Glossary Of Terms

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.

Application – A more technical term for program.

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.

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, data recovery may be needed.

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.

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.

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.

CPU – Stands for Central Processing Unit, a programmable logic device that performs all the instruction, logic, and mathematical processing in a computer.

Cross-linked files – Two files that both refer to the same data. 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. So, it is an error condition in which the FAT indicates that data from two different files occupies the same cluster on a disk. A cluster can contain data for only one file, so cross-linked files indicate an error in the disk’s file structure. Norton Disk Doctor can determine the true owner of the data and correct this type of error.

Data Recovery – is the process of salvaging data from damaged, failed, corrupted, or inaccessible secondary storage media when it cannot be accessed normally. Often the data are being salvaged from storage media formats such as hard disk drives, storage tapes, CDs, DVDs, RAID, and other electronics. Recovery may be required due to physical damage to the storage device or logical damage to the file system that prevents it from being mounted by the host operating system. Although there is some confusion as to the term, data recovery can also be the process of retrieving and securing deleted information from a storage media for forensic purposes.

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%.

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.

Encrypted data – Data converted into cyphertext. Encryption is the safest way to ensure data confidentiality.

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.

Extract – To extract is to return a compressed file to its original state. Typically in order to view the contents of a compressed file, you must extract it first.

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.

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.

Folder – Commonly used as a standard Windows 95/98/NT term, equivalent to the Windows 3.x term directory.

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.

Head – A small electromagnetic device inside a drive that reads, writes, and erases data on the drive’s media.

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 – An essential part of the operating system, responsible for resource allocation, low-level hardware interfaces, security, and more.

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. A path can identify a drive (e.g. C:\), a folder (e.g. C:\Temp) , or a file (e.g. C:\Windows\ftp.exe).

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.

Serial ATA (SATA) – In computer hardware, Serial ATA is a computer bus technology primarily designed for transfer of data to and from hard disks and optical drives. It was designed as a successor to the legacy Advanced Technology Attachment standard (ATA), and is expected to eventually replace the older technology ( retroactively renamed Parallel ATA or PATA). Serial ATA adapters and devices communicate over a high-speed serial link.

SCSI (“Skuzzy”) – SCSI (Small Computer System Interface) is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, and electrical and optical interfaces. SCSI is most commonly used for hard disks and tape drives, but it can connect a wide range of other devices, including scanners, and optical drives (CD, DVD, etc.). The SCSI standard contains definitions of command sets of specific peripheral device types; the presence of “unknown” as one of these types means that in theory it can be used to interface almost any device, but the standard is highly pragmatic and addressed toward commercial requirements.

Sector – The tracks on a disk are divided into sectors. Clusters contains from 1 to 64 sectors.

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.