Computer Terms

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10Base2 – Ethernet specification for thin coaxial cable, transmits signals at 10 Mbps (megabits per second) with a distance limit of 185 meters per segment.

10Base5 – Ethernet specification for thick coaxial cable, transmits signals at 10 Mbps (megabits per second) with a distance limit of 500 meters per segment.

10BaseF – Ethernet specification for fiber optic cable, transmits signals at 10 Mbps (megabits per second) with a distance limit of 2000 meters per segment.

10BaseT – Ethernet specification for unshielded twisted pair cable (category 3, 4, or 5), transmits signals at 10 Mbps (megabits per second) with a distance limit of 100 meters per segment.

100BaseT – Ethernet specification for unshielded twisted pair cabling that is used to transmit data at 100 Mbps (megabits per second) with a distance limit of 100 meters per segment.

1000BaseTX -Ethernet specification for unshielded twisted pair cabling that is used to trasmit data at 1 Gbps (gigabits per second) with a distance limitation of 220 meters per segment.

AC (alternating current) – An electric current that reverses direction in a circuit at regular intervals. “In the US most household current is AC at 60 cycles per second”

Access Time – The average time interval between a storage peripheral (usually a disk drive or semiconductor memory) receiving a request to read or write a certain location and returning the value read or completing the write.

ACPI (Advanced Configuration and Power Interface) -current power management

AGP (Advanced Graphics Port) – the AGP bus allows the graphics controller to directly access texture map data from the main memory rather than having to move it to the graphic controllers’ local memory first. This helps the system increase the speed of processing graphics and allows for a use of a larger portion of memory by “borrowing” storage for texture maps from main memory.

AMB (advanced memory buffer) – This enables an increase to the width of the memory without increasing the pin count of the memory controller beyond a feasible level. With this architecture, the memory controller does not write to the memory module directly, rather it is done via the AMB. The AMB can thus compensate for signal deterioration by buffering and resending the signal. In addition, the AMB can also offer error correction, without posing any overhead on the processor or the memory controller. It can also use the Bit Lane Failover Correction feature to identify bad data paths and remove them from operation, which dramatically reduces command/address errors. Also, since reads and writes are buffered, they can be done in parallel by the memory controller. This allows simpler interconnects, more memory bandwidth, and (in theory) hardware-agnostic memory controller chips (such as DDR2 and DDR3) which can be used interchangeably. The downside to this approach is that it introduces latency to the memory request. However, the approach should allow higher memory speeds in the future thus obviating this concern.

Ampere -The unit of electrical current flow. One Amp is the current that will flow through a one-ohm resistance when one Volt DC is applied across it

APM (Advanced Power Management) -older and obsolete

AppleTalk – Apple Computer’s network protocol originally designed to run over LocalTalk networks, but can also run on Ethernet and Token Ring.

Areal Density – defined as the product of the linear bits per inch (BPI), measured along the length of the tracks around the disk, multiplied by the number of tracks per inch (TPI), measured radially on the disk.

Array – The area of the RAM that stores the bits. The array consists of rows and columns, with a cell at each intersection that can store a bit.

Asynchronous Memory – Memory that is not synchronized with the system clock. EDO and FPM are examples of asynchronous memory.

ATM (Asynchronous Transfer Mode) – A network protocol that transmits data at a speed of 155 Mbps and higher. It is most often used to interconnect two or more local area networks.

AUI Connector (Attachment Unit Interface) – A 15 pin connector found on Ethernet cards that can be used for attaching coaxial, fiber optic, or twisted pair cable.

Autodetect -Sets up all the parameters on the hard drive

Automatic voltage detection –the system detects and sets the correct voltage by reading certain pins on the processor. Some motherboards do not allow any manual changes to these settings (Asus P5LD2).

Backbone – A cable to which multiple nodes or workstations are attached.

Bandwidth – A measure of the capacity of data that can be moved between two points in a given period of time.

Bank – (1) A slot or group of slots that must be populated with modules of like capacity in order to fulfill the data width requirement of the CPU (2) A segment of memory on a module, sometimes also referred to as a row. Modules are either single or dual banked (3) An internal logic segment in a memory component. For example, a 64Mb SDRAM has 4 banks.

BGA (ball grid array) – A type of memory chip with solder balls on the underside for mounting. Use of BGA allows die package size to be reduced because there is more surface area for attachment. Smaller packaging allows more components to be mounted on a module, making greater densities available. The smaller package also improves heat dissipation for better performance. See CSP and FBGA.

Binary – Numbering system based on two digits: 0 and 1.

bit – Binary digit in the binary numbering system. Its value can be 0 or 1. In an 8-bit character scheme, it takes 8 bits to make a byte (character) of data.

Bit Cell (transition cell) – is a specific area of the medium—controlled by the time and speed at which the medium travels—in which the drive head creates flux reversals.

BNC Connector (Bayone-Neill-Concelman) – Standard connector used to connect 10Base2 coaxial cable.

Bridge – Devices that connect and pass packets between two network segments that use the same communications protocol.

BSB (back-side-bus) – used to connect the CPU to the L2 Cache; is a part of the CPU and has a speed that is dependent on the speed of the processor

BSoD (blue screen of death) – The Blue Screen of Death (sometimes called “bluescreen”, “stop error” or just abbreviated as “BSoD”) is a popular name for the screen displayed by Microsoft’s Windows operating system when it cannot recover from, or is in danger of being unable to recover from, a system error.

Buffered Memory – A buffer isolates the memory from the controller to minimize the load on the chip set. It is typically used when the system has a high density of memory and/or when a system has more than 3 memory module sockets.

Burn-in – The process of exercising an integrated circuit at elevated voltage and temperature. This process accelerates failures normally seen as “infant mortality” in a chip. (Those chips that would fail early during actual usage will fail during burn-in. Those that pass have a life expectancy much greater than that required for normal usage.)

Bus – Circuitry that is used to move data

Byte -A series of 8 bits

Cable – Transmission medium of copper wire or optical fiber wrapped in a protective cover.

Cache Latency (wait state)– The amount of time in nanoseconds (often measured in clock cycles) between a request to read the memory, and when it is actually output.

Client/Server – A networking system in which one or more file servers (Server) provide services; such as network management, application and centralized data storage for workstations (Clients).

Clock Speed – the speed at which a microprocessor executes instruction. The faster the clock, the more instructions the CPU can execute per second.

Controller – One of the major units in a computer that interprets and carries out the instructions in a program.

CSMA/CA – Carrier Sense Multiple Access Collision Avoidance is a network access method in which each device signals its intent to transmit before it actually does so. This prevents other devices from sending information, thus preventing collisions from occurring between signals from two or more devices. This is the access method used by LocalTalk.

CSMA/CD – Carrier Sense Multiple Access Collision Detection is a network access method in which devices that are ready to transmit data first check the channel for a carrier. If no carrier is sensed, a device can transmit. If two devices transmit at once, a collision occurs and each computer backs off and waits a random amount of time before attempting to retransmit. This is the access method used by Ethernet.

Coaxial Cable – Cable consisting of a single copper conductor in the center surrounded by a plastic layer for insulation and a braided metal outer shield.

Concentrator – A device that provides a central connection point for cables from workstations, servers, and peripherals. Most concentrators contain the ability to amplify the electrical signal they receive.

DC (direct current) – an electric current that flows in one direction steadily.

Die – An individual rectangular pattern on a wafer that contains circuitry to perform a specific function. Die are encapsulated to form the black chips that are then placed on a module.

DIN – A plug and socket connector consisting of a circular pattern of pins in a metal sleeve. This type of connector is commonly seen on keyboards.

DMM (Digital Multi-Meters) -probes black for ground and red for back probing

Dumb Terminal – Refers to devices that are designed to communicate exclusively with a host (main frame) computer. It receives all screen layouts from the host computer and sends all keyboard entry to the host. It cannot function without the host computer.

ECC (error correction code) – Logic designed to detect and correct memory errors

EDO (extended data out) – An asynchronous DRAM operating mode that improves access times compared to fast page mode (FPM) DRAMs.

E-mail – An electronic mail message sent from a host computer to a remote computer.

Encoding Method – The particular pattern of flux reversals within the transition cells used to store a given data bit (or bits)

End User – Refers to the human executing applications on the workstation.

endec (encode/decode) – converts the raw binary information to a waveform designed to optimally place the flux transitions (pulses) on the media.

ESD (electrostatic discharge) -The dissipation of electricity. (In layman’s terms, a “shock.”) ESD can easily destroy semiconductor products, even when the discharge is to small to be felt.

Ethernet – A network protocol invented by Xerox Corporation and developed jointly by Xerox, Intel and Digital Equipment Corporation. Ethernet networks use CSMA/CD and run over a variety of cable types at 10 Mbps (megabits per second).

Expansion Slot – Area in a computer that accepts additional input/output boards to increase the capability of the computer.

Extended Memory -anything above 1MB

Fast Ethernet – A new Ethernet standard that supports 100 Mbps using category 5 twisted pair or fiber optic cable.

FC-PGA ( flip chip pin grid array ) -FC-PGA packages use chips that have been turned upside down and attached to the package or the board using solder balls instead of perimeter bonding wires. The solder balls are jointed directly to a set of solder balls on the substrate (the base layer of the chip and the electrical ground for the circuit). The exposed core rests on the actual package, and the chips make direct contact with the heat sink. This allows for more efficient cooling to take place. Since the chips are placed directly on the board, FC-PGA packages have a high I/O density and shorter electrical connections than other types of packaging.

Fiber Distributed Data Interface (FDDI) – A network protocol that is used primarily to interconnect two or more local area networks, often over large distances.

Fiber Optic Cable – A cable, consisting of a center glass core surrounded by layers of plastic, that transmits data using light rather than electricity. It has the ability to carry more information over much longer distances.

File Server – A computer connected to the network that contains primary files/applications and shares them as requested with the other computers on the network. If the file server is dedicated for that purpose only, it is connected to a client/server network. An example of a client/server network is Novell Netware. All the computers connected to a peer-to-peer network are capable of being the file server. Two examples of peer-to-peer networks are LANtastic and Windows for Workgroups.

Firmware –software stored in chips rather than on disk (BIOS contained in ROM chips).

Flux -a magnetic field that has a specific direction or polarity

Flux Reversal (flux transition) -a change in the polarity of the aligned magnetic particles on the surface of the storage medium.

FM (Frequency Modulation)

Gigabit Ethernet – An Ethernet protocol that raises the transmission rates to 1 Gbps (gigabits per second). It is primarily used for a high speed backbone of a network.

Gigabit (Gb) – Amount of memory equal to 1024 Megabits (1,073,741,824 bits) of information

Gigabyte (GB) – One billion bytes of information. One thousand megabytes.

Hit -the corresponding location in the cache is returned.

Hub – A hardware device that contains multiple independent but connected modules of network and internetwork equipment. Hubs can be active (where they repeat signals sent through them) or passive (where they do not repeat but merely split signals sent through them).

IC (integrated circuit) -A tiny complex of electronic components and their connections that is produced in or on a small slice of material (such as silicon).

Infrared – Electromagnetic waves whose frequency range is above that of microwaves, but below that of the visible spectrum.

Intranet – Network internal to an organization that uses Internet protocols.

Internet – A global network of networks used to exchange information using the TCP/IP protocol. It allows for electronic mail and the accessing ad retrieval of information from remote sources.

I/O ports – Connection to a CPU that provides a data path between the CPU and external devices, such as a keyboard, display, or reader. It may provide input only, output only, or both input and output.

Jumper – A jumper in computer electronics is a conductor used to connect two pins.

Keys – Notches on a memory module that help prevent it from being installed incorrectly or into an incompatible system.

LAN (Local Area Network) – A network connecting computers in a relatively small area such as a building.

Lead – The official name for the metal “feet” on an IC. Also called “pins.” The part of the lead assembly that is formed after a portion of the lead frame is cut away. The chip’s connection to the outside world.

Linear Bus – A network topology in which each node attaches directly to a common cable.

LocalTalk – Apple Corporation proprietary protocol that uses CSMA/CA media access scheme and supports transmissions at speeds of 230 Kbps (Kilobits per second).

Logical –addresses are assigned on a column to various devices

MAN (Metropolitan Area Network) – A network connecting computers over a large geographical area, such as a city or school district.

MAU (Multistation Access Unit) – A Token Ring wiring hub.

Memory Configuration – The amount of memory in an IC and how it is accessed

Memory Controller – The logic chip used to handle the I/O (input/output) of data going to and from memory. See Chipset.

MFM -(Modified Frequency Modulation) – All floppy disk drives and some older hard disk drives use the MFM scheme.

MHz (mega)hertz) – A measurement of clock cycles in millions of cycles per second

Miss -if this happens, the data must be retrieved from the main memory address instead of the cache.

Modem (Modulator/Demodulator) – Devices that convert digital and analog signals. Modems allow computer data (digital) to be transmitted over voice-grade telephone lines (analog).

Multiplexer – A device that allows multiple logical signals to be transmitted simultaneously across a single physical channel.

Nanometer (nm) – One billionth of a meter

Nanosecond (ns) – One billionth of a second; used to measure the speed of the parts

Network Modem – A modem connected to a Local Area Network (LAN) that is accessible from any workstation on the network.

Network Interface Card (NIC) – A board that provides network communication capabilities to and from a computer.

Network Operating System (NOS) – Operating system designed to pass information and communicate between more than one computer. Examples include AppleShare, Novell NetWare, and Windows NT Server.

Nibble – Usually 4 bits (half a byte).

Node – End point of a network connection. Nodes include any device attached to a network such as file servers, printers, or workstations.

Node Devices – Any computer or peripheral that is connected to the network.

Nonvolatile Memory – A memory that retains information if power is removed and then reapplied. SRAM and flash are examples of nonvolatile memory

Parity – A bit added to a group of bits to detect the presence of an error. The parity bit looks at the other 8 bits and determines if they are even or odd and correspondingly is a 0 or 1. The system compares the 8 bits with the parity bit. If they both are even or odd, the data is assumed to be correct. If one is even and one is odd, there is an error, and typically the system will fail.

PCMCIA – An expansion slot found in many laptop computers.

Peer-to-Peer Network – A network in which resources and files are shared without a centralized management source.

PGA (pin grid array)

Physical –addresses are all over the place

Physical Topology – The physical layout of the network; how the cables are arranged; and how the computers are connected.

Pin – 1. The metal extensions from an IC package or discrete component that connects the component to the PCB. 2. Another term for the Edge Contacts on a Memory Module

PnP (Plug-n-Play) -Automatically assigns all the resources to your Adapter Cards.

Point-to-Point – A direct link between two objects in a network.

Ports – A connection point for a cable.

Post – Power on self test occurs when the machine turns on before the boot-up. As the name implies it tests all the hardware functions.

Post card –tests the motherboard using hexadecimal routines

Power rating -An amount of power, especially electric power, expressed in watts or kilowatts

Presence Detect – Circuitry on certain memory modules that provides information to the system.

Protocol -A formal description of a set of rules and conventions that govern how devices on a network exchange information.

RAID (Redundant Array of Inexpensive Disks) – A configuration of multiple disks designed to preserve data after a disk casualty.

RAM (Random Access Memory) – The working memory of a computer where data and programs are temporarily stored. RAM only holds information when the computer is on.

Refresh Rate – A count of the number of rows (in thousands) refreshed at a time in a refresh cycle. Common refresh rates are 1K, 2K, 4K, and 8K.

Registered Memory – Registers delay memory information for one clock cycle to ensure all communication from the chipset is collected by the clock edge, providing a controlled delay on heavily loaded memories.

Repeater – A device used in a network to strengthen a signal as it is passed along the network cable.

Reserved Memory -between 640K and 1M reserved for various ROM (384K)

RJ-45 – Standard connectors used for unshielded twisted-pair cable.

RLL (Run Length Limited) – Today’s hard disk drives use one of several
variations on the RLL encoding method

Router -A device that routes information between interconnected networks. It can select the best path to route a message, as well as translate information from one network to another. It is similar to a superintelligent bridge.

SCSI (Small Computer Serial Interface) – An interface controller that allows several peripherals to be connected to the same port on a computer.

SECC (single edge contact cartridge)

Segment – Refers to a section of cable on a network. In Ethernet networks, two types of segments are defined. A populated or trunk segment is a network cable that has one or more nodes attached to it. A link segment is a cable that connects a computer to an interconnecting device, such as a repeater or concentrator, or connects a interconnecting device to another interconnecting device.

SEP (single edge processor)

SEPP (single edge processor package)

SPGA (staggered pin grid array)

SIMD (single instruction, multiple data)

Semiconductor – An element, such as silicon, that is intermediate in electrical conductivity between conductors and insulators, through which conduction takes place by means of holes and electrons.

Sneaker-Net – Refers to a manual method of sharing files in which a file is copied from a computer to a floppy disk, transported to a second computer by a person physically walking (apparently wearing sneakers) to the second computer, and manually transferring the file from floppy disk to the second computer.

Solder – A solder is a fusible metal alloy (often of tin and lead, although lead-based solders were outlawed in many parts of the world in the 1980s), with a melting point or melting range below 450 °C (840 °F) and is melted to join metallic surfaces, especially in the fields of electronics and plumbing, in a process called soldering.

SPD ROM (Serial Presence Detected) -Reports speed and timing parameters to the system. An EEPROM on certain memory modules used to store and provide information to the system using the module.

Speed of Data Transfer – The rate at which information travels through a network, usually measured in megabits per second.

Star Topology – LAN topology in which each node on a network is connected directly to a central network hub or concentrator.

Star-Wired Ring – Network topology that connects network devices (such as computers and printers) in a complete circle.

Superscalar – Refers to microprocessor architectures that enable more than one instruction to be executed per clock cycle

Synchronous Memory – Memory that has its signals synchronized with the system clock. SDRAM and DDR are examples of synchronous memory types.

Tape Back-Up – Copying all the data and programs of a computer system on magnetic tape. On tape, data is stored sequentially. When retrieving data, the tape is searched from the beginning of tape until the data is found.

Terminator – A device that provides electrical resistance at the end of a transmission line. Its function is to absorb signals on the line, thereby keeping them from bouncing back and being received again by the network.

Thicknet – A thick coaxial cable that is used with a 10Base5 Ethernet LAN.

Thinnet – A thin coaxial cable that is used with a 10Base2 Ethernet LAN.

Token – A special packet that contains data and acts as a messenger or carrier between each computer and device on a ring topology. Each computer must wait for the messenger to stop at its node before it can send data over the network.

Token Ring – A network protocol developed by IBM in which computers access the network through token-passing. Usually uses a star-wired ring topology.

Topology – There are two types of topology: physical and logical. The physical topology of a network refers to the configuration of cables, computers, and other peripherals. Logical topology is the method used to pass the information between workstations. Issues involving logical topologies are discussed on the Protocol chapter

Transceiver (Transmitter/Receiver) – A Device that receives and sends signals over a medium. In networks, it is generally used to allow for the connection between two different types of cable connectors, such as AUI and RJ-45.

Tree Topology – LAN topology similar to linear bus topology, except that tree networks can contain branches with multiple nodes.

Twisted Pair – Network cabling that consists of four pairs of wires that are manufactured with the wires twisted to certain specifications. Available in shielded and unshielded versions.

Unbuffered memory – This is where the chip set controller deals directly with the memory. There is nothing between the chip set and the memory chips on the module as they communicate.

Under load– power is connected and turned on, and component is drawing power

USB (Universal Serial Bus) Port – A hardware interface for low-speed peripherals such as the keyboard, mouse, joystick, scanner, printer, and telephony devices.

Voltage -the rate at which energy is drawn from a source that produces a flow of electricity in a circuit; expressed in volts

WAN (Wide Area Network) – A network connecting computers within very large areas, such as states, countries, and the world.

Wattage -An amount of power, especially electric power, expressed in watts or kilowatts

Workgroup – A collection of workstations and servers on a LAN that are designated to communicate and exchange data with one another.

Workstation – A computer connected to a network at which users interact with software stored on the network.

ZIF (zero insertion force)