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A+ Certification
Flash cards for the A+ Certification course
478
Computer Science
Professional
08/25/2006

Additional Computer Science Flashcards

 


 

Cards

Term
ESD
Definition
ElectroStatic Discharge

A great danger to PCs
Term
What kind of environment make ESD worse
Definition
A dry, cool environment
Term
What 4 kinds of PC failures can result from ESD
Definition
1. Upset failures
2. Degradation failures
3. Intermittend failures
4. Catastrophic failures
Term
What is an ESD "upset failute?"
Definition
When an electrical component fails without causing any detectable physical damage.
Term
What is an ESD "Degradation failure?"
Definition
When a component is physically damaged by ESD, but still works.
Term
What is an ESD "Intermittent failure?"
Definition
When a component fails at odd, unpredictable times, but works fine at other times.
Term
What is an ESD "Catastrophic failure?"
Definition
When ESD damage is so severe that the component is physically destroyed and no longer functions.
Term
Name at least two anti-static devices you can use to help prevent ESD.
Definition
1. Anti-static wrist strap
2. Anti-static mats
3. Anti-static bags (for components)
Term
CPU
Definition
Central Processing Unit (also known as the microprocessor)
Term
Who are the two most common makers of CPUs in today's PC industry?
Definition
1. Intel
2. AMD
Term
Clock Speed
Definition
The measure of performance for CPUs. Signifys the number of cycles (calculations) the CPU can perform per second.

Measured in MHz or GHz.

Term
MHz & GHz
Definition

MHz = megahertz (millions of cycles per second)

GHz = Gigahertz (Billions of cycles per second)

Term
CPU "Package"
Definition
Defines how the CPU looks physically and how it connects to the computer.
Term
PGA
Definition
Pin Grid Array - the predominant CPU "Package" used today
Term
SEC (CPU info)
Definition
Single Edge Cartridge - an older type of CPU "Package," no longer used.
Term
RAM
Definition

Random Access Memory

Usually measured in MegaBytes, and each piece is called a "stick"
Term
Byte
Definition
Eight bits is called a Byte, and is represented by a capital 'B' (bits are represented by a small 'b').
Term
DIMM
Definition
Dual Inline Memory Module

184 pin module

Term
SIMM
Definition
Single Inline Memory Module - an older type.
Term
MB, Mb, GB, Gb
Definition
MB = MegaByte = 1 million bytes
Mb = Megabit = 1 million bits
GB = GigaByte = 1024 MegaBytes
Gb = Gigabit = 1024 Megabits
Term
EIDE
Definition
Enhanced Integrated Drive Electronics

A type of hard drive

Term
SCSI
Definition
Small Computer System Interface
Term
Onboard
Definition
Something built into the motherboard
Term
Connectors & Ports
Definition
Connectors are the way that devices plug into the computer, and ports are the receptacles into which the connectors plug.
Term
DB Connectors
Definition
DataBus connectors - have a slight 'D' shape, and have from 9 to 37 pins (male) or sockets (female).

They can be parallel or serial.

Term
[image]
Definition
Male DB15 connector
Term
DIN and MiniDin connectors
Definition
Round connectors, sockets are always female
Term
[image]
Definition
Female 5-pin DIN connector
Term
[image]
Definition
Female 6-pin mini DIN
Term
Centronics connectors
Definition
D-shaped like DB connectors, but larger with one large central tab with contacts instead of pins (but still called n-pin connectors)

Sockets are always female.

Term
[image]
Definition
Centronics 50-pin female socket
Term
RJ connectors
Definition
Look like a telephone plug.
Two types are RJ-11 (phone jack) and RJ-45 (network jack)
Term
[image]
Definition
RJ-45 connector
Term
BNC connectors
Definition
Known as Coaxial or Coax. Consists of a center conductor in an insulation sheath, and then a second conductor as a sheath around the insulation.

Use in PC's is fading.

Term
[image]
Definition
BNC connector
Term
Audio connectors
Definition
The mini-audio connector is used in PCs. Plugs in like earphones.
Term
USB connectors
Definition

Universal Serial Bus connectors.

General purpose and have a rectangular shape. These connectors are hot-swappable, and you can daisy-chain devices
Term
[image]
Definition
USB connector sockets (two types)
Term
Hot-Swappable
Definition
Things that can be connected and disconnected without restarting the computer
Term
Firewire connectors
Definition
Also known as IEEE 1394. Moves data at very high speeds (100 to 400 MBps). Has a 6-wire cable and a unique connector. No single firewire cable can be longer than 5 meters, but you can daisy-chain up to 63 devices off of a single controller.

Hot-swappable and copliant with plug-and-play.

Term
Daisy-chaining
Definition
Running multiple devices off of a single controller.
Term
[image]
Definition
6-wire firewire connector
Term
Video ports
Definition
The video card uses a standard 15-pin female DB connector, or the unique video-only digital video interface (DVI)
Term
DVI
Definition
Digital Video Interface
Term
[image]
Definition
Standard 15-pin female DB video port
Term
[image]
Definition
Dual-link DVI video port
Term
NIC
Definition
Network Interface Card
Term
Serial and Parallel ports
Definition
Serial ports cary data on a single wire, while parallel ports which cary data on multiple wires.
Term
BUS
Definition
Most computers have several buses that transmit data to different parts of the machine. Each bus has a certain size, measured in bits (such as 32-bit or 64-bit), that determines how much data can travel across the bus at one time.

Buses also have a certain speed, measured in megahertz, which determines how fast the data can travel.

Term
Frontside Bus
Definition
Carries data between the CPU and memory. This bus is slower than the CPU - usually half the speed.
Term
Expansion Bus
Definition
Expansion buses, such as PCI and AGP, allow data to move to and from expansion cards, including video cards and other I/O devices.
Term
EDB
Definition

External Data Bus

A bus that connects a computer to peripheral devices
Term
Backside Bus
Definition
Carries data between the CPU and the L2 (secondary) cache.
Term
Internal Data Bus
Definition
A bus that operates only within the internal circuitry of the CPU, communicating among the internal caches of memory that are part of the CPU chip’s design.

This bus is typically rather quick and is independent of the rest of the computer’s operations.

Term
Register
Definition
A, special, high-speed storage area within the CPU. All data must be represented in a register before it can be processed.

The number of registers that a CPU has and the size of each (number of bits) help determine the power and speed of a CPU. For example a 32-bit CPU is one in which each register is 32 bits wide. Therefore, each CPU instruction can manipulate 32 bits of data.

Term
Instruction Set
Definition
Also called a command set, the basic set of commands, or instructions, that a microprocessor understands.
Term
Clock speed
Definition
Also called clock rate, the speed at which a microprocessor executes instructions.

Every computer contains an internal clock that regulates the rate at which instructions are executed and synchronizes all the various computer components.

The CPU requires a fixed number of clock ticks (or clock cycles) to execute each instruction. The faster the clock, the more instructions the CPU can execute per second.

Term
Hertz
Definition
A measure of clock cycles per second. One Hertz (1 Hz) is one cycle per second.
Term
MHz
Definition
MegaHertz - one MHz is a million cycles per second.
Term
GHz
Definition
GigaHertz - one GHz is a billion cycles per secone.
Term
Underclocking
Definition
Running a CPU slower than it rated speed.
Term
Overclocking
Definition
Running a CPU faster than its rated speed.
Term
RAM
Definition
Random Access Memory.

a type of computer memory that can be accessed randomly; that is, any byte of memory can be accessed without touching the preceding bytes.

Term
Bit
Definition
A single binary 1 or zero.

Short for binary digit, the smallest unit of information on a machine.

Term
Nibble
Definition
4 bits
Term
Byte
Definition
8 bits

Abbreviation for binary term, a unit of storage capable of holding a single character. On almost all modern computers, a byte is equal to 8 bits.

Term
Word
Definition
16 bits (2 bytes)

the natural data size of a computer. The size of a word varies from one computer to another, depending on the CPU. For computers with a 16-bit CPU, a word is 16 bits (2 bytes). On large mainframes, a word can be as long as 64 bits (8 bytes).

Term
Double Word
Definition
32 bits
Term
Paragraph
Definition
64 bits - also called a quad word
Term
Address Bus
Definition
A collection of wires connecting the CPU with main memory that is used to identify particular locations (addresses) in main memory.

The width of the address bus (that is, the number of wires) determines how many unique memory locations can be addressed.

Modern PCs and Macintoshes have as many as 36 address lines, which enables them theoretically to access 64 GB (gigabytes) of main memory. However, the actually amount of memory that can be accessed is usually much less than this theoretical limit due to chipset and motherboard limitations.

Term
Northbridge
Definition
Sits between the CPU and RAM

Northbridge is the chip or chips that connect a CPU to memory, the PCI bus, Level 2 cache and AGP activities.

The Northbridge can consist of more than one discrete chip.

Term
Southbridge
Definition
Sits between the Northbridge and the rest of the Motherboard.

the Southbridge is the chip that controls all of the computers I/O functions, such as USB, audio, serial, the system BIOS, the ISA bus, the interrupt controller and the IDE channels.

the Southbridge is typically only one discrete chip that rests on the Northbridge’s PCI bus.

Term
KB
Definition
KiloByte = 1,024 Bytes (2 to the 10th power)
Term
MB
Definition
MegaByte = 2 to the 20th power = 1,048,576 Bytes
Term
GB
Definition
GigaByte = 2 to the 30th power
Term
TB
Definition
TeraByte = 2 raised to the 40th power
Term
CPU "Package"
Definition
The shape of the CPU, and how it connects to the motherboard.
Term
PGA
Definition
Pin Grid Array = A CPU package that is square in shape, and connects with many (100's) of tiny pins.
Term
PGA variations (3) based on material used.
Definition
CPGA = Ceramic PGA
PPGA = Plastic PGA
FC-PGA = Flip-Chip PGA (CPU is soldered onto a small board).
Term
ZIF
Definition
Zero-Insertion-Force CPU socket.

Square in shape and has a removal arm.

Term
Early Pentium CPUs
Specifications
Definition
  • 5th Generation CPU
  • External Speed Range = 50-66 MHz
  • Internal Speed Range = 60-200 MHz
  • Mulitplier range = x1-x3
  • L1 cache? Yes, 16KB
  • L2 cache? No
  • L3 cache? No
  • Package = PGA
  • Sockets = 4 & 5
Term
Early AMD/Cryix Pentium Equivalents
Specifications
Definition
  • 5th Generation CPU
  • External Speed Range = 50-75 MHz
  • Internal Speed Range = 60-150 MHz
  • Mulitplier range = x1.5-x2
  • L1 cache? Yes, 16KB
  • L2 cache? No
  • L3 cache? No
  • Package = PGA
  • Sockets = 7
Term
Intel Pentium Pro
Specifications
Definition
  • 6th Generation CPU
  • External Speed Range = 60-66 MHz
  • Internal Speed Range = 166-200 MHz
  • Mulitplier range = x2.5-x3
  • L1 cache? Yes, 16KB
  • L2 cache? Yes, 256KB, 512KB, and 1MB
  • L3 cache? No
  • Package = PGA
  • Sockets = 8
Term
Later Pentium CPUs
Specifications
Definition
  • 5th Generation CPU
  • External Speed Range = 66-75 MHz
  • Internal Speed Range = 166-200 MHz
  • Mulitplier range = x2.5-x4.5
  • L1 cache? Yes, 32KB
  • L2 cache? No
  • L3 cache? No
  • Package = PGA
  • Sockets = 7
Term
Intel Pentuim II CPUs
Specifications
Definition
  • 6th Generation CPU
  • External Speed Range = 66-100 MHz
  • Internal Speed Range = 233-450 MHz
  • Mulitplier range = x3.5-x4.5
  • L1 cache? Yes, 32KB
  • L2 cache? Yes, 512KB
  • L3 cache? No
  • Package = SEC
  • Sockets = Slot 1
Term
AMD K6-Family CPUs
Specifications
Definition
6th Generation CPU
External Speed Range = 66-100 MHz
Internal Speed Range = 200-550 MHz
Mulitplier range = x3-x5.5
L1 cache? Yes, 32KB (K6 & K6-2),64KB (K6-III)
L2 cache? Yes, 256KB (on K6-III
L3 cache? No
Package = PGA
Sockets = 7
Term
Pentium II-Based Celeron CPUs
Specifications
Definition
6th Generation CPU
External Speed Range = 66 MHz
Internal Speed Range = 266-700 MHz
Mulitplier range = x4-x10.5
L1 cache? Yes, 32KB
L2 cache? Yes, 128KB (Later versions only)
L3 cache? No
Package = SEP & PGA
Sockets = Slot 1, Socket 370
Term
Intel Pentium III CPUs
Specifications
Definition
  • 6th Generation CPU
  • External Speed Range = 100-133 MHz
  • Internal Speed Range = 450 MHz-1.26 GHz
  • Mulitplier range = x4-x10
  • L1 cache? Yes, 32KB
  • L2 cache? Yes, 256KB or 512KB
  • L3 cache? No
  • Package = SEC-2, PGA
  • Sockets = Slot 1, Socket 370
Term
Intel Pentium III-Based Celeron CPUs
Specifications
Definition
  • 6th Generation CPU
  • External Speed Range = 66-100 MHz
  • Internal Speed Range = 533-700 MHz
  • Mulitplier range = x8-x11.5
  • L1 cache? Yes, 32KB
  • L2 cache? Yes, 128KB
  • L3 cache? No
  • Package = PGA
  • Sockets = 370
Term
Classic AMD Athlon CPUs
Specifications
Definition
  • 6th Generation CPU
  • External Speed Range = 100 MHz (Doubled)
  • Internal Speed Range = 500 Mhz-1 GHz
  • Mulitplier range = x5-x10
  • L1 cache? Yes, 128KB
  • L2 cache? Yes, 512KB
  • L3 cache? No
  • Package = SEC
  • Sockets = Slot A
Term
AMD Thunderbird Athlon CPUs
Specifications
Definition
  • 6th Generation CPU
  • External Speed Range = 100-133 MHz
  • Internal Speed Range = 650 MHz-1.4 GHz
  • Mulitplier range = x3.5-x14
  • L1 cache? Yes, 128KB
  • L2 cache? Yes, 256KB
  • L3 cache? No
  • Package = PGA
  • Sockets = A
Term
AMD Duron CPUs
Specifications
Definition
  • 6th Generation CPU
  • External Speed Range = 100 MHz
  • Internal Speed Range = 600 Mhz-1.3 GHz
  • Mulitplier range = x3.5-x14
  • L1 cache? Yes, 128KB
  • L2 cache? Yes, 64KB
  • L3 cache? No
  • Package = PGA
  • Sockets = A
Term
Intel Pentium 4 CPUs
Specifications
Definition
  • 7th Generation CPU
  • External Speed Range = 100-133-200 MHz (Quad speed)
  • Internal Speed Range = 1.3-3.2 GHz
  • Mulitplier range = x13-x23
  • L1 cache? Yes, 128KB
  • L2 cache? Yes, 256KB or 512KB
  • L3 cache? No
  • Package = 423-pin PGA, 478-pin PGA
  • Sockets = 423, 478
Term
AMD Athlon XP CPUs
Specifications
Definition
  • 7th Generation CPU
  • External Speed Range = 133-166 MHz (Dual speed)
  • Internal Speed Range = 1.3-2.16 GHz
  • Mulitplier range = x13-x16.5
  • L1 cache? Yes, 128KB
  • L2 cache? Yes, 256KB or 512KB
  • L3 cache? No
  • Package = 462-pin PGA
  • Sockets = A
Term
Intel Pentium II-Based Xeon CPUs
Specifications
Definition
  • 6th Generation CPU
  • External Speed Range = 100 MHz
  • Internal Speed Range = 400-450 MHz
  • Mulitplier range = x4-x4.5
  • L1 cache? Yes, 32KB
  • L2 cache? Yes, 512KB - 2MB
  • L3 cache? No
  • Package = SEC
  • Sockets = Slot 2
Term
Intel Pentium III-Based Xeon CPUs
Specifications
Definition
  • 6th Generation CPU
  • External Speed Range = 100-133 MHz
  • Internal Speed Range = 500 MHz-1 GHz
  • Mulitplier range = x5-x7.5
  • L1 cache? Yes, 32KB
  • L2 cache? Yes, 256KB, 512KB, 1MB, 2MB
  • L3 cache? No
  • Package = SEC
  • Sockets = Slot 2
Term
Intel Pentium 4-Based Xeon CPUs
Specifications
Definition
  • 7th Generation CPU
  • External Speed Range = 100-133 MHz
  • (Quad speed)
  • Internal Speed Range = 1.4-3.06 GHz
  • Mulitplier range = x14-x28
  • L1 cache? Yes, 12KB
  • L2 cache? Yes, 256KB, 512KB
  • L3 cache? No
  • Package = PGA
  • Sockets = 603
Term
Intel Pentium 4-Based Xeon MP CPUs
Specifications
Definition
  • 7th Generation CPU
  • External Speed Range = 100-133 MHz (Quad speed)
  • Internal Speed Range = 1.4-2 GHz
  • Mulitplier range = x14-x20
  • L1 cache? Yes, 12KB
  • L2 cache? Yes, 256KB, 512KB
  • L3 cache? Yes, 512KB, 1MB, 2MB
  • Package = PGA
  • Sockets = 603
Term
Intel Itanium CPUs
Specifications
Definition
  • 8th Generation CPU
  • Physical Address = 44 bits
  • Frontside Bus Width = 64 bit
  • External Speed Range = 133 MHz (Quad speed)
  • Internal Speed Range = 733-833 MHz
  • Mulitplier range = x6-x8.5
  • L1 cache? Yes, 32KB
  • L2 cache? Yes, 96KB
  • L3 cache? Yes, 2MB, 4MB
  • Package = PAC
  • Sockets = 418
Term
Intel Itanium II CPUs
Specifications
Definition
  • 8th Generation CPU
  • Physical Address = 50 bits
  • Frontside Bus Width = 128 bits
  • External Speed Range = 100 MHz (Quad speed)
  • Internal Speed Range = 900 MHz, 1GHz
  • Mulitplier range = x9-x10
  • L1 cache? Yes, 32KB
  • L2 cache? Yes, 256KB
  • L3 cache? Yes, 1.5MB, 3MB
  • Package = OLGA
  • Sockets = 611
Term
AMD Opteron CPUs
Specifications
Definition
  • 8th Generation CPU
  • Physical Address = 40 bits
  • Frontside Bus Width = 128 bit
  • External Speed Range = 6.4 GHz (Hypertransport)
  • Internal Speed Range = 1.4-1.8 GHz
  • Mulitplier range = x14-x20
  • L1 cache? Yes, 128KB
  • L2 cache? Yes, 1MB
  • L3 cache? No
  • Package = Micro-PGA
  • Sockets = 940
Term
CPU Socket 4
Definition
  • Number of Pins 273
  • Pin Rows 4
  • Voltage 5 volts
  • Motherboard 1st Generation Pentium
  • Supported Processors Pentium 60-66 MHz, Pentium OverDrive
Term
CPU Socket 5
Definition
Socket 5 was created for the second generation of Intel Pentium processors operating at speeds from 75 to 133 MHz as well as certain Pentium OverDrive processors.

Pentium MMX processors are not compatible with Socket 5. Consisting of 320 pins, this was the first socket to use a staggered pin grid array, or SPGA. This design allowed the chip's pins to be spaced closer together.

Term
CPU Socket 7
Definition
  • Type: ZIF
  • Contacts: 321
  • FSB : 66 - 83 Mhz System Clock
  • Voltage range : 2.5V - 3.5V
  • Processors: 75-233 MHz Intel
  • Pentium, AMD K5 through K6, Cyrix 6x86 (and MX) P120 - P233
Term
CPU Socket 370
Definition
  • Type PGA-ZIF
  • Chip form factors Plastic pin grid array (PPGA) and Flip-chip pin grid array (FC-PGA and FC-PGA2)
  • Contacts 370
  • Bus Protocol GTL+
  • FSB 66, 100 and 133 MHz
  • Voltage range 1.05–2.1 V
  • Processors Intel Celeron (PPGA, 300–533 MHz) Intel Celeron (FC-PGA, 533–1100 MHz) Intel Celeron (FC-PGA2, 900–1400 MHz) Intel Pentium III (FC-PGA, 500–1133 MHz) Intel Pentium III (FC-PGA2, 1000–1400 MHz) VIA Cyrix3/C3 (500–1200 MHz)
Term
CPU Socket 478
Definition
  • Type PGA-ZIF
  • Chip form factors Flip-chip pin grid array (FC-PGA2)
  • Contacts 478
  • Bus Protocol AGTL+
  • FSB 400 MT/s 533 MT/s 800 MT/s
  • Voltage range
  • Processors Intel Pentium 4 (1.4 - 3.4 GHz) Intel Celeron (1.7 - 3.2 GHz) Celeron D (to 3.2 GHz) Intel Pentium 4 Extreme Edition (3.2, 3.4 GHz)
Term
CPU Socket A
Definition
  • Type PGA-ZIF
  • Chip form factors Ceramic Pin Grid Array (CPGA) Organic Pin Grid Array (OPGA)
  • Contacts 453
  • Bus Protocol EV6
  • FSB 100 MHz, 133 MHz, 166 MHz and 200 MHz equivalent to FSB200, FSB266, FSB333 and FSB400 (Double data rate Bus)
  • Voltage range 1.1 - 2.05 V
  • Processors AMD Athlon (650 MHz - 1400 MHz) AMD Athlon XP (1500+ - 3300+) AMD Duron (600 MHz - 1800 MHz) AMD Sempron (2000+ - 3300+) AMD Athlon MP (1000 MHz - 3000+)
Term
CPU Slot 1
Definition
Slot 1

Specifications
Type Slot
Chip form factors Single Edge Connector Cartridge (Pentium II)
Single Edge Connector Cartridge 2 (Pentium III)
Single Edge Processor Package (Celeron)
Contacts 242
Bus Protocol GTL+
FSB 66, 100, and 133 MHz
Voltage range 1.65 to 2.80 V
Processors Intel Pentium II (SECC, 233-450 MHz)
Intel Pentium III (SECC2, 450-1133 MHz)
Intel Celeron (SECC, 233-466 MHz)
Term
CPU Slot A
Definition
Slot A refers to the physical and electrical specification for the edge-connector used by early versions of AMD's Athlon processor.

The connector allows for a higher bus rate than Socket 7 or Super Socket 7. Slot A motherboards use DEC's EV6 bus protocol, technology that was originally developed for the Alpha processor. Slot A is mechanically compatible but electrically incompatible with Intel's Slot 1. It was superseded by Socket A.
Term
CPU Socket 8
Definition
Type: LIF-ZIF
Contacts: 387
Bus Speed : 66-75 MHz
Voltage range : 2.1 - 3.5 V
Processors: Pentium Pro 150~200, Pentium II OverDrive 300~333, Evergreen AcceleraPCI, PowerLeap PL-Pro/II, PowerLeap PL-Renaissance/AT, PowerLeap PL-Renaissance/PCI
Term
Super Socket 7
Definition
The Super Socket 7, also referred to as Super 7, is an extension of the Socket 7 ZIF socket specification. It features a 100 MHz front-side bus, support for the AGP bus, and an SPGA package.

Super Socket was used by AMD K6-2 and K6-III processors, and some of the final Cyrix M-II processors. It is backward compatible with Socket 7, meaning a Socket 7 CPU can be used with a Super Socket 7 motherboard, but a Super Socket 7 CPU cannot operate at full speed in a Socket 7 motherboard.

Socket 5 CPUs are pin-compatible with Super Socket 7, but no motherboard designed for Super Socket 7 ever supported the voltages needed for Socket 5 CPUs.

While AMD had previously always used Intel sockets for their processors, Socket 7 was the last one for which AMD retained legal rights. Intel had hoped by discontinuing Socket 7 development and moving to Slot 1 that AMD would be left with an outdated platform, making their processors non-competitive. By extending the FSB from 66 to 100 MHz, Super Socket 7 gave AMD the stopgap solution they needed while developing their own independent motherboard infrastructure, Slot A.

While the architecture was cheap, and served the intended purpose, many of the third party chipsets provided by VIA, SiS, and others, were of low quality, especially in regard to the AGP implementations. The reputation AMD gained for buggy incompatible motherboards lingered, and subsequently AMD put in place a quality assurance program for the Athlon processor.

Term
SEC
Definition
Single-Edge Contact
A CPU slot
Term
Multiprocessing
Definition
Multiprocessing is a generic term for the use of two or more central processing units (CPUs) within a single computer system
Term
Cache
Definition
In computer science, a cache is a collection of data duplicating original values stored elsewhere or computed earlier, where the original data is expensive (usually in terms of access time) to fetch or compute relative to reading the cache.

Once the data is stored in the cache, future use can be made by accessing the cached copy rather than refetching or recomputing the original data, so that the average access time is lower.

Term
Disk Cache
Definition
The disk buffer (cache) is controlled by the embedded computer in the disk drive. The disk buffer is usually quite small, 2 to 16 MB, and the page cache is generally all unused physical memory, which in a 2006 PC may be as much as 2GB.
Term
RAM Cache
Definition
Another Term to describe L2 Cache
Term
L2 Cache
Definition
Short for Level 2 caching, L2 is also commonly referred to as secondary cache or external cache. Unlike Layer 1 cache, L2 cache is commonly located on the motherboard, although with most new processors it is being found on the processor.

When L2 cache is found on the processor, if cache is found on the motherboard, it is properly known as L3 cache.

First introduced with the Intel Pentium and Pentium Pro computers. In some cases this required that the user install or have installed optional L2 cache for L2 support.

L2 Cache on computers can range from 64KB to 2MB in size. However, early versions of the Intel Celeron had no L2 cache.

Term
L1 Cache
Definition
Also known as L1 cache, primary cache, or internal cache.

When referring to computer processors, L1 cache is cache built on to the processor and is commonly the fastest cache in the computer.

Term
L3 Cache
Definition
Type of cache that is found on the motherboard instead of the processor. Cache on the processor is known as L2 cache.
Term
DRAM
Definition
Short for Dynamic Random Access Memory, DRAM is one of the most commonly found memory modules in PC compatible personal computers and workstations.

DRAM stores its information in a cell containing a capacitor and transistor; because of this design, these cells must be refreshed with new electricity every few milliseconds allowing the memory to keep its charge and hold the data as long as needed.

When using this type of memory, if the computer is powered off, the information within memory will be lost.

Term
Capacitor
Definition
Component that stores an electrical charge and discharges it uniformly. Used for storage in DRAM.
Term
DRAM Refresh
Definition
When referring to computer memory, refresh refers to the recharging of dynamic RAM (DRAM) chips that allows those chips to keep the data they are storing available.

Memory refresh-rate is commonly displayed as xK, where x is a number such as 2 or 4. If the memory has a refresh-rate of 2k, this indicates how many rows it takes to complete the refresh.

In our example of 2k, this indicates there are 2 thousand rows. The refresh cycle indicates the time it requires to complete one row.

Term
Volatile Memory
Definition
Type of memory whose contents are erased when the system's power is turned off (or interrupted).

RAM is volatile, but ROM is not. It is because of RAM's volatile nature that users must frequently save their work to a permanent medium, such as a hard drive, to avoid losing data if the system's power is interrupted.

Term
Wait State
Definition
A pause in the processor's clock cycles that allows the processor to halt while it waits for data from other components, such as memory.

Wait states occur frequently when the computer's processor has a higher clock speed than other components in the computer.

One common wait state is unnoticeable; however, several can affect the overall performance of a computer.

Term
SRAM
Definition
Short for Static RAM, SRAM is a type of computer memory that requires a constant power flow in order to hold information.

Although quicker than DRAM, SRAM is much more expensive and requires more power; therefore, it is commonly only used in cacheive video card memory.

Term
Flip-Flop
Definition
In electronics and digital circuits, the flip-flop or bistable multivibrator is a pulsed digital circuit capable of serving as a one-bit memory.

A flip-flop typically includes zero, one, or two input signals; a clock signal; and an output signal, though many commercial flip-flops additionally provide the complement of the output signal. Some flip-flops include a clear input signal, which resets the current output.

Because flip-flops are implemented as integrated circuit chips, they also require power and ground connections.

Term
Internal Cache
Definition
L1 cache
Term
Primary Cache
Definition
L1 cache
Term
External cache
Definition
L2 or L3 cache
Term
Secondayr Cache
Definition
L2 or L3 cache
Term
Branch Predictions
Definition
In computer architecture, a branch predictor is the part of a processor that determines whether a conditional branch in the instruction flow of a program is likely to be taken or not. This is called branch prediction.

Branch predictors are crucial in today's modern, superscalar processors for achieving high performance. They allow processors to fetch and execute instructions without waiting for a branch to be resolved.

Almost all pipelined processors do branch prediction of some form, because they must guess the address of the next instruction to fetch before the current instruction has been executed. Many earlier microprogrammed CPUs did not do branch prediction because there was little or no performance penalty for altering the flow of the instruction stream. Branch prediction is not the same as branch target prediction. Branch prediction attempts to guess whether a conditional branch will be taken or not. Branch target prediction attempts to guess the target of the branch or unconditional jump before it is computed from parsing the instruction itself.
Term
Pipelining
Definition
In computing, a pipeline is a set of data processing elements connected in series, so that the output of one element is the input of the next one.

The elements of a pipeline are often executed in parallel or in time-sliced fashion; in that case, some amount of buffer storage is often inserted between elements.

Computer-related pipelines include:
Instruction pipelines, such as the classic RISC pipeline, which are used in processors to allow the parallel execution of two or more consecutive instructions from a nominally sequential stream; the processing elements are the logical circuits that implement the various stages of an instruction (address decoding and arithmetic, register fetching, cache lookup, etc.).

Term
Clock Multiplying
Definition
The CPU multiplier is one way for processors to run much faster than the clock speed that the motherboard or RAM allows

For every tick of the front side bus (FSB) clock, a frequency multiplier causes the CPU to perform x cycles, where x is the multiplier.

So, for example, if the FSB has a clock speed of 133 MHz and the CPU multiplier is 10x, then the processor would run at 1.33GHz. This means a processor can be run much much faster without having to increase RAM speeds or motherboard speeds and worry about desyncs, or other speed related issues.<.p>

Term
CPUID
Definition
The CPUID opcode (derived from CPU IDentification) is part of the x86 architecture and invented by Intel in 1993 at the introduction of the Pentium processor.

By using the CPUID opcode, software can determine processor type and the presence of features (like MMX/SSE).

The CPUID opcode is 0FA2h and the value in the EAX register specifies what information to return.

Term
Motherboard Voltage
Definition
The advent of processors and other devices running at different voltages--in the "old days" they all used to run at the 5V provided by a standard power supply--has led to the necessity of one or more voltage regulators on most modern motherboards.

These regulators reduce the 5V signal to those voltages typically needed by processors: 3.3V or lower.

Term
VRM
Definition
A voltage regulator module or VRM is an electronic device that provides a microprocessor the appropriate supply voltage.

It can be soldered to the motherboard or be an installable device. It allows processors with different supply voltage to be mounted on the same motherboard.

Some voltage regulators provide a fixed supply voltage to the processor, but most of them sense the required supply voltage from the processor. In particular, VRMs that are soldered to the motherboard are supposed to do the sensing, according to the Intel specification.

The correct supply voltage is communicated by the microprocessor to the VRM at startup via a number of bits called VID (voltage identificator). In particular, the VRM initially provides a standard supply voltage to the VID logic, which is the part of the processor whose only aim is to then send the VID to the VRM.

When the VRM has received the VID identifying the required supply voltage, it starts acting as a voltage regulator, providing the required constant voltage supply to the processor.

Term
P6
Definition
The Pentium Pro
The P6 microarchitecture is the sixth generation x86 microprocessor architecture of Intel, released in 1995. It was succeeded by the NetBurst microarchitecture in 2000, but eventually revived in the Pentium M line of microprocessors.
Term
Three improvements in the Pentium Pro (over the Pentium)
Definition
  • 1. Quad pipelining
  • 2. Dynamic processing
  • <3. On-chip L2 cache
Term
Dynamic Processing
Definition
The ability of the CPU to look ahead at the code in the pipeline during a wait state, and execute the code out of order, rearranging commands back into order when DRAM returned the code.
Term
MMX
Definition
Multi-Media eXtensions
MMX is a SIMD instruction set designed by Intel, introduced in 1997 in their Pentium MMX microprocessors. It developed out of a similar unit first introduced on the Intel i860. It has been supported on most subsequent IA-32 processors by Intel and other vendors.
Term
EEPROM
Definition

Electrically Erasable Programmable Read-Only Memory.

A type of ROM chip that can be erased and reprogrammed electrically. EEPROMs were the most common storage device for BIOS before the advent of Flash ROM.
Term
Flash ROM
Definition

A type of ROM technology which can be electrically reprogrammed while still in the PC.

Flash is the overwhelmingly most common storage medium of BIOS in PCs today, as it can be upgraded without even having to open the computer on most systems.
Term
Real Mode
Definition
The original 64K segmented memory, single-tasking operating mode of
the Intel 8086 and 8088 CPUs.
Term
Protected Mode
Definition
The operating mode of a CPU allowing more than one program to be run while ensuring that no program can corrupt another program currently running.
Term
Memory
Definition

A device or medium for temporary storage of programs and data during program execution.

The term is synonymous with storage, although it is most frequently used for referring to the internal storage of a computer that can be directly addressed by operating instructions.

A computer’s temporary storage capacity is measured in kilobytes (KB) or megabytes (MB) of RAM (random-access memory).

Long-term data storage on disks is also measured in kilobytes, megabytes, gigabytes, and terabytes.

Term
MMU
Definition

Memory-Management Unit

A chip or circuit that translates virtual memory addresses into physical addresses and may implement memory protection.
Term
UMA
Definition

Upper Memory Area

The memory area between the first 640K and 1024K reserved for system use and device drivers.
Term
UMB
Definition

Upper Memory Block

The open areas of the Reserved Memory (the 384K block above Conventional Memory) loading Adapter ROM and device drivers.
Term
Conventional Memory
Definition

In any IBM PC-compatible computer, the first 640K of the computer’s RAM.

This amount proved to be insufficient because of programs that demanded more memory and users who wanted to run more than one program at a time. Many DOS users equipped their systems with extended or expanded memory and the memory management programs needed to access that memory.

Term
XMS
Definition

Extended Memory Services

The RAM above 1MB that is installed directly on the motherboard, and is directly accessible to the microprocessor. Usually shortened to simply “extended memory.”
Term
EMS
Definition

Expanded Memory Specification

A method of memory management developed by Intel, Lotus, and Microsoft that enabled MS-DOS computers to use memory exceeding the 640K limit imposed by MS-DOS.

Memory that conforms to this standard is called expanded memory. Originally, this standard required that a special hardware device be added to the computer, but that was quickly supplanted by a less efficient but much cheaper software solution.

Expanded memory has been made almost obsolete by the Windows environment, which isn’t limited by the 640K barrier. EMS is now required almost solely by DOS-based games.

Term
Virtual Memory
Definition

Pertaining to a device or facility that does not physically exist, yet behaves as if it does.

For example, a system with 4MB of virtual memory may have only 1MB of physical memory plus additional (slower and cheaper) auxiliary memory. Yet programs written as if 4MB of physical memory were available will run correctly.

Term
TSR
Definition

Terminate and Stay Resident

A DOS program that closes immediately after starting up, but leaves a tiny piece of itself in memory.

TSRs are used to handle a broad cross-section of DOS-level system needs, such as running hardware (MOUSE.COM) or applying higher-level functionality to hardware already under the control of device drivers.

MSCDEX.EXE, for example, assigns a drive letter to a CD-ROM drive after the CD-ROM driver has loaded in CONFIG.SYS.

Term
CHS
Definition

Cylinders, Heads, and Sectors per Track

The initials for the combination of the three critical geometries used to determine the size of a hard drive—cylinders, heads, and sectors per track.

Term
Boot Sector
Definition

The first sector on an IBM-PC hard drive or floppy disk, track 0.

The boot-up software in ROM tells the computer to load whatever program is found there. If a system disk is read, the program in the boot record directs the computer to the root directory to load the operating system.

Term
Sector
Definition

A segment of one of the concentric tracks encoded on the disk during a lowlevel format.

Sectors hold 512 bytes of data.

Term
Cluster
Definition

The basic unit of storage on a floppy or hard disk.

Two or more sectors are contained in a cluster. When DOS/Windows 9x stores a file on disk, it writes those files into dozens or even hundreds of contiguous clusters.

If there aren’t enough contiguous open clusters available, the operating system finds the next open cluster and writes there, continuing this process until the entire file is saved.

The FAT tracks how the files are distributed among the clusters on the disk.

Term
10Base2
Definition

Also called Thinnet or Thin Ethernet

An Ethernet LAN designed to run on common coax RG-58 cabling, almost exactly like the coax for cable television.

It runs at 10 megabits per second and has a maximum segment length of 185 meters. It uses baseband signaling and BNC connectors.

No industry standard spelling exists, so sometimes written 10BASE-2 or 10Base2.

Term
Thinnet ot Thin Ethernet
Definition
10Base2
Term
10Base5
Definition

Also called Thicknet or Thick Ethernet

The original Ethernet LAN, designed to run on specialized coax cabling. It runs at 10 megabits per second and has a maximum segment length of 500 meters.

10Base5 uses baseband signaling. It uses DIX or AUI connectors and external transceivers.

No industry standard spelling exists, so sometimes written 10BASE-5 or 10Base5.

Term
Thicknet or Thick Enhernet
Definition
10-Base5
Term
10BaseT
Definition
An Ethernet LAN designed to run on UTP cabling. 10BaseT runs at 10 megabits per second.

The maximum length for the cabling between the NIC and the hub (or switch, repeater, etc.) is 100 meters. It uses baseband signaling.

No industry standard spelling exists, so sometimes written 10BASE-T or 10BaseT.

Term
100BaseFX
Definition

Fiberoptic implementation of Ethernet that runs at 100 megabits per second.

It uses baseband signaling. Maximum length of the cable is 400 meters.

No industry standard spelling exists, so sometimes written 100BASE-FX or 100BaseFX.

Term
100BaseT
Definition

A generic term for any Ethernet cabling system that is designed to run at 100 megabits per second on UTP cabling.

It uses baseband signaling. No industry standard spelling exists, so sometimes written 100BASE-T or 100BaseT.

Term
100BaseT4
Definition

An Ethernet LAN designed to run on UTP cabling.

It runs at 100 megabits per second and uses four pairs of wires on CAT3 or better cabling. No industry standard spelling exists, so sometimes written 100BASE-T4 or 100BaseT4.

Term
5-4-3 Rule
Definition
A rule for approximating the correct size of a collision domain. In a collision domain, no two nodes may be separated by more than five repeaters, four segments, and three populated segments.
Term
80286
Definition
Intel’s second-generation processor. The 286 has a 16-bit external data bus and a 24-bit address bus. It was the first Intel processor to achieve 286 protected mode.
Term
80386DX
Definition
Intel’s third generation processor. The 386DX has a 32-bit external data bus and 32-bit address bus. It was Intel’s first true 32-bit processor
and could run in both 286 protected mode and 386 protected mode.
Term
80386SX
Definition
A hybrid chip that combined the 32-bit functions and modes of the 80386DX with the 16-bit external data bus and 24-bit address bus of the 80286.
Term
486DX
Definition
Intel’s fourth-generation CPU. Essentially an 80386DX with a built-in cache and math coprocessor.
Term
486DX/2, 486DX/3, 486DX/4
Definition

486 CPUs that operate externally at one speed and internally at a speed which is two, three, or four times faster.

Although the internal speed can be more than two times as fast as the external speed, these CPUs are known collectively as “clock doublers.”

Term
486SX
Definition
A 486DX without the built-in math coprocessor.
Term
586
Definition
An unofficial, generic term that describes the Intel Pentium processor or Pentium family of CPUs.
Term
686
Definition
An unofficial, generic term that describes the Intel Pentium II processor or equivalent
CPUs.
Term
8086/8088
Definition
The first generation of Intel processor used in IBM PCs. The 8086 and
8088 were identical with the exception of the external data bus—the 8086 had a
16-bit bus while the 8088 had an 8-bit bus.
Term
8086 Mode
Definition
Same a Real Mode
Term
8237
Definition
The part number for the original DMA controller. Although long obsolete, the
name is still often used in reference to DMA.
Term
8259
Definition
The part number for the original IRQ controller. Although long obsolete, the
name is still often used in reference to IRQ usage.
Term
Access Time
Definition
The time interval measured from the moment that data is requested to
the moment it is received. Most commonly used in measuring the speed of storage devices.
Term
ACPI
Definition

Advanced Configuration and Power Interface

A power management specification that far surpasses its predecessor, APM, by providing support for hot swappable devices and better control of power modes.

Term
Active Directory
Definition
A form of directory service used in networks with Windows 2000 Servers.
Term
Address Bus
Definition

The wires leading from the CPU to the memory controller chip (chipset) that enable the CPU to address RAM.

Also used by the CPU for I/O addressing. An internal electronic channel from the microprocessor to random-access memory, along which the addresses of memory storage locations are transmitted.

Like a post office box, each memory location has a distinct number or address; the address bus provides the means by which the microprocessor can access every location in memory.

Term
Address Space
Definition
The total amount of memory addresses that an address bus can contain.
Term
ADSL
Definition

Asymmetric Digital Subscriber Line

A fully digital, dedicated connection to the telephone system that provides download speeds up to 9 Mbps and upload speeds of up to 1 Mbps.
Term
AGP
Definition

Accelerated Graphics Port

A 32/64-bit expansion slot designed by Intel specifically for video that runs at 66 MHz and yields a throughput of at least 254 MBps. Later versions (2X, 4X, 8X) give substantially higher throughput.
Term
ALU
Definition

Arithmetic Logic Unit

The circuit that performs CPU math calculations and logic operations.
Term
Analog
Definition
An analog device uses a physical quantity, such as length or voltage, to represent the value of a number. By contrast, digital storage relies on a coding system of numeric units.
Term
ANSI
Definition

American National Standards Institute

Body responsible for standards such as ASCII.
Term
ANSI Character Set
Definition
The ANSI-standard character set, which defines 256 characters. The first 128 are ASCII, and the second group of 128 contain math and language symbols.
Term
API
Definition

Application Programming Interface

A software definition that describes operating system calls for application software; conventions defining how a service is invoked.
Term
APM
Definition

Advanced Power Management

The BIOS routines that enable the CPU to turn on and off selected peripherals.
Term
Archive Bit
Definition

An attribute of a file that shows whether the file has been backed up since the last change.

Each time a file is opened, changed, or saved, the archive bit is turned on. Some types of backups will turn off this archive bit to indicate that a good backup of the file exists on tape.

Term
ARP
Definition

Address Resolution Protocol

A protocol in the TCP/IP suite used with the command-line utility of the same name to determine the MAC address that corresponds to a particular IP address
Term
ASCII
Definition

American Standard Code for Information Interchange

The industrystandard 8-bit characters used to define text characters, consisting of 96 upper and lowercase letters, plus 32 non-printing control characters, each of which is numbered. These numbers were designed to achieve uniformity among different computer devices for printing and the exchange of simple text documents.
Term
ASPI
Definition

Advanced SCSI Programming Interface

A series of very tight standards that enable SCSI devices to share a common set of highly compatible drivers.
Term
Assembler
Definition

A program that converts symbolically coded programs into object-level machine code.

In an assembler program, unlike a compiler, there is a one-to-one correspondence between human-readable instructions and the machine-language code.

Term
Asynchronous
Definition
Communication whereby the receiving devices must send an
acknowledgment or “ACK” to the sending unit to verify that a piece of data has
been sent.
Term
ATA
Definition

AT Attachment

A type of hard drive and controller.

ATA was designed to replace the earlier ST506 and ESDI drives without requiring replacement of the AT BIOS— hence, AT attachment. These drives are more popularly known as IDE drives. See also ST506, ESDI, and IDE.

ATA/33 A hard drive standard with drive transfer speeds up to 33MB/s. (See Ultra DMA.)

ATA/66 A hard drive standard with drive transfer speeds up to 66MB/s. (See Ultra DMA.)

ATA/100 A hard drive standard with drive transfer speeds up to 100MB/s. (See Ultra DMA.)

Term
ATAPI
Definition

AT Attachment Packet Interface

A series of standards that enable mass storage devices other than hard drives to use the IDE/ATA controllers. Extremely popular with CD-ROM drives and removable media drives like the Iomega Zip drive. (See EIDE.)
Term
AT Bus
Definition
The 16-bit expansion bus used in the IBM Personal Computer and the 32-bit
bus of computers using the Intel 386 and 486 microprocessors.
Term
ATX
Definition

AT eXtended

A popular motherboard form factor, which generally replaced the AT form factor.
Term
AUI
Definition

Attachment Unit Interface

Also called DIX The standard connector used with 10Base5 Ethernet; a 15-pin female DB connector.
Term
AUTOEXEC.BAT
Definition

A batch file that DOS executes when you start or restart the system.

AUTOEXEC.BAT is not necessary, but when you’re running a computer to which you’ve attached several devices and several different software applications, the file is essential for efficient operation.

AUTOEXEC.BAT files commonly include PATH statements that tell DOS where to find application programs, and commands to install a mouse or operate your printer.

Term
Backbone
Definition
A generalized term defining a primary cable or system that connects networks
together.
Term
Background Processing
Definition
Users may use a terminal for one project and concurrently submit a job that is placed in a background queue that the computer will run as
resources become available. Also refers to any processing in which a job runs without being connected to a terminal.
Term
Backside Bus
Definition

The set of wires that connect the CPU to Level 2 cache.

First appearing in the Pentium Pro, most modern CPUs have a special backside bus. Some buses, such as that in the later Celeron processors (300A and beyond), run at the full speed of the CPU, whereas others run at a fraction.

Earlier Pentium IIs, for example, had backside buses running at half the speed of the processor. See also Frontside Bus and External Data Bus.

Term
Bandwidth
Definition

A piece of the spectrum occupied by some form of signal, such as television, voice, fax data, etc.

Signals require a certain size and location of bandwidth in order to be transmitted. The higher the bandwidth, the faster the signal transmission, allowing for a more complex signal such as audio or video.

Because bandwidth is a limited space, when one user is occupying it, others must wait their turn. Bandwidth is also the capacity of a network to transmit a given amount of data during a given period.

Term
Bank
Definition
The total number of SIMMs that can be accessed simultaneously by the chipset.
The “width” of the external data bus divided by the “width” of the SIMM sticks.
Term
Baseband
Definition
Digital signaling that has only one signal (a single signal) on the cable at a time. The signals are only in three states: one, zero, and idle.
Term
BASIC
Definition

Beginner’s All-purpose Symbolic Instruction Code

A commonly used personal- computer language first developed at Dartmouth during the 1960s and popularized by Microsoft.
Term
Baud
Definition
One analog cycle on a telephone line. In the early days of telephone data transmission, the baud rate was often analogous to bits-per-second. Due to advanced modulation of baud cycles as well as data compression, this is no longer true.
Term
Binary Numbers
Definition

A number system with a base of 2, unlike the number systems most of us use which have bases of 10 (decimal numbers), 12 (measurement in feet and inches), and 60 (time).

Binary numbers are preferred for computers for precision and economy. An electronic circuit that can detect the difference between two states (on-off, 0-1) is easier and more inexpensive to build than one that could detect the differences among ten states (0-9).

Term
BIOS
Definition

Basic Input/Output Services

Classically, the software routines burned onto the System ROM of a PC. More commonly seen as any software that directly controls a particular piece of hardware.

A set of programs encoded in Read-Only Memory (ROM) on computers. These programs handle startup operations and low-level control of hardware such as disk drives, the keyboard, and monitor.

Term
Bit
Definition

Binary Digit

A bit is a single binary digit. Any device that can be in an on or off state.
Term
BNC Connector
Definition
A connector used for 10Base2 coaxial cable. All BNC connectors have to be locked into place by turning the locking ring 90 degrees.
Term
Boot
Definition
To initiate an automatic routine that clears the memory, loads the operating system, and prepares the computer for use.

The term is derived from “pull yourself up by your bootstraps.” PCs must do that because RAM doesn’t retain program instructions when power is turned off.

A cold boot occurs when the PC is physically switched on. A warm boot loads a fresh OS without turning off the computer, lessening the strain on the electronic circuitry. To do a warm boot, press the CTRL-ALTDELETE keys at the same time twice in rapid succession (the three-fingered salute).

Term
Boot Sector
Definition
The first sector on an IBM-PC hard drive or floppy disk, track 0. The
boot-up software in ROM tells the computer to load whatever program is found there. If a system disk is read, the program in the boot record directs the computer to the root directory to load the operating system.
Term
bps
Definition

Bits Per Second

Measurement of how fast data is moved from one place to another. A 56K modem can move 56,000 bits per second.
Term
Bridge
Definition
A device that connects two networks and passes traffic between them based only on the node address, so that traffic between nodes on one network does not appear on the other network.

For example, an Ethernet bridge only looks at the Ethernet address. Bridges filter and forward packets based on MAC addresses and operate at Level 2 (Data Link layer) of the OSI seven-layer model.

Term
Broadband
Definition
A type of signaling that sends multiple signals (channels) over the cable at the same time. The best example of broadband signaling is cable television. The zero, one, and idle states (see Baseband) exist on multiple channels on the same cable.
Term
Broadcast
Definition
A broadcast is a packet addressed to all machines. In TCP/IP, the general
broadcast address is 255.255.255.255.
Term
Buffer
Definition

Electronic storage, usually DRAM, that holds data moving between two devices.

Buffers are used in situations where one device may send or receive data faster or slower than the other device with which it is in communication.

For example, the BUFFERS statement in DOS is used to set aside RAM for communication with hard drives.

Term
Bus
Definition
A series of wires connecting two or more separate electronic devices that enable those devices to communicate.
Term
Bus Topology
Definition
A configuration wherein all computers connect to the network via a central bus cable.
Term
Byte
Definition
Eight contiguous bits, the fundamental data unit of personal computers. Storing the equivalent of one character, the byte is also the basic unit of measurement for computer storage. Bytes are counted in powers of two.
Term
Cache
Definition
A special area of RAM that stores the data most frequently accessed from the
hard drive. Cache memory can optimize the use of your systems.
Term
Cache Memory
Definition
A special section of fast memory chips set aside to store the information
most frequently accessed from RAM.
Term
CAT3
Definition
Category 3 wire; an EIA/TIA standard for UTP wiring that can operate up to 20 megabits per second.
Term
CAT5
Definition
Category 5 wire; an EIA/TIA standard for UTP wiring that can operate up to 100 megabits per second.
Term
CD-R
Definition

Compact Disk-Recordable

A type of CD technology that accepts a single “burn” but cannot be erased after that one burn.
Term
CD-ROM
Definition

Compact Disk/Read Only Memory

A read-only compact storage disk for audio or video data. Recordable devices, such as CD-Rs, are updated versions of the older CD-ROM players.
Term
CD-RW
Definition

Compact Disk-Rewritable

A type of CD technology that accepts multiple reads/writes like a hard drive.
Term
Chipset
Definition
Electronic chips that handle all of the low-level functions of a PC, which in the original PC were handled by close to 30 different chips. Chipsets usually consist of one, two, or three separate chips embedded into a motherboard to handle all of these functions.
Term
CISC
Definition

Complex-Instruction Set Computing

CISC is a CPU design that enables the processor to handle more complex instructions from the software at the expense of speed. All Intel processors for PCs are CISC processors.
Term
Clock
Definition
An electronic circuit utilizing a quartz crystal that generates evenly spaced pulses at speeds of millions of cycles per second.

The pulses are used to synchronize the flow of information through the computer’s internal communication channels. Some computers also contain a circuit that tracks hours, minutes, and seconds.

Term
Cluster
Definition

The basic unit of storage on a floppy or hard disk.

Two or more sectors are contained in a cluster. When DOS/Windows 9x stores a file on disk, it writes those files into dozens or even hundreds of contiguous clusters. If there aren’t enough contiguous open clusters available, the operating system finds the next open cluster and writes there, continuing this process until the entire file is saved.

The FAT tracks how the files are distributed among the clusters on the disk.

Term
CMOS
Definition

Complementary Metal-Oxide Semiconductor

Originally, the type of nonvolatile RAM that held information about the most basic parts of your PC such as hard drives, floppies, and amount of DRAM.

Today, actual CMOS chips have been replaced by Flash-type non-volatile RAM. The information is the same, however, and is still called CMOS (pronounced see-moss) even though it is now almost always stored on Flash RAM.

Term
Coax
Definition

Short for coaxial.

Cabling in which an internal conductor is surrounded by another, outer conductor, thus sharing the same axis.
Term
Collision
Definition
The result of two nodes transmitting at the same time on a multiple access
network such as Ethernet. Both packets may be lost or partial packets may result.
Term
Collision Domain
Definition

A set of Ethernet segments that receive all traffic generated by any node within those segments.

Repeaters, amplifiers, and hubs do not create separate collision domains, but bridges, routers, and switches do.

Term
COM
Definition

A system name that refers to the serial communications ports available on your computer.

When used as a program extension, .COM indicates an executable program file limited to 64K.

Term
COMMAND.COM
Definition

In DOS, a file that contains the command processor.

This must be present on the startup disk for DOS to run. COMMAND.COM is usually located in the root directory of your hard drive.
Term
Command Processor
Definition
The part of the operating system that accepts input from the user and displays any messages, such as confirmation and error messages.
Term
Concentrator
Definition
A device that brings together at a common center connections to a particular kind of network (such as Ethernet), and implements that network
internally.
Term
CONFIG.SYS
Definition

An ASCII text file in the root directory that contains configuration commands.

CONFIG.SYS enables the system to be set up to configure high, expanded, and extended memories by the loading of HIMEM.SYS and EMM386.EXE drivers, as well as drivers for non-standard peripheral components.

Term
Controller Card
Definition
A card adapter that connects a device, like a disk drive, to the main
computer bus/motherboard.
Term
Conventional Memory
Definition

In any IBM PC-compatible computer, the first 640K of the computer’s RAM.

This amount proved to be insufficient because of programs that demanded more memory and users who wanted to run more than one program at a time.

Many DOS users equipped their systems with extended or expanded memory and the memory management programs needed to access that memory.

Term
CPU
Definition

Central Processing Unit

The “brain” of the computer. The microprocessor that handles the primary calculations for the computer. CPUs are known by names such as Pentium 4 and Athlon.
Term
CRC
Definition

Cyclical Redundancy Check

A very accurate mathematical method that is used to check for errors in long streams of transmitted data.

Before data is sent, the main computer uses the data to calculate a CRC value from the data’s contents. If the receiver calculates a different CRC value from the received data, the data was corrupted during transmission and is resent. Ethernet packets have a CRC code.

Term
C-RIMM
Definition

Continuity RIMM

A passive device added to populate unused banks in a system that uses RAMBUS RIMMs. Also spelled CRIMM.
Term
Crossover Cable
Definition
Special UTP cable used to connect hubs or to connect network cards without a hub. Crossover cables reverse the sending and receiving wire pairs from
one end to the other.
Term
CSMA/CD
Definition

Carrier Sense Multiple Access with Collision Detection

The access method Ethernet systems use in local area networking technologies enabling packets of data to flow through the network ultimately to reach address locations.
Term
Daisy Chain
Definition
A method of connecting together several devices along a bus and managing the signals for each device.
Term
DB-15
Definition
DB connector (female) used in 10Base5 networks. See also DIX and AUI.
Term
DB Connectors
Definition
D-shaped connectors used for a variety of connections in the PC and networking world. Can be male (with prongs) or female (with holes) and have a varying number of pins or sockets.
Term
DDR-SDRAM
Definition
A type of high-speed RAM that handles two signals per clock cycle. Debug To detect, trace, and eliminate errors in computer programs.
Term
Default Gateway
Definition

In a TCP/IP network, the nearest router to a particular host.

This router’s IP address is part of the necessary TCP/IP configuration for communicating with multiple networks using IP.
Term
Device Driver
Definition
A subprogram to control communications between the computer and peripherals.
Term
DHCP
Definition

Dynamic Host Configuration Protocol

A protocol that enables a DHCP server to set TCP/IP settings automatically for a DHCP client.
Term
Differential Backup
Definition
Similar to an incremental backup. Backs up the files that have been changed since the last backup. This type of backup does not change the state of the archive bit.
Term
DIMM
Definition

Dual Inline Memory Module

A type of DRAM packaging, similar to SIMMs with the distinction that each side of each tab inserted into the system performs a separate function. Comes in a compact 72-pin SO DIMM format, and full size 144- and 168-pin formats.
Term
Disk Striping
Definition
Process by which data is spread among multiple (at least two) drives. It
increases speed for both reads and writes of data. Considered RAID level 0, because it does not provide fault tolerance.
Term
Disk Striping with Parity
Definition

Provides fault tolerance by writing data across multiple drives and then including an additional drive, called a parity drive, that stores information to rebuild the data contained on the other drives.

Disk striping with parity requires at least three physical disks: two for the data and a third for the parity drive. It provides data redundancy at RAID levels 3–5 with different options.

Term
DIX Connector
Definition

Digital, Intel, Xerox

Also called an AUI Connector The DIX standard was the original implementation of Ethernet. The DIX connector is the standard connector used with 10Base5 Ethernet.
Term
DMA
Definition

Direct Memory Access

A technique that some PC hardware devices use to transfer data to and from the memory without using the CPU.
Term
DNS
Definition

Domain Name System

A TCP/IP name resolution system that translates a host name into an IP address.
Term
Domain
Definition

Term used to describe groupings of users, computers, or networks.

In Microsoft networking, a domain is a group of computers and users that share a common account database, called a SAM, and a common security policy.

On the Internet, a domain is a group of computers that share a common element in their hierarchical name.

Other types of domains exist—e.g., collision domain, etc.

Term
DOSKEY
Definition
A DOS utility that enables you to type more than one command on a line, store and retrieve previously used DOS commands, create stored macros, and customize all DOS commands.
Term
Dot-Matrix Printer
Definition
A printer that creates each character from an array of dots. Pins striking a ribbon against the paper, one pin for each dot position, form the dots.
The printer may be a serial printer (printing one character at a time) or a line printer.
Term
Double Word
Definition
A group of 32 binary digits. Four bytes.
Term
DRAM
Definition

Dynamic Random-Access Memory

The memory used to store data in most personal computers. DRAM stores each bit in a “cell” composed of a transistor and a capacitor.

Because the capacitor in a DRAM cell can only hold a charge for a few milliseconds, DRAM must be continually refreshed, or rewritten, to retain its data.

Term
DSL
Definition

Digital Subscriber Line

A high-speed Internet connection technology that uses a regular telephone line for connectivity.

DSL comes in several varieties, including Asynchronous (ADSL) and Synchronous (SDSL), and many speeds. Typical home-user DSL connections are ADSL with a download speed of up to 1.5 Mbps and an upload speed of 384 Kbps.

Term
Duplexing
Definition
Also called Disk Duplexing or Drive Duplexing Similar to mirroring in that data is written to and read from two physical drives, for fault tolerance. Separate controllers are used for each drive, both for additional fault tolerance and additional speed. Considered RAID level 1.
Term
DVD
Definition

Digital Versatile Disk

A CD media format that provides for 4–17 GB of video or data storage.
Term
EDB
Definition

External Data Bus

The primary data highway of all computers. Everything in your computer is tied either directly or indirectly to the external data bus. See also Frontside Bus and Backside Bus.
Term
EIDE
Definition

Enhanced IDE

A marketing concept of hard drive maker Western Digital, encompassing four improvements for IDE drives. These improvements included 528MB drives, four devices, increase in drive throughput, and non-hard drive devices. See also ATAPI, PIO.
Term
EISA
Definition

Enhanced ISA

An improved expansion bus, based on the ISA bus, with a top speed of 8.33 MHz, a 32-bit data path, and a high degree of self-configuration. Backwardly compatible with legacy ISA cards.
Term
EMI
Definition

Electro-Magnetic Interference

EMI is electrical interference from one device to another, resulting in poor performance of the device being interfered with.

An example is having static on your TV while running a blow dryer, or placing two monitors too close together and getting a “shaky” screen.

Term
EMM386.EXE
Definition
An expanded memory emulator that enables DOS applications to use the extended memory as if it were expanded memory. EMM386.EXE also enables the user to load device drivers and programs into the upper memory area.
Term
EMS
Definition

Expanded Memory Specification

A method of memory management developed by Intel, Lotus, and Microsoft that enabled MS-DOS computers to use memory exceeding the 640K limit imposed by MS-DOS.

Memory that conforms to this standard is called expanded memory. Originally, this standard required that a special hardware device be added to the computer, but that was quickly supplanted by a less efficient but much cheaper software solution.

Expanded memory has been made almost obsolete by the Windows environment, which isn’t limited by the 640K barrier. EMS is now required almost solely by DOS-based games.

Term
Encapsulation
Definition

Refers here to the process of putting the packets from one protocol inside the packets of another protocol.

An example of this is TCP/IP encapsulation in NetWare servers, where IPX/SPX packets are placed inside TCP/IP packets, enabling Novell NetWare to use TCP/IP for transport while still allowing the network operating system to get the data it needs from IPX/SPX.

Term
ESDI
Definition

Enhanced Small Device Interface

Second-generation hard drives, distinguished from their predecessors—ST506—by greater data density and lack of dependence on CMOS settings. Completely obsolete.
Term
Ethernet
Definition
Name coined by Xerox for the first standard of network cabling and protocols. Ethernet is based on a bus topology.
Term
Expansion Bus
Definition
Set of wires going to the CPU, governed by the expansion bus crystal,
directly connected to expansion slots of varying types (ISA, PCI, AGP, etc.).
Depending on the type of slots, the expansion bus runs at a percentage of the main system speed (8.33-66 MHz).
Term
External Data Bus (EDB)
Definition
The primary data highway of all computers. Everything in your computer is tied either directly or indirectly to the external data bus. See also
Frontside Bus and Backside Bus.
Term
Fast Ethernet
Definition
Any of several flavors of Ethernet that operate at 100 megabits per
second.
Term
FAT
Definition

File Allocation Table

A hidden table of every cluster on a hard disk. The FAT records how files are stored in distinct clusters. The address of the first cluster of the file is stored in the directory file.

In the FAT entry for the first cluster is the address of the second cluster used to store that file.

In the entry for the second cluster for that file is the address for the third cluster, and so on until the final cluster, which gets a special ‘end of file’ code.

This table is the only way DOS knows where to access files. There are two FATs, mirror images of each other, in case one is destroyed or damaged.

Term
FAT16
Definition
File allocation table that uses 16 bits for addressing clusters. Commonly used with DOS and Windows 95 systems.
Term
FAT32
Definition

File allocation table that uses 32 bits for addressing clusters. Commonly used with Windows 98 and Windows ME systems.

Some Windows 2000 Professional systems also use FAT32, although most use the more robust NTFS.

Term
Fault Tolerance
Definition
The ability of any system to continue functioning after some part of the system has failed. RAID is an example of a hardware device that provides fault tolerance.
Term
FDDI
Definition

Fiber Distributed Data Interface

A standard for transmitting data on optical fiber cables at a rate of around 100 million BPS.
Term
FireWire
Definition

An IEEE 1394 standard to send wide-band signals over a thin connector system that plugs into TVs, VCRs, TV cameras, PCs, etc.

This serial bus, developed by Apple and Texas Instruments, enables connection of 60 devices at speeds ranging from 100 to 400 megabits per second.

Term
Flash ROM
Definition

A type of ROM technology which can be electrically reprogrammed while still in the PC.

Flash is the overwhelmingly most common storage medium of BIOS in PCs today, as it can be upgraded without even having to open the computer on most systems.

Term
Form Factor
Definition
A standard for the physical organization of motherboard components
and motherboard size. The most common form factors are ATX, NLX, and AT.
Term
FPM
Definition

Fast Page Mode

DRAM that uses a “paging” function to increase access speed and to lower production costs. Virtually all DRAMS are FPM DRAM. The name FPM is also used to describe older style, non-EDO DRAM.
Term
Frame
Definition

Basic component of communication over a network.

A group of bits of fixed maximum size and well-defined format that is switched and transmitted as a complete whole through a network. It contains source and destination address, data, and control information. See also Packet.

Term
Frontside Bus
Definition

Name for the wires that connect the CPU to the main system RAM.

Generally running at speeds of 66-133 MHz. Distinct from the Expansion Bus and the Backside Bus, though it shares wires with the former.

Term
FTP
Definition

File Transfer Protocol

A set of rules that allows two computers to talk to one another as a file transfer is carried out. This is the protocol used when you transfer a file from one computer to another across the Internet.
Term
Full-Duplex
Definition
Describes any device that can send and receive data simultaneously.
Term
Gateway
Definition

The technical meaning is a hardware or software setup that translates between two dissimilar protocols.

For example, Prodigy has a gateway that translates between its internal, proprietary e-mail format and Internet e-mail format.

Another, less technical meaning of gateway is any mechanism for providing access to another system, e.g., AOL might be called a gateway to the Internet. See also Default Gateway

Term
Half-Duplex
Definition
Any device that at any given moment can either send or receive data, but
not both. Most Ethernet transmissions are half-duplex.
Term
Hex (Hexadecimal)
Definition

A base-16 numbering system using 10 digits (0 through 9) and six letters (A through F).

Used in the computer world as a shorthand way to write binary numbers, by substituting one hex digit for a four-digit binary number (for example, hex 9  binary 1001).

Term
HMA
Definition

High Memory Area)

The first 64K–16 bytes of memory above 1 megabyte is known as the HMA. Programs that conform to XMS can use HMA as a direct extension of conventional memory.

Most of the portions of DOS that must be loaded into conventional memory can be loaded into the HMA.

Term
Host
Definition

A single device (usually a computer) on a TCP/IP network that has an IP address—any device that can be the source or destination of a data packet.

A single device (usually a computer) on a TCP/IP network that has an IP address—any device that can be the source or destination of a data packet.

Term
Host ID
Definition
The portion of an IP address that defines a specific machine.
Term
HTML
Definition

HyperText Markup Language)

An ASCII-based script-like language for creating hypertext documents like those on the World Wide Web.
Term
HTTP
Definition

HyperText Transfer Protocol)

Extremely fast protocol used for network file transfers in the WWW environment.
Term
Hub
Definition

An electronic device that sits at the center of a star topology network, providing a common point for the connection of network devices.

In a 10BaseT Ethernet network, the hub contains the electronic equivalent of a properly terminated bus cable; in a Token Ring network, the hub contains the electronic equivalent of a ring.

Term
HyperText
Definition
A document which has been marked up to enable a user to select words or
pictures within the document, click on them, and connect to further information. The basis of the World Wide Web.
Term
IDE
Definition

Intelligent or Integrated Drive Electronics)

A PC specification for small- to medium-sized hard drives in which the controlling electronics for the drive are part of the drive itself, speeding up transfer rates and leaving only a simple adapter (or “paddle”).

IDE only supported two drives per system of no more than 504 megabytes each, and has been completely supplanted by Enhanced IDE.

EIDE supports four drives of over 8 gigabytes each and more than doubles the transfer rate.

The more common name for ATA drives. (See also ATA.)

Term
IEEE
Definition

(Institute of Electronic and Electrical Engineers)

IEEE is the leading standards- setting group in the United States.
Term
IEEE 802.1
Definition
IEEE subcommittee that defined the standards for Higher Layer LAN
Protocols.
Term
IEEE 802.2
Definition
IEEE subcommittee that defined the standards for Logical Link Control.
Term
IEEE 802.3
Definition
IEEE subcommittee that defined the standards for CSMA/CD (a.k.a.
Ethernet).
Term
IEEE 802.7
Definition
IEEE subcommittee that defined the standards for Broadband.
Term
IEEE 802.8
Definition
IEEE subcommittee that defined the standards for Fiber Optic.
Term
IEEE 802.11
Definition
IEEE subcommittee that defined the standards for Wireless.
Term
IEEE 802.14
Definition
IEEE subcommittee that defined the standards for Cable Modems.
Term
Impedance
Definition
The amount of resistance to an electrical signal on a wire. It is used as a relative measure of the amount of data a cable can handle.
Term
Incremental Backup
Definition
A type of backup that backs up all files that have their archive bits turned on, meaning that they have been changed since the last backup. This type of backup turns the archive bits off after the files have been backed up.
Term
I/O
Definition

Input/Output

A general term for reading and writing data to a computer.

The term “input” includes data from a keyboard, pointing device (such as a mouse), or loading a file from a disk.

“Output” includes writing information to a disk, viewing it on a CRT, or printing it to a printer.

Term
IP Address
Definition

Also called Internet Address

The numeric address of a computer connected to the Internet. The IP address is made up of octets of 8-bit binary numbers that are translated into their shorthand numeric values.

The IP address can be broken down into a network ID and a host ID.

Term
IPCONFIG
Definition
A command-line utility for Windows NT servers and workstations that
displays the current TCP/IP configuration of the machine, similar to WINIPCFG and IFCONFIG.
Term
IP
Definition

Internet Protocol

The Internet standard protocol that provides a common layer over dissimilar networks used to move packets among host computers and through gateways if necessary.

Part of the TCP/IP protocol suite.

Term
IRQ
Definition

Interrupt Request,/p>

A signal from a hardware device, such as a modem or a mouse, indicating that it needs the CPU’s attention.

In PCs, IRQs are sent along specific IRQ channels associated with a particular device. It is therefore important to ensure that two devices do not share a common IRQ channel.

Term
ISA
Definition

Industry Standard Architecture

The Industry Standard Architecture design is found in the original IBM PC for the slots on the motherboard that allowed additional hardware to be connected to the computer’s motherboard.

An 8-bit, 8.33 MHz expansion bus was designed by IBM for its AT computer and released to the public domain.

An improved 16-bit bus was also released to the public domain. Various other designs such as IBM’s MicroChannel and EISA bus tried to improve on the design without much popularity.

ISA only supports 8- and 16-bit data paths, so 32-bit alternatives such as PCI and AGP have become popular.

Although ISA slots linger on most motherboards, they are on the way out, replaced by the newer 32-bit slots.

Term
ISDN
Definition

Integrated Services Digital Network

The CCITT (Comité Consutatif Internationale de Télégraphie et Téléphonie) standard that defines a digital method for communications to replace the current analog telephone system.

ISDN is superior to telephone lines because it supports up to 128 Kbps transfer rate for sending information from computer to computer.

It also allows data and voice to share a common phone line.

Term
JPEG
Definition

Joint Photographic Experts Group

A method of formatting images for efficient storage and transfer across phone lines; JPEG files are often a factor of 10 or more times smaller than non-compressed files.

JPEG is a lossy format, meaning that some data is lost when an image is converted.

Most JPEG conversion software enables the user to decide between more or less compression, more coming at the cost of image quality.

JPEG supports 24-bit images (up to 16.7 million colors). Because computers running MS-DOS are limited in their filenames, this format is also referred to as JPG.

Term
Jumper
Definition
A pair of small pins that can be shorted with a “shunt” to configure many different aspects of PCs. Usually used in configurations that are rarely changed, such as master/slave settings on IDE drives.
Term
Kernel
Definition
The core portion of the program that resides in memory and performs the
most essential operating system tasks.
Term
LAN
Definition

Local Area Network

A group of PCs connected together via cabling, radio, or infrared that use this connectivity to share resources such as printers and mass storage.
Term
Layer
Definition

In the communications field, a grouping of related tasks involving the transfer of information.

Also, a level of the OSI reference model used for networking computers.

In graphics work, images can be created in layers, which can be manipulated separately and then flattened into a single image.

Term
LBA
Definition

Logical Block Addressing

A translation (algorithm) of IDE drives promoted by Western Digital as a standardized method for breaking the 504MB limit in IDE drives.

Subsequently universally adopted by the PC industry, LBA is standard on all EIDE drives.

Term
Link Segment
Definition

A networking term referring to a twisted-pair Ethernet segment, formally defined as a point-to-point full duplex medium that connects two and only two MDIs (attachment mechanisms).

Functionally that means an Ethernet cable connected at each end to a computer or another network device.

Term
Local Bus
Definition
A high-speed data path that directly links the computer’s CPU with one or
more slots on the expansion bus. This direct link means signals from an adapter do not have to travel through the computer expansion bus, which is significantly slower.
Term
Logical Address
Definition
An address that describes both a specific network and a specific
machine on that network.
Term
Logical Drives
Definition
Sections of a hard drive that are formatted and assigned a drive letter,
each of which is presented to the user as if it were a separate drive.
Term
Low-Level Format
Definition
Defining the physical location of magnetic tracks and sectors on a
disk.
Term
Machine Language
Definition
A programming language or instruction code that is immediately
interpretable by the hardware of the machine concerned.
Term
MAC
Definition

Media Access Control

Unique 48-bit address assigned to each network card. IEEE assigns blocks of possible addresses to various NIC manufacturers to help ensure that the address is always unique.

The Data Link layer of the OSI model uses MAC addresses for locating machines.

Term
Math Coprocessor—
Definition

Also called Math Unit or Floating-Point Unit (FPU)

A secondary microprocessor whose function is the handling of floating-point arithmetic. Although originally a physically separate chip, math coprocessors are now built into today’s CPUs.

Term
MAU
Definition

Multistation Access Unit

Also called MSAU A hub used in Token Ring networks.
Term
MCA
Definition

Micro Channel Architecture

Expansion bus architecture developed by IBM as the (unsuccessful) successor to ISA. MCA had a full 32-bit design as well as being self-configuring.
Term
MCC
Definition

Memory Controller Chip

The chip that handles memory requests from the CPU. Although once a special chip, it has been integrated into the chipset on all PCs today.
Term
Mesh Topology
Definition
Network wiring scheme where each computer has a dedicated connection
to every other computer in a network.
Term
MHz
Definition

Megahertz

A unit of measure that equals a frequency of one million cycles per second.
Term
Microprocessor
Definition

Also called CPU

The “brain” of a computer. The primary computer chip that determines the relative speed and capabilities of the computer.
Term
MIDI
Definition

Musical Instrument Digital Interface

MIDI is a standard that describes the interface between a computer and a device for simulating musical instruments.

Rather than sending large sound samples, a computer can simply send “instructions” to the instrument describing pitch, tone, and duration of a sound.

MIDI files are therefore very efficient. Because a MIDI file is made up of a set of instructions rather than a copy of the sound, it is easy to modify each component of the file.

Additionally, it is possible to program many channels, or “voices,” of music to be played simultaneously, creating symphonic sound.

Term
Mirroring
Definition
Also called Drive Mirroring Reading and writing data at the same time to
two drives for fault tolerance purposes. Considered RAID level 1.
Term
MMU
Definition

Memory-Management Unit

A chip or circuit that translates virtual memory addresses into physical addresses and may implement memory protection.
Term
Modem
Definition

MOdulator/DEModulator

A device that converts a digital bit stream into an analog signal (modulation) and converts incoming analog signals back into digital signals (demodulation).

The analog communications channel is typically a telephone line and the analog signals are typically sounds.

Term
Motherboard
Definition
The primary circuit board that holds all of the core components of the
computer.
Term
MPEG
Definition

Motion Picture Experts Group

A sophisticated video standard that enables digital video to be compressed using a form of JPEG image compression and a technique called differencing, in which only the differences between frames are recorded, rather than the frame itself.

Term
MP3
Definition

MPEG-1 Audio Layer 3

An audio compression scheme used extensively on the Internet.

Term
MSAU
Definition

Multistation Access Unit—Also called MAU

A hub used in Token Ring networks.
Term
Multiplexer
Definition
A device that merges information from multiple input channels to a single
output channel.
Term
Multitasking
Definition
The process of running multiple programs or tasks on the same computer
at the same time.
Term
NBTSTAT
Definition
A command-line utility used to check the current NetBIOS name cache on
a particular machine. The utility compares NetBIOS names to their corresponding IP addresses.
Term
NetBEUI
Definition

NetBIOS Extended User Interface

A protocol supplied with all Microsoft networking products that operates at the Transport layer. Also a protocol suite that includes NetBIOS. NetBEUI does not support routing.

Term
NetBIOS
Definition

Network Basic Input/Output System

A protocol that operates at the Session layer of the OSI seven-layer model. This protocol creates and manages connections based on the names of the computers involved.
Term
NETSTAT
Definition
A command-line utility used to examine the sockets-based connections
open on a given host.
Term
Network
Definition

A collection of two or more computers interconnected by telephone lines, coaxial cables, satellite links, radio, and/or some other communication technique.

A computer “network” is a group of computers that are connected together and that communicate with one another for a common purpose.

Computer networks support “people and organization” networks, users who also share a common purpose for communicating.

Term
Network ID
Definition
A number that identifies the network on which a device or machine exists. This number exists in both IP and IPX protocol suites.
Term
NIC
Definition

Network Interface Card

An expansion card that enables a PC to physically link to a network.
Term
Node
Definition
A member of a network or a point where one or more functional units interconnect transmission lines.
Term
NOS
Definition

Network Operating System

An NOS is an operating system that provides basic file and supervisory services over a network.

While each computer attached to the network will have its own OS, the NOS describes which actions are allowed by each user and coordinates distribution of networked files to the user who requests them.

Term
NTFS
Definition

NT File System

A file system for hard drives that enables object-level security, long filename support, compression, and encryption. NTFS 4.0 debuted with Windows NT 4.0. Windows 2000 comes with the updated NTFS 5.0.
Term
Ohm
Definition
Electronic measurement of a cable’s impedance.
Term
OSI
Definition

Open Systems Interconnect

An international standard suite of protocols defined by International Organization for Standardization (ISO) that implements the OSI reference model for network communications between computers.
Term
OSI Seven-Layer Model
Definition

An architecture model based on the OSI protocol suite that defines and standardizes the flow of data between computers. The seven layers are:

  • Layer 1 The Physical layer defines hardware connections and turns binary into physical pulses (electrical or light). Repeaters and hubs operate at the Physical layer.
  • Layer 2 The Data Link layer identifies devices on the Physical layer. MAC addresses are part of the Data Link layer. Bridges operate at the Data Link layer.
  • Layer 3 The Network layer moves packets between computers on different networks. Routers operate at the Network layer. IP and IPX operate at the Network layer.
  • Layer 4 The Transport layer breaks data down into manageable chunks. TCP, UDP, SPX, and NetBEUI operate at the Transport layer.
  • Layer 5 The Session layer manages connections between machines. NetBIOS and Sockets operate at the Session layer.
  • Layer 6 The Presentation layer, which can also manage data encryption, hides the differences between various types of computer systems.
  • Layer 7 The Application layer provides tools for programs to use to access the network (and the lower layers). HTTP, FTP, SMTP, and POP3 are all examples of protocols that operate at the Application layer.
Term
OSI Layer 1 (from bottom)
Definition

The Physical layer

defines hardware connections and turns binary into physical pulses (electrical or light). Repeaters and hubs operate at the Physical layer.
Term
OSI Layer 2 (from bottom)
Definition

The Data Link layer

identifies devices on the Physical layer. MAC addresses are part of the Data Link layer. Bridges operate at the Data Link layer.
Term
OSI Layer 3 (from bottom)
Definition

The Network layer

moves packets between computers on different networks. Routers operate at the Network layer. IP and IPX operate at the Network layer.
Term
OSI Layer 4 (from bottom)
Definition

The Transport layer

breaks data down into manageable chunks. TCP, UDP, SPX, and NetBEUI operate at the Transport layer.
Term
OSI Layer 5 (from bottom)
Definition

The Session layer

manages connections between machines. NetBIOS and Sockets operate at the Session layer.
Term
OSI Layer 6 (from bottom)
Definition

The Presentation layer

which can also manage data encryption, hides the differences between various types of computer systems.
Term
OSI Layer 7 (from bottom)
Definition

The Application layer

provides tools for programs to use to access the network (and the lower layers). HTTP, FTP, SMTP, and POP3 are all examples of protocols that operate at the Application layer.
Term
Overclocking
Definition
To run a CPU or video processor faster than its rated speed.
Term
Packet
Definition
Basic component of communication over a network. A group of bits of fixed
maximum size and well-defined format that is switched and transmitted as a complete whole through a network. It contains source and destination address, data, and control information. See also Frame.
Term
Parallel Port
Definition
A connection for the synchronous, high-speed flow of data along parallel
lines to a device, usually a printer.
Term
Parity
Definition

A method of error detection where a small group of bits being transferred is compared to a single “parity” bit that is set to make the total bits odd or even.

The receiving device reads the parity bit and determines if the data is valid based on the oddness or evenness of the parity bit.

Term
Partition
Definition
A section of the storage area of a hard disk. A partition is created during initial preparation of the hard disk, before the disk is formatted.
Term
Path
Definition
The route the operating system must follow to find an executable program
stored in a subdirectory.
Term
PCI
Definition

Peripheral Component Interconnect)

A design architecture for the sockets on the computer motherboard that enable system components to be added to the computer.

PCI is a “local bus” standard, meaning that devices added to a computer through this port will use the processor at the motherboard’s full speed (up to 33 MHz), rather than at the slower 8 MHz speed of the regular bus. In addition to moving data at a faster rate, PCI moves data 32 or 64 bits at a time, rather than the 8 or 16 bits that the older ISA buses supported.

Term
PCMCIA
Definition

Personal Computer Memory Card International Association

A consortium of computer manufacturers who devised the standard for credit card-sized adapter cards that add functionality in many notebook computers, PDAs, and other computer devices.

The simpler term “PC Card” has become more common in referring to these cards.

Term
Peer-to-Peer Networks
Definition
A network in which each machine can act as both a client and
a server.
Term
Physical Address
Definition
Defines a specific machine without any reference to its location or network. A MAC address is an example of a physical address.
Term
Pipeline
Definition
A processing methodology where multiple calculations take place simultaneously by being broken into a series of steps. Often used in CPUs and video processors.
Term
Platen
Definition
The cylinder that guides paper through an impact printer and provides a backing surface for the paper when images are impressed onto the page.
Term
Plug and Play
Definition

Also called PnP

A combination of smart PCs, smart devices, and smart operating systems that automatically configure all the necessary system resources and ports when you install a new peripheral device.
Term
POP
Definition

Post Office Protocol

Also called Point Of Presence

Refers to the way e-mail software such as Eudora gets mail from a mail server. When you obtain a SLIP, PPP, or shell account you almost always get a POP account with it; and it is this POP account that you tell your e-mail software to use to get your mail.

Term
Port
Definition
That portion of a computer through which a peripheral device may communicate. Often identified with the various plug-in jacks on the back of your computer. On a network hub, it is the connector that receives the wire link from a node.
Term
Port Number
Definition
Number used to identify the requested service (such as SMTP or FTP) when connecting to a TCP/IP host. Some example port numbers include 80
(HTTP), 20 (FTP), 69 (TFTP), 25 (SMTP), and 110 (POP3).
Term
PPP
Definition

Point-to-Point ProtocolM/p> A protocol that enables a computer to connect to the Internet through a dial-in connection and enjoy most of the benefits of a direct connection. PPP is considered to be superior to SLIP because of its error detection and data compression features, which SLIP lacks, and the ability to use dynamic IP addresses.

Term
PPTP
Definition

Point-to-Point Tunneling Protocol

Protocol that works with PPP to provide a secure data link between computers using encryption.
Term
Prompt
Definition
A character or message provided by an operating system or program to indicate
that it is ready to accept input.
Term
Protected Mode
Definition
The operating mode of a CPU allowing more than one program to be run while ensuring that no program can corrupt another program currently running.
Term
Protocol
Definition
An agreement that governs the procedures used to exchange information
between cooperating entities; usually includes how much information is to be sent, how often it is sent, how to recover from transmission errors, and who is to receive the information.
Term
Protocol Stack
Definition
The actual software that implements the protocol suite on a particular
operating system.
Term
Protocol Suite
Definition
A set of protocols that are commonly used together and operate at different
levels of the OSI seven-layer model.
Term
PSTN
Definition

Public Switched Telephone Network

Also called POTS (Plain Old Telephone Service)

Most common type of phone connection that takes your sounds—translated into an analog waveform by the microphone—and transmits them to another phone.

Term
RAID
Definition

Redundant Array of Inexpensive Devices or Disks

A way of creating a faulttolerant storage system. There are six levels.

  • Level 0 uses byte-level striping and provides no fault tolerance.
  • Level 1 uses mirroring or duplexing.
  • Level 2 uses bit-level striping.
  • Level 3 stores error-correcting information (such as parity) on a separate disk, and uses data striping on the remaining drives.
  • Level 4 is level 3 with blocklevel striping.
  • Level 5 uses block-level and parity data striping.
Term
Rambus
Definition
A patented RAM technology that uses accelerated clocks to provide very
high-speed memory.
Term
RAM
Definition

Random-Access Memory

Memory that can be accessed at random, that is, in which any memory address can be written to or read from without touching the preceding address. This term is often used to mean a computer’s main memory.

Term
Real Mode
Definition
The original 64K segmented memory, single-tasking operating mode of
the Intel 8086 and 8088 CPUs.
Term
Repeater
Definition
A device that takes all of the data packets it receives on one Ethernet segment and re-creates them on another Ethernet segment. This allows for longer cables or more computers on a segment. Repeaters operate at Level 1 (Physical) of the OSI seven-layer model.
Term
RG-58
Definition
Coaxial cabling used for 10Base2 networks.
Term
RIMM
Definition
An individual stick of Rambus RAM.
Term
Ring Topology
Definition
Network wiring scheme where all the computers on a network attach
to a central ring of cable.
Term
RISC
Definition

Reduced-Instruction Set Computing

RISC is a CPU design that requires the processor to handle very simple instructions. This enables the processor to execute these instructions at a very high speed. Motorola’s PowerPC processors, used on both Mac and PC platforms, use RISC design.
Term
RJ
Definition

Registered Jack

UTP cable connectors, used for both telephone and network connections.
Term
RJ-11
Definition
Type of connector for four-wire UTP; usually found in telephone connections.
Term
RJ-45
Definition
Type of connector for eight-wire UTP; usually found in network connections
and used for 10BaseT and 100BaseT networking.
Term
ROM
Definition

Read Only Memory

The generic term for non-volatile memory that can be read from but not written to. This means that code and data stored in ROM cannot be corrupted by accidental erasure.

Additionally, ROM retains its data when power is removed, which makes it the perfect medium for storing BIOS data or information such as scientific constants.

Term
Root Directory
Definition
The directory that contains all other directories.
Term
Router
Definition

A device connecting separate networks that forwards a packet from one network to another based on the network address for the protocol being used.

For example, an IP router looks only at the IP network number.

Routers operate at Layer 3 (Network) of the OSI seven-layer model.

Term
Routing Table
Definition
List of paths to various networks required by routers. This can be built
manually or automatically.
Term
RS-232C
Definition
A standard port recommended by the Electronics Industry Association for
serial devices.
Term
SCSI
Definition

Small Computer System Interface

A powerful and flexible peripheral interface popularized on the Macintosh and used to connect hard drives, CD-ROM drives, tape drives, scanners, and other devices to PCs of all kinds.

Because SCSI is less efficient at handling small drives than IDE, it did not become popular on IBMcompatible computers until price reductions made these large drives affordable.

Normal SCSI enables up to seven devices to be connected through a single bus connection, whereas Wide SCSI can handle 15 devices attached to a single controller.

Term
SDRAM
Definition

Synchronous DRAM

DRAM that is tied to the system clock and thus runs much faster than traditional FPM and EDO RAM.
Term
Sector
Definition
A segment of one of the concentric tracks encoded on the disk during a lowlevel format. Sectors hold 512 bytes of data.
Term
Server
Definition
A computer that shares its resources, such as printers and files, with other computers on a network. An example of this is a Network File System Server that shares its disk space with a workstation that does not have a disk drive of its own.
Term
Server-Based Network
Definition
A network in which one or more systems function as dedicated file, print, or application servers, but do not function as clients.
Term
Session
Definition
Networking term used to refer to the logical stream of data flowing between
two programs and being communicated over a network. There may be many different sessions emanating from any one node on a network.
Term
Shunt
Definition
A tiny connector of metal enclosed in plastic that creates an electrical connection between two posts of a jumper.
Term
SIMM
Definition

Single Inline Memory Module

A type of DRAM packaging distinguished by having a number of small tabs that install into a special connector. Each side of each tab is the same signal. SIMMs come in two common sizes: 30-pin and 72-pin.
Term
SL Enhanced
Definition
A CPU that has the ability to turn off selected peripherals as well as run
on low (3.3 V or less) power. See also SMM.
Term
SLIP
Definition

Serial Line Internet Protocol

A protocol that enables a computer to connect to the Internet through a dial-in connection and enjoy most of the benefits of a direct connection.

SLIP has been nearly completely replaced by PPP, which is considered superior to SLIP because of its error detection and data compression, features that SLIP lacks, and the ability to use dynamic IP addresses.

Term
SMB
Definition

Server Message Blocks

Protocol used by Microsoft clients and servers to share file and print resources.
Term
SMM
Definition

System Management Mode

A special CPU mode that enables the CPU to reduce power consumption via the selective shutdown of peripherals.
Term
SMTP
Definition

Simple Mail Transport Protocol

The main protocol used to send electronic mail on the Internet.
Term
SNMP
Definition

Simple Network Management Protocol

A set of standards for communication with devices connected to a TCP/IP network. Examples of these devices include routers, hubs, and switches.
Term
Socket
Definition
A combination of a port number and an IP address that uniquely identifies a
connection. Also a mounting area for an electronic chip.
Term
SPS
Definition

Stand-by Power Supply or System

A device that supplies continuous clean power to a computer system immediately following a power failure. See also UPS.
Term
SQL
Definition

Structured Query Language

A language created by IBM that relies on simple English statements to perform database queries. SQL enables databases from different manufacturers to be queried using a standard syntax.
Term
SRAM
Definition

Static RAM

A type of RAM that uses a flip-flop type circuit rather than the typical transistor/capacitor of DRAM to hold a bit of information. SRAM does not need to be refreshed and is faster than regular DRAM. Used primarily for cache.
Term
Star Bus Topology
Definition
This is a hybrid of the Star and Bus topologies. This topology uses a physical star, where all nodes connect to a single wiring point such as a hub, and a logical bus that maintains the Ethernet standards. One benefit of a Star Bus topology is fault tolerance.
Term
Star Topology
Definition
Network wiring scheme where computers on a network connect to a central wiring point.
Term
Static Routing
Definition
Process by which routers in an internetwork obtain information about
paths to other routers. This information must be supplied manually.
Term
STP
Definition

Shielded Twisted Pair

A popular cabling for networks composed of pairs of wires twisted around each other at specific intervals. The twists serve to reduce interference (also called crosstalk). The more twists, the less interference.

The cable has metallic shielding to protect the wires from external interference.

Token Ring networks are the only common network technology that uses STP, although Token Ring more often now uses UTP.

Term
Subnet
Definition
In a TCP/IP internetwork, each independent network is referred to as a subnet.
Term
Subnet Mask
Definition
The value used in TCP/IP settings to divide the IP address of a host into
its component parts: network ID and host ID.
Term
SVGA
Definition
Any display mode that goes beyond VGA (640  480 at 16 colors) in either resolution or color depth can be labeled as SVGA, or Super VGA.
Term
Switch
Definition
A device that filters and forwards traffic based on some criteria. A bridge and a router are both examples of switches
Term
Synchronous
Definition
Describes a connection between two electronic devices where neither
must acknowledge (“ACK”) when receiving data.
Term
System BIOS
Definition
The primary set of BIOS stored on an EPROM or Flash chip on the
motherboard. Defines the BIOS for all the assumed hardware on the motherboard, such as keyboard controller, floppy drive, basic video, RAM, etc.
Term
TCP
Definition

Transmission Control Protocol

Part of the TCP/IP protocol suite, TCP operates at Layer 4 (the Transport layer) of the OSI seven-layer model. TCP is a connection-oriented protocol.
Term
TCP/IP
Definition

Transmission Control Protocol/Internet Protocol

A set of communication protocols developed by the U.S. Department of Defense that enables dissimilar computers to share information over a network.
Term
Terminating Resistors
Definition

Any device that absorbs excess electrical signals off a wire.

Examples include the device used at each end of a coaxial cable to absorb the excess electrical signals—this helps avoid signal bounce or reflection.

The level of resistance in an RG-58 coaxial cable requires these to have 50 Ohm impedance. Another device with the same name is used to terminate the ends of the SCSI chain.

Term
Token Ring
Definition
A LAN and protocol in which nodes are connected together in a ring; a
special packet called a token passed from node to node around the ring controls communication. A node can send data only when it receives the token and the token is not in use. This avoids the collision problems endemic to Ethernet networks.
Term
Topology
Definition
The pattern of interconnections in a communications system between devices, nodes, and associated input and output stations. Also describes how computers
connect to each other without regard to how they actually communicate.
Term
TSR
Definition

Terminate and Stay Resident

A DOS program that closes immediately after starting up, but leaves a tiny piece of itself in memory.

TSRs are used to handle a broad cross-section of DOS-level system needs, such as running hardware (MOUSE.COM) or applying higher-level functionality to hardware already under the control of device drivers.

MSCDEX.EXE, for example, assigns a drive letter to a CD-ROM drive after the CD-ROM driver has loaded in CONFIG.SYS.

Term
UART
Definition

Universal Asynchronous Receiver/Transmitter

A UART is a device that turns serial data into parallel data. The cornerstone of serial ports and modems.
Term
UDP
Definition

User Datagram Protocol

Part of the TCP/IP protocol suite, UDP is an alternative to TCP. UDP is a connectionless protocol.
Term
Ultra DMA
Definition

A hard drive technology that enables drives to use direct memory addressing.

Ultra DMA mode 3 drives—called ATA/33—have data transfer speeds up to 33MB/s. <.P>

Mode 4 and 5 drives—called ATA/66 and ATA/100, respectively—transfer data at up to 66MB/s for mode 4 and 100MB/s for mode 5. Both modes 4 and 5 require an 80-pin cable and a compatible controller in order to achieve these data transfer rates.

Term
UMA
Definition

Upper Memory Area

The memory area between the first 640K and 1024K reserved for system use and device drivers.
Term
UMB
Definition

Upper Memory Block

The open areas of the Reserved Memory (the 384K block above Conventional Memory) loading Adapter ROM and device drivers.
Term
UPS
Definition

Uninterruptible Power Supply

A device that supplies continuous clean power to a computer system the whole time the computer is on. Protects against power outages and sags. The term UPS is often used mistakenly when people mean SPS (Stand-by Power Supply).
Term
URL
Definition

Uniform Resource Locator

An address that defines the location of a resource on the Internet. URLs are used most often in conjunction with HTML and the World Wide Web.
Term
USB
Definition

Universal Serial Bus

A 12 Mbps serial interconnect for keyboards, printers, joysticks, and many other devices. Enables hot-swapping and daisy chaining devices.
Term
UTP
Definition

Unshielded Twisted Pair

A popular type of cabling for telephone and networks, composed of pairs of wires twisted around each other at specific intervals. The twists serve to reduce interference (also called crosstalk). The more twists, the less interference. The cable has no metallic shielding to protect the wires from external interference, unlike its cousin, STP. 10BaseT uses UTP, as do many other networking technologies. UTP is available in a variety of grades, called categories, as defined here:

  • Category 1 UTP Regular analog phone lines—not used for data communications
  • Category 2 UTP Supports speeds up to 4 megabits per second
  • Category 3 UTP Supports speeds up to 16 megabits per second
  • Category 4 UTP Supports speeds up to 20 megabits per second
  • Category 5 UTP Supports speeds up to 100 megabits per second
Term
VGA
Definition

Video Graphics Array

The standard for the video graphics adapter that was built into IBM’s PS/2 computer. It supports 16 colors in a 640  480 pixel video display, and quickly replaced the older CGA (Color Graphics Adapter) and EGA (Extended Graphics Adapter) standards.
Term
VLB
Definition

VESA Local Bus

VESA Local Bus is a design architecture for the sockets on the computer motherboard that enable system components to be added to the computer. VLB was the first “local bus” standard, meaning that devices added to acomputer through this port would use the processor at its full speed, rather than at the slower 8 MHz speed of the regular bus.

In addition to moving data at a faster rate, VLB moves data 32 bits at a time, rather than the 8 or 16 bits that the older ISA buses supported. Although VLB was common on machines using Intel’s 486 CPU, modern computers now use PCI buses instead.

Term
Volatile
Definition
Memory that must have constant electricity in order to retain data.
Term
VRAM
Definition

Video RAM

A type of memory in a video display adapter that’s used to create the image appearing on the CRT screen. VRAM uses dual-ported memory, which enables simultaneous reads and writes, making it much quicker than DRAM.
Term
Warm Boot
Definition
A system restart performed after the system has been powered and operating.
This clears and resets the memory, but does not stop and start the hard drive.
Term
WAV
Definition

Windows Audio Format

The default sound format for Windows.
Term
WINIPCFG
Definition
A command-line utility for Windows 9x machines that displays the current
TCP/IP configuration of the machine; similar to IPCONFIG and IFCONFIG
Term
WINS
Definition

Windows Internet Name Service

A name resolution service that resolves NetBIOS names to IP addresses.
Term
Winsock
Definition

WINdows SOCKets

Microsoft Windows implementation of the TCP/IP Sockets interface.
Term
Word
Definition
A group of 16 binary digits or two bytes.
Term
WS
Definition

Wait State

A microprocessor clock cycle in which nothing happens.
Term
XGA
Definition

Extended Graphics Array

IBM video display to bring 1,024  768 resolution to monitors. Can display 65,536 colors at low resolution, and 256 at high resolution.
Term
Xmodem
Definition
A file transfer protocol (FTP) that provides error-free asynchronous communications through telephone lines.
Term
XMS
Definition

Extended Memory Services

The RAM above 1MB that is installed directly on the motherboard, and is directly accessible to the microprocessor. Usually shortened to simply “extended memory.”
Term
Ymodem
Definition
A file transfer protocol (FTP) that is more robust than Xmodem; it features
a time and date stamp transfer, as well as batch file transfers.
Term
ZIF Socket
Definition

Zero Insertion Force Socket

A socket for CPUs that enables insertion of a chip without much pressure. Intel promoted the ZIF socket with its overdrive upgrades. The chip is dropped into the socket’s holes and a small lever is flipped to lock them in. Somewhat replaced in modern motherboards by Slot 1 and Slot A architecture, but still in style in Super Socket 7, Socket A, and Socket 370 motherboards.
Term
Zmodem
Definition
Streaming synchronous file transfer protocol (FTP) used by communication
software. Very popular for downloading.
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