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MSC - PC and Internet glossary
Category: Technical and IT > PC and Internet
Date & country: 15/11/2007, UK
Words: 147

Access Time
The required time to read or write data to RAM or other storage device. Since the operating environment and varying conditions affect access time, this is usually given as an average.

In serial port modem communications, A control code (06h) sent to a sending station or computer by the receiving unit to acknowledge either that the receiver is ready to accept transmissions or that transmitted data arrived without error. The ability to receive and send acknowledgment signals is built into the hardware and software. For example, th

ACPI(Advanced Configuration and Power Interface) is an industry specification for the efficient handling of power consumption in desktop and mobile computers. ACPI specifies how a computer's BIOS, operating system and peripherals communicate with each other about power usage. ACPI allows the following capabilities (assuming the operating system sup

The term used to describe expansion cards that are inserted into bus expansion slots.

Adapter Card
A flat rectangular fiberglass board with electronic circuitry. Inserted in an expansion slot on the computer main bus, it provides additional system functions, such as device controllers or video adapters. Also called an Add-In card.

Every memory location is numbered consecutively. This number is the address of the memory location. An address can be a label, number, or name that identifies a register, memory location, or a location on a disk drive or external device accessed via an I/O port.

Apple Filing Protocol

AGP (Advanced Graphics Port)
An interface specification that enables 3-D graphics to display quickly on ordinary personal computers. AGP is an interface designed to convey 3-D images (for example, from Web sites or CD-ROMs) much more quickly and smoothly than is possible today on any computer other than an expensive graphics workstation. The interface uses your computer's main

A term used to describe any device that represents values by a continuously varied physical property, such as voltage.

Short for Advanced Power Management, an API developed by Intel and Microsoft that allows developers to include power management in BIOSes. APM defines a layer between the hardware and the operating system that effectively shields the programmer from hardware details.

Inexpensive LAN Architecture Built into Apple Macintosh Computers and Laser Printers

A process where devices compete for possession of the channel on a prioritized basis.

Refers to the way a system is designed and how the components are connected with each other. There are computer architectures, network architectures and software architectures.

An array of disk drives combines the storage space on the disk drives into a single segment of contiguous storage space. MegaRAID can group disk drives on one or more SCSI channels into an array. A hot spare drive does not participate in an array.

Array Management Software
Software that provides common control and management for a disk array. Array Management Software most often executes in a disk adapter or intelligent host bus adapter, but can also execute in a host server. When it executes in a disk adapter or adapter, Array Management Software is often called firmware.

Array Spanning
Array spanning by a logical drive combines storage space in two arrays of disk drives into a single, contiguous storage space in a logical drive. MegaRAID logical drives can span consecutively numbered arrays that each consist of the same number of disk drives. Array spanning promotes RAID levels 1, 3, and 5 to RAID levels 10, 30 and 50, respective

Asynchronous Data Transfer
Data transfer (usually at a low rate and independent of any external timing constraints) performed by a SCSI device involving the interlocking of a signal to the initiator (REQ) and a signal to the target (ACK) such that each step of the data transfer protocol must occur before the next step can begin.

Asynchronous Event Notification
A process when a SCSI target can send unsolicited sense information to an initiator using the SCSI SEND command.

Asynchronous Operations
Those operations that bear no relationship to each other in time and can overlap. The concept of asynchronous I/O operations is central to independent access arrays in throughput-intensive applications.

Advanced Technology. Specifically refers to the IBM PC AT incorporating the Intel 80286 processor. It is also used as a reference of BIOS compatibility. AT refers to the original IBM PC/AT computer architecture, more commonly known as ISA now.

ATA - AT Attachment
A disk drive implementation that integrates the controller on the disk drive itself. There are several versions of ATA, all developed by the Small Form Factor (SFF) Committee: ATA: Known also as IDE, supports one or two hard drives, a 16-bit interface and PIO modes 0, 1 and 2. ATA-2: Supports faster PIO modes (3 and 4) and multiword DMA modes (1 an

ATAPI (AT Attachment Packet Interface) is an interface between your computer and attached CD-ROM drives and tape backup drives. Most of today's PC computers use the standard Integrated Drive Electronics (IDE) interface to address hard disk drives. ATAPI provides the additional commands needed for controlling a CD-ROM player or tape backup so that y

ATX is an industry-wide open specification for a desktop computer's motherboard. ATX improves the motherboard design by taking the small AT motherboard that has been an industry standard and rotating by 90 degrees the layout of the microprocessor and expansion slots. This allows space for more full-length add-in cards. A double-height aperture is s

A unit of measurement of the discrete number of signal elements that can be transmitted per second by a device. It is not an exact measure of the amount of information being transmitted and is not the same as Bits Per Second.

Bios Boot Specification - A Plug and Play BIOS format that enables the user to determine the boot sequence.

The base two numbering system, where the only digits are 0 and 1. It is used by all computers.

Binary Coded Decimal
A method of encoding decimal digits into four binary bits.

BIOS(Basic Input/output system) is the program a personal computer's microprocessor uses to get the computer system started after you turn it on. It also manages data flow between the computer's OS and attached devices such as the hard disk, video adapter, keyboard, mouse and printer. BIOS is an integral part of the computer and comes with it when

BIOS Setup
A utility provided by BIOS in POST. This is where users change parameters that affect the BIOS & system configuration. Also known as CMOS Setup, since the data is stored in CMOS memory.

A binary digit that can take either the value 0 or 1. A bit is the smallest unit of information that a computer can process. Bits are often used to measure transfer speeds. This can be noted in bits per second (bps).

An amount of data moved or addressed as a single unit; the smallest amount of data that can be read or written at a time. Blocks are separated by physical gaps, or identified by their track/sector addresses or logical addresses.

The process of initializing, testing and configuring a computer system from start-up.

BPS - Bits per Second
The number of binary digits that can be transmitted in one second. Generally, modem speeds are given in BPS, not baud rate. Neither baud rate nor BPS take into account the gaps between transmissions, so neither baud rate nor BPS accurately express the amount of information being transferred.

A term used to identify a motherboard component that ties one bus to another. A PCI-to-PCI bridge will tie two PCI busses together. A PCI-to-CardBus bridge will tie PCI and CardBus together.

An area of memory or storage that is temporarily reserved for I/O processing.

Burst Mode
A method of data transfer that allows a device to remain inactive for long periods of time and then send large amounts of data in a short time without interruption. Can be used for DMA transfers on the EISA bus.

(1) A collection of wires through which data is transmitted from one part of a computer to another. You can think of a bus as a highway on which data travels within a computer. When used in reference to personal computers, the term bus usually refers to internal bus. This is a bus that connects all the internal computer components to the CPU and ma

Bus Free Phase
The phase when no SCSI device is actively using the SCSI bus and the bus is available for use.

Bus Mastering
Refers to a feature supported by some bus architectures that enables a controller connected to the bus to communicate directly with other devices on the bus without going through the CPU. Most modern bus architectures, including PCI, support bus mastering because it improves performance.

A unit of data made up of eight contiguous bits. A byte is usually the smallest addressable unit of memory. This is considered to be the basic storage for ‘characters` on a PC. Bytes are used to represent storage size, including memory. Larger groups of bytes are annotated as follows: Kilobyte (KB) 1 KB = 1,024 bytes Megabyte (MB) 1 MB = 1,024 KB

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. A memory cache, sometimes called a cache store or RAM cache, is a portion of memory made of high-speed

CardBus is a 32-bit extension to PCMCIA, which gives card devices similar performance to PCI devices.

The Common Diagnostics Model (CDM) is a standard enabling building blocks that allows to easily integrate 'plug-in' diagnostic modules into management applications. It defines the methodology for adding diagnostics to the Common Information Model (CIM). This allows clients to run diverse diagnostics meant for different devices over a single, unifor

A term used to describe the northbridge and southbridge combination on the motherboard.

Common Internet File System - File Sharing Protocol Used in Windows-Based Networks

The Common Information Model (CIM) schema, Developed by the DMTF, is a very broad approach to the management of systems and networks that applies the object-oriented paradigm.

Connecting two or more computers together in such a way that they behave like a single computer. Clustering is used for parallel processing, for load balancing and for fault tolerance. Clustering is a popular strategy for implementing parallel processing applications because it enables companies to leverage the investment already made in PCs and wo

CMOS is a type of memory. CMOS stands for “complementary metal-oxide semiconductor�, describing the physical arrangement of cells within the memory device. On a standard PC motherboard, CMOS is used to hold data that is accessed by BIOS Setup. The CMOS memory is maintained when the system is off by a battery backup.

Coercion of Drives
The ability to coerce a drive into taking on a specific size. At AMI, drive coercion refers to the ability of our controllers to recognize the sizes of the drives connected, and to then coerce the larger drives to use only that amount of space which the smallest has available. So, if there is a 10GB drive connected with a 15GB drive, and they are c

A device that controls the transfer of data from a computer to a peripheral device and vice versa. For example, disk drives, display screens, keyboards, and printers all require controllers. In personal computers, the controllers are often single chips. When you purchase a computer, it comes with all the necessary controllers for standard component

CPU (Central Processing Unit)
Is an older term for processor and microprocessor, the central unit in a computer containing the logic circuitry that performs the instructions of a computer's programs.

Double Data Rate SDRAM can theoretically improve RAM speed to at least 200 MHz. It activates output on both the rising and falling edge of the system clock rather than on just the rising edge, potentially doubling output. This is expected to be the next predominant type of PC memory.

The dynamic host configuration protocol is an addressing protocol for TCP/IP networks. IP addresses are leased to individual computers on the network from a DHCP server. DHCP allows users to move to different locations on a network without having to bother a network administrator to manually assign a new IP address. DHCP is useful in homes with sev

DIMM (Dual In-Line Memory Module)
A double SIMM (Single In-Line Memory Module). Like a SIMM, it's a module containing one or several random access memory (RAM) chips on a small circuit board with pins that connect it to the computer motherboard. A SIMM typically has a 32 data bit (36 bits counting parity bits) path to the computer that requires a 72-pin connector. For synchronous d

Disk Mirroring
Also known as RAID Level 1. A form of RAID in which the Array Management Function maintains two or more identical copies of data on separate disks. Also known as RAID Level 1 and disk shadowing.

Disk Spanning
Disk spanning allows multiple disk drives to function like one big drive. Spanning not only overcomes disk space shortage; it also simplifies storage management by combining existing resources or adding relatively inexpensive resources. For example, four 400 MB disk drives can be combined to appear to the operating system as one single 1600 MB driv

Disk Striping
Also known as RAID Level 0. A mapping technique in which fixed-size consecutive ranges of virtual disk data addresses are mapped to successive array members in a cyclical pattern.

Abbreviation of direct memory access, a technique for transferring data from main memory to a device without passing it through the CPU. Computers that have DMA channels can transfer data to and from devices much more quickly than computers without a DMA channel can.

DMI (Desktop Management Interface)
An industry framework for managing and keeping track of hardware and software components in a system of personal computers from a central location. DMI was created by the Desktop Management Task Force (DMTF) to automate system management and is particularly beneficial in a network computing environment where dozens or more computers are managed. DM

Domain Name System - Internet Service that Translates Domain Names into IP Addresses. Every time you use a domain name, a DNS server must translate the name into the corresponding IP address.

Dynamic RAM (DRAM) uses a kind of capacitor that needs frequent power refreshing to retain its charge. Because reading a DRAM discharges its contents, a power refresh is required after each read. Apart from reading, just to maintain the charge that holds its content in place, DRAM must be refreshed about every 15 microseconds. DRAM is the least exp

A program that extends the capabilities of a computer by enabling the computer to operate peripheral devices, such as WORM drives, CD-ROM drives, or tape drives.

(Error Correction [or Correcting] Code; Error Checking and Correcting) Allows data that is being read or transmitted to be checked for errors and, when necessary, corrected 'on the fly.' It differs from parity-checking in that errors are not only detected but also corrected. ECC is increasingly being designed into data storage and transmission hard

Extended Data Output Dynamic Random Access Memory. A type of DRAM that is faster than conventional DRAM. Unlike conventional DRAM which can only access one block of data at a time, EDO RAM can start fetching the next block of memory at the same time that it sends the previous block to the CPU.

Extended Industry Standard Architecture. A bus architecture designed for PCs using an Intel 80386, 80486, or Pentium microprocessor. EISA buses are 32 bits wide and support multiprocessing. The EISA bus was designed by nine IBM competitors (sometimes called the Gang of Nine): AST Research, Compaq Computer, Epson, Hewlett-Packard, NEC, Olivetti, Tan

Fibre - Fibre channel
A serial data transfer architecture developed by a consortium of computer and mass storage device manufacturers and now being standardized by ANSI. The most prominent Fibre Channel standard is Fibre Channel Arbitrated Loop (FC-AL). FC-AL was designed for new mass storage devices and other peripheral devices that require very high bandwidth. Using o

Programming inserted into programmable read-only memory (PROM), thus becoming a permanent part of a computing device. Firmware is created and tested like software (using microcode simulation). When ready, it can be distributed like other software and, using a special user interface, installed in the programmable read-only memory by the user. Is som

Flash Memory
Flash memory (sometimes called 'flash RAM') is a type of constantly powered nonvolatile memory that can be erased and reprogrammed in units of memory called blocks. It is a variation of electrically erasable programmable read-only memory (EEPROM) that, unlike flash memory, is erased and rewritten at the byte level, which is slower than flash memory

Front side bus â€` the physical interface between processor and main memory in Intel chipsets.

File Transfer Protocol

Hot Plug (Hot Swap)
The ability to add and remove devices to a computer while the computer is running and have the operating system automatically recognize the change. Two new external bus standards -- Universal Serial Bus (USB ) and IEEE 1394 -- support hot plugging. This is also a feature of PCMCIA. Hot plugging is also called hot swapping.

Circuitry added to a processor that enables it to appear as two logical processors, resulting in a single physical processor appearing like two logical processors to an operating system and multi-threaded application. Each logical processor can execute a thread of a multi-threaded program. Hyper-threading is Intel's simultaneous multi-threading des

HyperTransportâ„¢ technology is a high speed, high performance chip-to-chip interconnect primarily intended for use on a system board within distances of up to 24 inches. The specification has been proposed by Advanced Micro Devices and is promoted by the Hypertransport Consortium.HyperTransportâ„¢ technology is designed to transfer data at 6.4 Gigabyt

I-O (Input-Output)
Describes any operation, program or device that transfers data to or from a computer. A typical I/O device includes a printer, hard disk, keyboard and mouse. Some devices are basically input-only devices (keyboard and mouse); others are primarily output-only devices (printer) and others provide both input and output of data (hard disk, diskette, wr

I-O Controller Hub (ICH)
Equivalent to the Southbridge in Intel`s Hub Architecture. Hub architecture components are linked using a high-speed “hub link� bus, rather than the Northbridge`s PCI bus.

I20 - Intelligent I-O
A fairly new I/O architecture developed by a consortium of computer companies called the I2O special Interest Group (SIG). I2O is designed to eliminate I/O bottlenecks by utilizing special I/O processors (IOPs) that handle the nitty gritty details of interrupt handling, buffering and data transfer. In addition, an I2O driver consists of an OS-speci

Merced is the code name for a new 64-bit microprocessor from Intel that will begin to appear in new workstations and enterprise servers over the next few years. It's the first of Intel's IA-64 series and, because of its greatly increased I/O bandwidth relative to today's 32-bit microprocessors, it will make possible visual computing or the ability

IDE (Integrated Drive Electronics)
A standard electronic interface used between a computer motherboard's data paths or bus and the computer's disk storage devices. The IDE interface is based on the IBM PC ISA 16-bit bus standard, but it is also used in computers that use other bus standards. Most computers sold today use an enhanced version of IDE called EIDE. IDE gets its name beca

IDE disks with Ultra DMA can now run at up to 33Mb/s, but because they can not be daisy-chained in the same way as SCSI and Fibre drives, they require a special RAID controller. The RAID controllers uses Ultra-Wide SCSI for a host channel, because IDE has a very limited cable length and less bandwidth, so although IDE disks are used, the RAID appea

IEEE 1394
A very fast external bus * standard that supports data transfer rates of up to 400 Mbps (400 million bits per second). Products supporting the 1394 standard go under different names, depending on the company. Apple, which originally developed the technology, uses the trademarked name FireWire. Other companies use other names, such as and Lyn

(1) With hardware, initializing a disk means formatting it. (2) In programming, initialize means to assign a starting value to a variable. (3) Initialize can refer to the process of starting up a program or system.

An interrupt is a signal informing a program that an event has occurred. When a program receives an interrupt signal, it takes a specified action (which can be to ignore the signal). Interrupt signals can cause a program to suspend itself temporarily to service the interrupt. Interrupt signals can come from a variety of sources. For example, every

Intelligent Platform Management Interface (IPMI) is a hardware level interface specification that defines a common, abstracted, message-based interface to platform monitoring and control functions. As a hardware-level interface, it sits at the bottom of a typical management software stack. Thus, IPMI is “management software neutral.� It can be expo

IP Security - Set of Protocols Developed to Support a Secure Exchange of Packets at the IP Layer; Has Been Deployed Widely to Implement Virtual Private Networks (VPNs)

Internetwork Packet Exchange - Networking Protocol used by the Novell NetWare OS

Interrupt request line- Each device connected to a computer (microprocessor) must have a specified interrupt line value. With Plug-and Play (PnP), users do not need to set IRQ values manually (or be aware of them) when adding a new device to a computer. BIOS specifies IRQ routing tables for them.

LAN (Local Area Network)
A network of interconnected workstations sharing the resources of a single processor or server within a relatively small geographic area. Typically, this might be within the area of a small office building. However, FDDI extends a local area network over a much wider area. Usually, the server has applications and data storage that are shared in com

High-density diskette technology from Imation Corporation. A SuperDisk diskette can have 2,490 tracks, as opposed to the 135 tracks that conventional 3.5-inch 1.44 MB diskettes use. This higher density translates into 120 MB capacity per diskette.

MDRAM (Multibank Dynamic RAM)
A type of video RAM, developed by MoSys, that divides memory into multiple 32 KB parts or 'banks' that can be accessed individually. Traditional video RAM is monolithic; the entire frame buffer is accessed at one time. Having individual memory banks allows accesses to be interleaved concurrently, increasing overall performance. It's also cheaper si

Memory Controller Hub (MCH)
Equivalent to the Northbridge in Intel`s Hub Architecture. Hub architecture components are linked using a high-speed “hub link� bus, rather than the Northbridge`s PCI bus.

Short for disk mirroring; Also known as RAID Level 1. A form of RAID in which the Array Management Function maintains two or more identical copies of data on separate disks. Also known as RAID Level 1 and disk shadowing.

The physical arrangement in a computer that contains the computer's basic circuitry and components. On the typical motherboard, the circuitry is imprinted or affixed to the surface of a firm planar surface and usually manufactured in a single step. The most common motherboard design in desktop computers today is the AT, based on the IBM AT motherbo

(MultiProcessing Specification) A specification from Intel for designing SMP-based PCs using its Pentium processors. It defines how memory and interrupts are shared.

NetWare Core Protocol - A Set of Server Protocols Available in the Novell NetWare Network Software. An Interface to Request Network Services from Hosts that Provide Services.

NetBios Enhanced User Interface - An Enhanced Version of the NetBIOS Protocol Used by Network Operating Systems Like LAN Manager, LAN Server, Windows for Workgroups, Windows 95/NT

Network File System - Most Common File Sharing Protocol Used in UNIX OSes

Non-maskable Interrupt (NMI)
The non-maskable interrupt (NMI) is used for serious conditions that demand the processor's immediate attention. The NMI cannot be ignored by the system unless it is shutoff specifically. Any other standard interrupt request can be ignored. When an NMI signal is received, the processor immediately drops whatever it was doing and attends to it. The

Northbridge is a chipset component that communicates with the computer processor and controls interaction with memory, the Peripheral Component Interconnect (PCI) bus, and all Accelerated Graphics Port (AGP) activities. Northbridge communicates with the processor using the frontside bus (FSB). Northbridge is one part of a two-part chipset.

Network Time Protocol

OLCE - Online Capacity Expansion
Provides the capability of adding drive space to existing arrays without the need for rebooting the system. When using OLCE, the system dynamically reallocates the existing information, while realigning the array to provide for the additional drive(s).