-Hammer Computer Services.  All rights reserved.
Last Updated: September 04, 2011

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