Glossary of Memory (RAM) Terms
Posted March 17th, 2007 by admin
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
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.
ATA Flash Card
A PC Card suitable for data storage in portable devices. ATA Flash Cards are similar to hard disk drives.
Auto Precharge
A synchronous DRAM feature that allows the memory chip's circuitry to close a page automatically at the end of a burst.
Backside Bus
(BSB) – The data path that runs between the CPU and L2 cache.
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.
Bank Schema
A method of diagramming memory configurations. The bank schema consists of rows and/or columns that represent memory sockets on a computer board. Rows indicate independent sockets; columns represent banks.
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
(Ball Grid Array) – A chip package having solder balls on the underside for mounting. BGA allows for a reduction in die package size, better heat dissipation and greater module densities.
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.
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.
Burst EDO RAM
(BEDO) – EDO memory that can process four memory addresses in one burst. Bus speeds range from 50MHz to 66MHz (compared to 33MHz for EDO and 25MHz for Fast Page Mode).
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.)
Burst Mode
High-speed transmission of a block of data (a series of consecutive addresses) when the processor requests a single address.
Bus
A data path in a computer, consisting of various parallel wires to which the CPU, memory and all input/output devices are connected.
Bus Cycle
A single transaction between main memory and the CPU.
Byte
Eight bits of information. The byte is the fundamental unit of computer processing; almost all specifications and measures of computer performance are in bytes or multiples thereof.
Cache Memory
A small amount (normally less than 1MB) of high-speed memory residing on or close to the CPU. Cache memory supplies the processor with the most frequently requested data and instructions. Level 1 cache (primary cache) is the cache closest to the processor. Level 2 cache (secondary cache) is the cache second closest to the processor and is usually on the motherboard.
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 Latency
The ratio between column access time and clock cycle time. CAS Latency 2 (CL2) offers a slight performance increase over CAS Latency 3 (CL3).
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.
ccNUMA
(Cache-Coherent, Non-uniform Memory Access) – A flexible architecture that uses modular, low-cost components and offers multidimensional scaling potential to high-end servers.\
Chip Kill
An IBM error checking technology which protects the system from a single memory chip failure as well as any number of multiple-bit errors from any portion of a single memory chip.
Chip-Scale Package
(CSP) – Thin chip packaging whereby electrical connections are typically attached through a ball grid array. Chip-scale packaging is used in RDRAM and flash memory.
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-RIMM
Continuity RIMM Modules that are used to fill all unused RIMM 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.
CSP
Chip Scale Package. A type of ball grid array in which the package is roughly the size of the die.
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 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.
Composite
An Apple Computer, Inc. term for a memory module that used an older technology and contained more but lower-density chips.
Concurrent Rambus
The second generation of Rambus technology. Concurrent Rambus has been used in graphics-based computers, digital TVs and video game applications (such as Nintendo 64 since 1997).
Continuity RIMM
(C-RIMM) – A Direct Rambus memory module that does not contain memory chips. C-RIMM provides a continuous channel for the signal. In a Direct Rambus system, open connectors must be populated with C-RIMMs.
Controller
One of the major units in a computer that interprets and carries out the instructions in a program.
Credit Card Memory
A type of memory typically in laptop and notebook computers. Credit card memory is the size of a credit card.
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.
DDR SDRAM
(Double Data Rate Synchronous Dynamic Random-Access Memory) The latest generation of SDRAM technology. Data is read on both the rising and the falling edge of the computer clock, thereby delivering twice the bandwidth of standard SDRAM. With DDR SDRAM, memory speed doubles without increasing the clock frequency.
DIMM
(Dual In-line Memory Module) A printed circuit board with gold contacts and memory devices. A DIMM is similar to a SIMM, but with this primary difference: unlike the metal leads on either side of a SIMM, which are “tied together” electrically, the leads on either side of a DIMM are electrically independent.
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.
DIP
(Dual In-line Package) – A DRAM component packaging. DIPs can be installed in sockets or permanently soldered into holes on the printed circuit board. The DIP package was extremely popular when memory was installed directly on the motherboard.
Direct Rambus
Rambus technology’s third generation, which offers a completely new DRAM architecture for high-performance PCs. Data transfers at speeds up to 800MHz over a narrow 16-bit channel, compared to current SDRAM, which operates at 100MHz on a wide 64-bit bus.
Dual Banked
A memory module with two banks or rows.
Dual Independent Bus (DIB)
An Intel-developed bus architecture that offers greater bandwidth by having two separate buses (frontside and backside) access the processor. Pentium II computers have DIBs.
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."
ECC
(Error Correction Code) – A method of checking the integrity of data in DRAM. ECC provides more elaborate error detection than parity; ECC can detect multiple-bit errors and can locate and correct single-bit errors.
EDO
(Extended Data-Out) – A DRAM technology that shortens the read cycle between memory and CPU. On computers that support it, EDO memory allows a CPU to access memory 10 to 20 percent faster than comparable fast-page mode memory.
EDRAM (Enhanced DRAM)
Enhanced Memory Systems, Inc. DRAM that contains a small amount of SRAM.
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 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.
EOS (ECC on SIMM)
An IBM data-integrity-checking technology that features ECC data-integrity-checking on a SIMM.
ESDRAM (Enhanced Synchronous DRAM
A type of SDRAM developed by Enhanced Memory Systems, Inc. ESDRAM replaces expensive SRAM in embedded systems and offers comparable speed with less power consumption and lower cost.
Even Parity
A type of data integrity checking whereby the parity bit checks for an even number of 1s.
Fast-Cycle RAM (FCRAM)
FCRAM is a memory technology currently being developed by Toshiba and Fujitsu. FCRAM is not intended for PC main memory but will be used in specialty applications such as high-end servers, printers, and telecommunications switching systems.
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.
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.
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.
Heat Spreader
A sheath, usually aluminum, that covers an electronic device and dissipates heat.
Heat Sink
A component, typically zinc alloy, that dissipates heat. CPUs require heat sinks.
HPM
Hyper page mode, also known as EDO.
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) An electronic circuit on a semiconductor chip. The circuit includes components and connectors. A semiconductor chip is usually molded in a plastic or ceramic case and has external connector pins.
Interleaving
Techniques for increasing memory speed. For example, with separate memory banks for odd and even addresses, the next byte of memory can be accessed while the current byte refreshes.
JEDEC
Joint Electron Device Engineering Council. The group that establishes the industry standards for memory operation, features, and packaging.
Keys
Notches on a memory module that help prevent it from being installed incorrectly or into an incompatible system.
L1 Cache
Level 1 cache. Also known as primary cache, L1 Cache is a small amount of high-speed memory that resides on or very close to the processor. L1 Cache supplies the processor with the most frequently requested data and instructions.
L2 Cache
Level 2 cache. Also known as secondary cache, L2 Cache is a small amount of high-speed memory close to the CPU and usually on the motherboard. L2 Cache supplies the processor with the most frequently requested data and instructions.
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.
Linear Flash Card
A PC Card suitable for code storage in routers, notebooks, PDAs, digital cameras and other devices.
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 Bank
A logical unit of memory in a computer, the size of which the CPU determines. For example, a 32-bit CPU requires memory banks that provide 32 bits of information at a time. A bank can consist of one or more memory modules.
Memory Bus
The bus that runs from the CPU to the memory expansion slots.
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.
Memory Controller Hub (MCH)
The interface between the processor, Accelerated Graphics Port and RDRAM on motherboards that use Intel’s 820 or 840 chipsets.
Memory Translator Hub (MTH)
The interface that allows SDRAM memory to be supported on a Direct
Rambus Channel for motherboards using Intel’s 820 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.
Micro BGA (µBGA)
Tessera, Inc. BGA chip packaging technique allows for a reduction in die package size, improved heat dissipation and greater module densities.
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.
Miniature Card
A small, low-cost, Linear Flash memory card designed for memory expansion, voice/image data storage and voice/Email storage and retrieval. Miniature Cards are used in handheld devices, digital cameras, digital audio recorders and smart phones.
MMC (MultiMediaCard)
A “postage stamp”-size flash memory card which is able to store large amounts of multimedia data (i.e. music, images, speech, video, text, etc.). MMC cards are often used in digital audio players, PDAs and other portable electronic devices.
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.
Nanometer (nm)
One billionth of a meter.
Nanosecond(ns)
One billionth of a second; used to measure the speed of the parts
Nibble
Usually 4 bits (half a byte).
Non-Composite
An Apple Computer, Inc. term for a memory module that used a new technology and contained fewer but higher-density chips. Non-composite modules were more reliable and more expensive than composite modules.
Nonvolatile Memory
A memory that retains information if power is removed and then reapplied. SRAM and flash are examples of nonvolatile memory.
Odd Parity
Data integrity checking in which the parity bit checks for an odd number of 1s.
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.
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
Pipeline Burst Cache
Cache that reduces wait states and accelerates memory access by using pipelining and bursting functions.
Pipelining
A technique in which memory loads the requested memory contents into a small cache composed of SRAM, then immediately begins fetching the next memory contents. This creates a two-stage pipeline, where data is read from or written to SRAM in one stage, and data is read from or written to memory in the other stage.
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.
Proprietary Memory
Memory custom designed for a specific computer.
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.
Quad Flat Pack (QFP)
A flat, rectangular, integrated circuit with its leads projecting from all four sides of the package without radius.
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.
RIMM
Rambus inline memory modules used for Rambus DRAM.
Rambus
(1) Rambus, Inc. develops and licenses high-performance memory logic and circuit design technology and provides licensees with product design, layout and testing information.
(2) Direct Rambus is a high-speed memory technology that uses a narrow 16-bit bus (Rambus channel) to transmit data at speeds up to 800MHz. See Rambus Channel.
Rambus Channel
The data path of Rambus systems. Because of the narrow data width (two bytes), Rambus modules transfer data at up to 800MHz.
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. Refreshing maintains data stored in DRAM. The process of refreshing electrical cells on a DRAM component is similar to recharging batteries. Different DRAM components require different refresh methods.
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
SDRAM memory that contains registers directly on the module. The registers re-drive the signals through the memory chips and allow the module to be built with more memory chips. Registered and unbuffered memory cannot be mixed. The design of the computer memory controller dictates which type of memory the computer requires.
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.
SD (Secure Digital) Card
A small, high capacity, high-security flash memory card created by Matsushita Electric (Panasonic), SanDisk, and Toshiba. It provides data storage and I/O access in a variety of electronic devices.
SDRAM
(Synchronous DRAM) A DRAM technology that uses a clock to synchronize signal input and output on a memory chip. The clock is coordinated with the CPU clock so the timing of the memory chips and the timing of the CPU are in synch. Synchronous DRAM saves time in executing commands and transmitting data, thereby increasing the overall performance of the computer.
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.
SORIMM
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.
SRAM
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.
Self-Refresh
A memory technology that enables DRAM to refresh on its own and independent of the CPU or external refresh circuitry. Self-Refresh technology is built into the DRAM chip itself and reduces power consumption dramatically. Notebook and laptop computers use this technology.
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. .
SmartMedia (SSFDC)
Very thin flash memory card used for data storage in digital cameras, PDAs, digital audio recorders and other portable devices.
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.
Swapping
Using part of the hard drive as memory when RAM is full. See Virtual Memory.
Synchronous Memory
Memory that has its signals synchronized with the system clock. SDRAM and DDR are examples of synchronous memory types.
TAG
TAG memory acts as an index for the information stored in L2 cache. It is usually composed of SRAM.
Transmission Line Technology
A technology that supports the backside bus in Direct Rambus systems.Information is quickly pipelined in simultaneous packets. The memory controller reassembles the packets for frontside bus transfer and communication to the processor.
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.
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.
VCM
(Virtual Channel Memory). A memory architecture that is a variant of SDRAM, that has not been seen widespread adaptation.
VRAM
(Video Random-Access Memory) Dual-ported (two separate data ports) memory typically on a video or graphics card. One port is dedicated to the CRT and refreshes and updates the image. The second port is for the CPU or graphics controller and changes the image data in memory.
Virtual Channel Memory
VCM is a memory architecture developed by NEC. VCM allows different blocks of memory–each with its own buffer–to interface separately with the controller. This way, system tasks can be assigned their own virtual channels. Information related to one function does not share buffer space with other tasks running simultaneously, thereby making overall operations much more efficient.
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.
Wait State
An inactive period for the processor. Wait states result from the different clock speeds of the processor and memory, the latter being typically slower.
Window Random Acces Memory
(WRAM) Samsung Electronics’ dual-ported (two separate data ports) memory typically on a video or graphics card. WRAM has a 25% higher bandwidth than VRAM but costs less.
Write time
Time expended from the moment data is entered for storage to the time it is actually stored in the memory cell.