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Computer memory and data storage types
General Memory cell Memory coherence Cache coherence Memory hierarchy Memory access pattern Memory map Secondary storage MOS memory floating-gate Continuous availability Areal density (computer storage) Block (data storage) Object storage Direct-attached storage Network-attached storage Storage area network Block-level storage Single-instance storage Data Structured data Unstructured data Big data Metadata Data compression Data corruption Data cleansing Data degradation Data integrity Data security Data validation Data validation and reconciliation Data recovery Storage Data cluster Directory Shared resource File sharing File system Clustered file system Distributed file system Distributed file system for cloud Distributed data store Distributed database Database Data bank Data storage Data store Data deduplication Data structure Data redundancy Replication (computing) Memory refresh Storage record Information repository Knowledge base Computer file Object file File deletion File copying Backup Core dump Hex dump Data communication Information transfer Temporary file Copy protection Digital rights management Volume (computing) Boot sector Master boot record Volume boot record Disk array Disk image Disk mirroring Disk aggregation Disk partitioning Memory segmentation Locality of reference Logical disk Storage virtualization Virtual memory Memory-mapped file Software entropy Software rot In-memory database In-memory processing Persistence (computer science) Persistent data structure RAID Non-RAID drive architectures Memory paging Bank switching Grid computing Cloud computing Cloud storage Fog computing Edge computing Dew computing Amdahl's law Moore's law Kryder's law
Volatile
RAM Hardware cache CPU cache Scratchpad memory DRAM eDRAM SDRAM SGRAM LPDDR QDRSRAM EDO DRAM XDR DRAM RDRAM DDR GDDR HBM SRAM 1T-SRAM ReRAM QRAM Content-addressable memory (CAM) Computational RAM VRAM Dual-ported RAM Video RAM (dual-ported DRAM)
Historical Williams–Kilburn tube (1946–1947) Delay-line memory (1947) Mellon optical memory (1951) Selectron tube (1952) Dekatron T-RAM (2009) Z-RAM (2002–2010)
Non-volatile
ROM Diode matrix MROM PROM EPROM EEPROM ROM cartridge Solid-state storage (SSS) Flash memory is used in: Solid-state drive (SSD) Solid-state hybrid drive (SSHD) USB flash drive IBM FlashSystem Flash Core Module Memory card Memory Stick CompactFlash PC Card MultiMediaCard SD card SIM card SmartMedia Universal Flash Storage SxS MicroP2 XQD card Programmable metallization cell
NVRAM Memistor Memristor PCM (3D XPoint) MRAM Electrochemical RAM (ECRAM) Nano-RAM CBRAM
Early-stage NVRAM FeRAM ReRAM FeFET memory
Analog recording Phonograph cylinder Phonograph record Quadruplex videotape Vision Electronic Recording Apparatus Magnetic recording Magnetic storage Magnetic tape Magnetic-tape data storage Tape drive Tape library Digital Data Storage (DDS) Videotape Videocassette Cassette tape Linear Tape-Open Betamax 8 mm video format DV MiniDV MicroMV U-matic VHS S-VHS VHS-C D-VHS Hard disk drive
Optical 3D optical data storage Optical disc LaserDisc Compact Disc Digital Audio (CDDA) CD CD Video CD-R CD-RW Video CD Super Video CD Mini CD Nintendo optical discs CD-ROM Hyper CD-ROM DVD DVD+R DVD-Video DVD card DVD-RAM MiniDVD HD DVD Blu-ray Ultra HD Blu-ray Holographic Versatile Disc WORM
In development CBRAM Racetrack memory NRAM Millipede memory ECRAM Patterned media Holographic data storage Electronic quantum holography 5D optical data storage DNA digital data storage Universal memory Time crystal Quantum memory UltraRAM
Historical Paper data storage (1725) Punched card (1725) Punched tape (1725) Plugboard Drum memory (1932) Magnetic-core memory (1949) Plated-wire memory (1957) Core rope memory (1960s) Thin-film memory (1962) Disk pack (1962) Twistor memory (~1968) Bubble memory (~1970) Floppy disk (1971)
v t e

Volatile memory, in contrast to non-volatile memory, is computer memory that requires power to maintain the stored information; it retains its contents while powered on but when the power is interrupted, the stored data is quickly lost.

Volatile memory has several uses including as primary storage. In addition to usually being faster than forms of mass storage such as a hard disk drive, volatility can protect sensitive information, as it becomes unavailable on power-down. Most general-purpose random-access memory (RAM) is volatile.

Types

There are two kinds of volatile RAM: dynamic and static. Even though both types need continuous electrical current to retain data, there are some important differences between them.

Dynamic RAM (DRAM) is very popular due to its cost-effectiveness. DRAM stores each bit of information in a different capacitor within the integrated circuit. DRAM chips need just one single capacitor and one transistor to store each bit of information. This makes it space-efficient and inexpensive.

The main advantage of static RAM (SRAM) is that it is much faster than dynamic RAM. Its disadvantage is its high price. SRAM does not need continuous electrical refreshes, but it still requires constant current to sustain the difference in voltage. Every single bit in a static RAM chip needs a cell of six transistors, whereas dynamic RAM requires only one capacitor and one transistor. As a result, SRAM is unable to accomplish the storage capabilities of the DRAM family. SRAM is commonly used as CPU cache and for processor registers and in networking devices.

References

"What is volatile memory? - Definition from WhatIs.com". WhatIs.com.
DRAM Technology (PDF), Integrated Circuit Engineering Corporation, retrieved 2018-03-27
"What is the difference between static RAM and dynamic RAM?". HowStuffWorks. 2000-08-24. Retrieved 2018-05-14.

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Computer memory