Terms
Glossary
A
B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A
AGP
See Advanced Graphics Port
AIMM
AGP inline memory module (See Advanced Graphics Port)
Access
Time
The average time interval between a storage peripheral
(usually a disk drive or semiconductor memory) receiving
a request to read or write a certain location and returning
the value read or completing the write.
Advanced
Graphics Port
The advanced graphics port (AGP) bus allows the graphics
controller to directly access texture map data from the
main memory rather than having to move it to the graphic
controllers' local memory first. This helps the system
increase the speed of processing graphics and allows for
a use of a larger portion of memory by "borrowing"
storage for texture maps from main memory.
Array
The area of the RAM that stores the bits. The array consists
of rows and columns, with a cell at each intersection
that can store a bit.
Asynchronous
Memory
Memory that is not synchronized with the system clock.
EDO and FPM are examples of asynchronous memory.
Auto
Precharge
A synchronous DRAM feature that allows the memory chip's
circuitry to close a page automatically at the end of
a burst.
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B
BEDO
Burst EDO is a variant on EDO DRAM in which read or write
cycles are batched in bursts of four. Burst EDO bus speeds
range from 40MHz to 66MHz, as opposed to the 33MHz bus
speeds that can be accomplished using fast page mode or
EDO DRAM.
BGA
See Ball Grid Array
BIOS
Basic input/output system. Often referred to as CMOS,
the BIOS provides an interface for a computer's hardware
and software. The BIOS configuration determines how your
hardware is accessed.
Ball
Grid Array
A type of memory chip with solder balls on the underside
for mounting. Use of BGA allows die package size to be
reduced because there is more surface area for attachment.
Smaller packaging allows more components to be mounted
on a module, making greater densities available. The smaller
package also improves heat dissipation for better performance.
See CSP and FBGA.
Bandwidth
A measure of the capacity of data that can be moved between
two points in a given period of time.
Bank
1. A slot or group of slots that must be populated with
modules of like capacity in order to fulfill the data
width requirement of the CPU
2. A segment of memory on a module, sometimes also referred
to as a row. Modules are either single or dual banked
3. An internal logic segment in a memory component. For
example, a 64Mb SDRAM has 4 banks.
Binary
Numbering system based on two digits: 0 and 1.
Bit
Binary digit. The smallest piece of data (a 1 or a 0)
that a computer recognizes.
Block
A physical unit of information in a logical record. Block
size is usually expressed in bytes.
Block
Diagram
A circuit or system drawing concerned with major functions
and interconnections between functions.
Buffered
Memory
A buffer isolates the memory from the controller to minimize
the load on the chip set. It is typically used when the
system has a high density of memory and/or when a system
has more than 3 memory module sockets.
Burn-in
The process of exercising an integrated circuit at elevated
voltage and temperature. This process accelerates failures
normally seen as "infant mortality" in a chip.
(Those chips that would fail early during actual usage
will fail during burn-in. Those that pass have a life
expectancy much greater than that required for normal
usage.)
Bus
Circuitry that is used to move data
Byte
A series of 8 bits.
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C
CAS
Column address strobe is the signal which tells the DRAM
to accept the given address as a column address. It is
used with RAS and a row address to select a bit within
the DRAM.
CAS-B4-RAS
(CBR)
CAS before RAS. Column address strobe before row address
strobe. A refresh technique in which the DRAM keeps track
of the next row it needs to refresh.
COAST
Cache on a stick. Coast modules are used to upgrade a
motherboard's L2 cache and Tag memory on some socket 7
and older motherboards.
COB
Chip on board. A system in which semiconductor dice are
mounted directly on a PC board and connected with bonded
wires or solder bumps. The dice are usually mechanically
protected with epoxy.
CPU
Central processing unit. The computer chip primarily responsible
for executing instructions.
C-RIMMTM
See Continuity RIMMTM
CSP
See Chip Scale Package.
Cache
A small, fast memory holding recently accessed data, designed
to speed up subsequent access to the same data. Typically
used between a processor and main memory.
Capacitance
The property of a circuit element that allows it to store
an electrical charge.
Check
Bits
Extra data bits provided by a module to support ECC.
Chip
Scale Package
A type of ball grid array in which the package is roughly
the size of the die.
Chip
Set
One or more chips on a motherboard that control the data
flow between the processor, memory, and the other components
of the system.
Clock
rate
The number of pulses emitted from a computer's clock in
one second. It determines the rate at which logical or
arithmetic gating is performed in a synchronous computer.
Column
Part of the memory array. A bit can be stored where a
column and a row intersect.
Compact
Flash
A small flash memory module. The memory chips are enclosed
in a plastic case and retain data after they are removed
from the system. The most common uses for these are in
pagers, handheld computers, cell phones, digital cameras,
and audio players.
Contacts
See Edge Contacts
Continuity
RIMMTM
Modules that are used to fill all unused RIMMTM sockets
in a system. Continuity-RIMMs do not use any active components;
instead, they are used to continue the channel so that
the signal can be properly terminated at the motherboard.
Controller
One of the major units in a computer that interprets and
carries out the instructions in a program.
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D
DDR
Double data rate is a type of SDRAM in which data is sent
on both the rising and falling edges of clock cycles in
a data burst. It is usually referred to as DDR as opposed
to DDR SDRAM.
DDR2
Like DDR, DDR2 is a type of SDRAM in which data is sent
on both the rising and falling edges of clock cycles in
a data burst. DDR2 is the next evolutionary step in the
DDR infrastructure and has additional features built into
it to allow for increased system performance.
DIMM
Dual inline memory module. A module with signal and power
pins on both sides of the board (front and back).
DRAM
Dynamic random access memory. A type of memory component
used to store information in a computer system. "Dynamic"
means the DRAMs need a constant "refresh" (pulse
of current through all of the memory cells) to keep the
stored information. (See also RAM and SRAM.)
Die
An individual rectangular pattern on a wafer that contains
circuitry to perform a specific function. Die are encapsulated
to form the black chips that are then placed on a module.
Dual
Banked
A memory module with two banks or rows. See Bank.
Dynamic
Type of RAM (random access memory). To keep data in the
DRAM, this data needs to be "refreshed" (recharged).
The electric charge fades out of a DRAM like air seeps
out of a balloon. Because of this change, it is called
"dynamic."
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E
ECC
Error correcting code. Logic designed to detect and correct
memory errors.
EDO
Extended data out. An asynchronous DRAM operating mode
that improves access times compared to fast page mode
(FPM) DRAMs.
EEPROM
Electrically erasable, programmable, read-only memory.
EEPROMs differ from DRAMs in that the memory is saved
even if electrical power is lost. Additionally, the memory
can be erased and reprogrammed repeatedly.
Edge
Contacts
See Edge Connector
Edge
Connector
Metal tabs on the edge of a printed circuit board (PCB).
The edge contacts are the interface between the PCB and
the socket that allow the system to communicate with the
memory module.
Electrostatic
Discharge (ESD)
The dissipation of electricity. (In layman's terms, a
"shock.") ESD can easily destroy semiconductor
products, even when the discharge is to small to be felt.
Ethernet
A local area network allowing several computers to transfer
data over a communications cable.
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F
FBGA
Fine pitch ball grid array is a die package with a fine
pitch ball arrangement on the underside of the package
(larger than CSP).
FPM
Fast page mode - A feature used to support faster sequential
access to DRAM by allowing multiple accesses to the currently
open row to be made after supplying the row address just
once.
FSB
See Front Side Bus.
FlashPoint ShareDrives
USB
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FlashPoint ShareDrives takes this technology one step
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.data on FlashPoint pen Drives can
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FlashPoint
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With all of this added technology to the FlashPoint ShareDrives
physical size remains the same as most existing pen drives.
FlashPoint ShareDrives are available in three colors including
white, black and silver.
Flash
Card
A small flash memory module. The memory chips are enclosed
in a plastic case and retain data after they are removed
from the system. The most common uses for these are in
laptops, pagers, handheld computers, cell phones, digital
cameras, and audio players. There are several different
form factors of flash cards, including Compact Flash,
SmartMedia, PCMCIA, and Small Form Factor Flash Card.
Flash
Memory
Flash memory is a non-volatile memory device that retains
its data after the power is removed.
Front
Side Bus
The main highway for data in a PC. It connects the processor,
chip set, DRAM, and AGP socket. FSB is described in terms
of its width in bits and its speed in MHz.
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G
Gigabit
Amount of memory equal to 1024 Megabits (1,073,741,824
bits) of information. Abbreviated Gb.
Gigabyte
Amount of memory equal to 1024 Megabytes (1,073,741,824
bytes) of information. Abbreviated GB.
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H
HPM
Hyper page mode, also known as EDO.
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I
I/O Port
Connection to a CPU that provides a data path between
the CPU and external devices, such as a keyboard, display,
or reader. It may provide input only, output only, or
both input and output.
IC
Integrated circuit. A tiny complex of electronic components
and their connections that is produced in or on a small
slice of material (such as silicon).
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J
JEDEC
Joint Electron Device Engineering Council. The group that
establishes the industry standards for memory operation,
features, and packaging.
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K
Keys
Notches on a memory module that help prevent it from being
installed incorrectly or into an incompatible system.
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L
L1 Cache
Level 1 cache. A small cache integrated in a processor
that provides quick access to the most recently used data.
L2
Cache
Level 2 cache. L2 cache has the same purpose as L1 cache,
but is usually not integrated into the processor. L2 cache
is traditionally made of SRAM and in socket 7 and older
motherboards was in some cases upgradeable. See COAST.
Latency
(also called CAS Latency)
The amount of time in nanoseconds (often measured in clock
cycles) between a request to read the memory, and when
it is actually output. SDRAMs are typically referred to
as CL2 or CL3, with CL2 parts being faster.
Lead
The official name for the metal "feet" on an
IC. Also called "pins." The part of the lead
assembly that is formed after a portion of the lead frame
is cut away. The chip's connection to the outside world.
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M
MHz
See Megahertz
MIPS
Millions of instructions per second. This measurement
is generally used when describing the speed of computer
systems.
MTBF
Mean time between failures.
MU
Memory unit. Usually a printed circuit board assembly
populated with memory chips that stores a certain quantity
of memory. Intel term for one of the types of cards in
a memory system card set.
Megabit
Amount of memory equal to 1,048,576 bits of information.
(Abbreviated Mb.)
Megabyte
Amount of memory equal to 1,048,576 bytes of information.
(Abbreviated MB.)
Megahertz
A measurement of clock cycles in millions of cycles per
second.
Memory
Configuration
The amount of memory in an IC and how it is accessed.
Memory
Cycle Time
Minimum amount of time required for a memory to complete
a cycle such as read, write, read/write, or read/modify/write.
Memory
Controller
The logic chip used to handle the I/O (input/output) of
data going to and from memory. See Chipset.
Memory
Types
Cache: static random access memory containing recently
used information
DRAM: dynamic random access memory.
SDRAM: single data rate synchronous dynamic random access
memory.
DDR SDRAM: double data rate synchronous dynamic random
access memory. Usually referred to as DDR.
SLDRAM: synchronous link dynamic random access memory.
RDRAM: Rambus dynamic random access memory.
RAM: random access memory.
ROM: read only memory (permanent memory that cannot be
changed).
SRAM: static random access memory.
Micron
1. A unit of measure equivalent to one-millionth of a
meter; synonymous with micrometer.
2. Also the company name of one of the largest memory
producers in the world and the parent company of Crucial
Technology.
Motherboard
The main printed circuit board in a computer that carries
the system buses. It is equipped with sockets to which
all processors, memory modules, plug-in cards, daughterboards,
or peripheral devices are connected.
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N
NAND
Flash Memory Chip. NAND Flash Memory Chips are the type
used in thumbdrives, flash memory cards and MP3 Players.
NAND flash memory chips are built into these USB memory
products on which consumers store images, video and music
and this chip holds data within the memory after no power
has not been applied. These products are all available
with Gigabyte capacity.
NAND Flash is a sequential access device appropriate for
mass storage applications, while NOR Flash is a random
access device appropriate for code storage applications.
NAND technology organizes cells serially to achieve higher
densities. This reduces the number of contacts needed
in the memory array. The trade-off NOR and NAND technologies
is NAND Flash data must be accessed sequentially compared
with NOR Flash which offers fast random access.
Nanometer
(nm)
One billionth of a meter.
Nanosecond(ns)
One billionth of a second; used to measure the speed of
the parts
NOR
Flash Memory Chip
Flash Memory Chip. NOR chips require power to hold the
data in the memory.
Nibble
Usually 4 bits (half a byte).
Nonvolatile
Memory
A memory that retains information if power is removed
and then reapplied. SRAM and flash are examples of nonvolatile
memory
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O
Operating system
Software controlling the overall operation of a multipurpose
computer system, including such tasks as memory allocation,
input and output distribution, interrupt processing, and
job scheduling.
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P
PCB
Printed circuit board. Board that contains layers of circuitry
that is used to connect components to a system.
PC100
The PC100 specification defines the requirements for SDRAM
modules used on 100MHz FSB motherboards.
PC133
The PC133 specification details the requirements for SDRAM
modules used on 133MHz FSB motherboards. PC133 SDRAM can
be used on 100MHz FSB motherboards but will not yield
a performance advantage over PC100 memory at 100MHz.
PCMCIA
Personal Computer Memory Card International Association.
An industry organization that helps to set standards for
flash cards.
PD
See Presence Detect.
Page
The number of bits that can be accessed from one row address.
This is also sometimes referred to as a row.
Page
Mode
Mode in which if RAS is kept low and the DRAM is given
a column address without being given a new row-address,
the chip will remember which row it was on the last time
and automatically stay on that row. It is like saying
that all the bits along one row are all on the same page,
and the part will assume the same page is intended until
a different page is specified.
Parity
A bit added to a group of bits to detect the presence
of an error. The parity bit looks at the other 8 bits
and determines if they are even or odd and correspondingly
is a 0 or 1. The system compares the 8 bits with the parity
bit. If they both are even or odd, the data is assumed
to be correct. If one is even and one is odd, there is
an error, and typically the system will fail.
Passive
Device
A device incapable of current gain or switching, such
as a resistor or capacitor.
Pin
1. The metal extensions from an IC package or discrete
component that connects the component to the PCB.
2. Another term for the Edge Contacts on a Memory Module
Populated
Board
A PCB with components.
Power
Down
To turn the system's power OFF.
Power
up
To turn the system's power ON.
Presence
Detect
Circuitry on certain memory modules that provides information
to the system.
Processor
The primary chip of the system that oversees all the other
components of the system.
Pull-up
A device or method used to keep the output voltage of
a device at a high level, often a resistor network connected
to a positive supply voltage.
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Q
Quad Flat Pack (QFP)
A flat, rectangular, integrated circuit with its leads
projecting from all four sides of the package without
radius.
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R
RAM
Random access memory. A data storage device for which
the order of access to different locations does not affect
the speed of access, except for bursts. Data is typically
stored in RAM temporarily for use by the process or while
the computer is operating. FPM, EDO, SDRAM, DDR, etc.
are all types of RAM.
RAS
Row address strobe. The signal that tells the DRAM to
accept the given address as a row address. Used with CAS
and a column address to select a bit within the DRAM.
RDRAM
Rambus DRAM is a revolutionary type of DRAM that uses
a 16-18 bit data path and is designed to operate with
FSB speed of 800MHz, producing a burst transfer rate of
1.6 gigahertz.
RIMMTM
Rambus inline memory modules used for Rambus DRAM.
Read
Time
The amount of time required for the output data to become
valid once the read and address inputs have been enabled.
Generally called access time.
Refresh
The process used to restore the charge in DRAM cells at
specific intervals.
Refresh
Rate
A count of the number of rows (in thousands) refreshed
at a time in a refresh cycle. Common refresh rates are
1K, 2K, 4K, and 8K.
Registered
Memory
Registers delay memory information for one clock cycle
to ensure all communication from the chipset is collected
by the clock edge, providing a controlled delay on heavily
loaded memories.
Row
Part of the RAM array; a bit can be stored where a column
and a row intersect. Sometimes also referred to as a page.
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S
SDR
See SDRAM
SDRAM
Synchronous dynamic random access memory delivers bursts
of data at high speeds using a synchronous interface.
Its is actually SDR SDRAM (single data rate SDRAM) but
is usually used to referred to as just "SDRAM."
SGRAM
Synchronous graphics RAM. A single port DRAM designed
for graphics hardware that requires high-speed throughput
such as 3-D rendering and full-motion video.
SIM
Single inline module. Same as SIP except with a connector
edge instead of leads.
SIMM
Single inline memory module. A high-density DRAM package
alternative consisting of several components connected
to a single printed circuit board.
SIP
Single inline package. A component or module that has
one row of leads along one side.
SLDRAM
Synchronous link dynamic random access memory. SLDRAM
is a type of SDRAM that uses a multiplexed command bus
allowing fewer pins to increase bandwidth and allow higher
FSB speeds.
SODIMM
Small outline dual inline memory module. Smaller and thinner
than standard DIMMs, SODIMMs are typically used in laptop
computers.
SORIMMTM
Small outline Rambus inline memory module. SORIMMs have
a smaller profile that standard RIMMs and are used in
laptop computers and systems that have strict size requirements.
SOJ
Small outline J-lead package. A rectangular package with
leads sticking out of the side of the package. The leads
are formed in a J-bend profile, bending underneath and
towards the bottom of the package.
SPD
Serial presence detect
SRAM
See static random access memory
Serial
Presence Detect
An EEPROM on certain memory modules used to store and
provide information to the system using the module.
Semiconductor
An element, such as silicon, that is intermediate in electrical
conductivity between conductors and insulators, through
which conduction takes place by means of holes and electrons.
Shrink
A reduction in die (chip) size. A reduction in the size
of the circuit design resulting in smaller die sizes that
increases the number of possible die per wafer.
Single
Banked
A memory module with only one bank or row. See Bank.
Speed
The time it takes to put information into memory or get
information out of memory. It is measured from the time
that an address and proper control signals are given,
until the information is stored or placed in the device's
output(s). RAM speed is typically expressed in nanoseconds
(lower is faster) for EDO and FPM, and in MHz (higher
is faster) for SDR SDRAM, DDR, SDRAM, and RDRAM.
Static
Random Access Memory
An integrated circuit similar to a DRAM (dynamic random
access memory) with the exception that the memory does
not need to be refreshed. Unlike volatile memory (ie,
DRAM), SRAM retains its contents even when the main current
is turned off.
Synchronous
Memory
Memory that has its signals synchronized with the system
clock. SDRAM and DDR are examples of synchronous memory
types.
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T
TAG
TAG memory acts as an index for the information stored
in L2 cache. It is usually composed of SRAM.
TSOP
Thin small outline package. It is thinner and slightly
smaller than an SOJ, with gullwing-shaped leads. A thin,
rectangular package with leads sticking out the sides
of the package.
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U
Unbuffered memory
This is where the chip set controller deals directly with
the memory. There is nothing between the chip set and
the memory chips on the module as they communicate.
mm
A micron (or micrometer). A unit of length equal to one
millionth of a meter.
ms
A microsecond: One millionth of a second.
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V
VCM
See Virtual Channel Memory.
VRAM
Video RAM. DRAM with an on-board serial register/serial
access memory designed for video applications.
Virtual
Channel Memory
A memory architecture that is a variant of SDRAM, that
has not been seen widespread adaptation.
Virtual
Memory
This is system memory that is simulated by the hard drive.
When all the RAM is being used (for example if there are
many programs open at the same time) the computer will
swap data to the hard drive and back to give the impression
that there is slightly more memory.
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W
Write time
Time expended from the moment data is entered for storage
to the time it is actually stored in the memory cell.
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X
Xmultiple
Technologies - Parent company of FlashPoint ShareDrives
Y
Z