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Encyclopedia > Computer storage
1 GiB of SDRAM mounted in a personal computer
1 GiB of SDRAM mounted in a personal computer

Computer storage, computer memory, and often casually memory refer to computer components, devices and recording media that retain digital data used for computing for some interval of time. Computer storage provides one of the core functions of the modern computer, that of information retention. It is one of the fundamental components of all modern computers, and coupled with a central processing unit (CPU), implements the basic Von Neumann computer model used since the 1940s. Image File history File links Download high-resolution version (1600x1067, 614 KB) DDR2 Ram in socket File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Computer storage ... Image File history File links Download high-resolution version (1600x1067, 614 KB) DDR2 Ram in socket File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Computer storage ... A gibibyte is a unit of information or computer storage. ... This article or section does not cite any references or sources. ... The NASA Columbia Supercomputer. ... A recording medium is a physical material that holds information expressed in any of the existing recording formats. ... In Computer Science, data is often distinguished from code, though both are represented in modern computers as binary strings. ... Die of an Intel 80486DX2 microprocessor (actual size: 12×6. ... Design of the Von Neumann architecture For the robotic architecture also named after Von Neumann, see Von Neumann machine The von Neumann architecture is a computer design model that uses a single storage structure to hold both instructions and data. ...


In contemporary usage, memory usually refers to a form of solid state storage known as random access memory (RAM) and sometimes other forms of fast but temporary storage. Similarly, storage more commonly refers to mass storage - optical discs, forms of magnetic storage like hard disks, and other types of storage which are slower than RAM, but of a more permanent nature. These contemporary distinctions are helpful, because they are also fundamental to the architecture of computers in general. As well, they reflect an important and significant technical difference between memory and mass storage devices, which has been blurred by the historical usage of the terms "main storage" (and sometimes "primary storage") for random access memory, and "secondary storage" for mass storage devices. This is explained in the following sections, in which the traditional "storage" terms are used as sub-headings for convenience. In electronics, solid state circuits are those that do not contain vacuum tubes. ... Random access memory (usually known by its acronym, RAM) is a type of data storage used in computers. ... In computing, mass storage refers to storage of large amounts of information in a persisting and machine-readable fashion. ... The optical lens of a compact disc drive. ... Magnetic storage is a term from engineering referring to the storage of data on a magnetised medium. ... Typical hard drives of the mid-1990s. ...

Contents

Purposes of storage

The fundamental components of a general-purpose computer are arithmetic and logic unit, control circuitry, storage space, and input/output devices. If storage is removed, a computer can only function as a digital signal processing device (e.g. calculator, media player). The ability to store instructions that form a computer program, and the information that the instructions manipulate, is what makes stored program architecture computers versatile enough for general purposes. ALU redirects here. ... A control unit is the part of a CPU or other device that directs its operation. ... Digital signal processing (DSP) is the study of signals in a digital representation and the processing methods of these signals. ... A calculator is a device for performing calculations. ... This article is about media players in general. ... In computer science, an instruction typically refers to a single operation of a processor within a computer architecture. ... Design of the Von Neumann architecture For the robotic architecture also named after Von Neumann, see Von Neumann machine The von Neumann architecture is a computer design model that uses a single storage structure to hold both instructions and data. ...


A digital computer represents information using the binary numeral system. Text, numbers, pictures, audio, and nearly any other form of information can be converted into a string of bits, or binary digits, each of which has a value of 1 or 0. The most common unit of storage is the byte, equal to 8 bits. A piece of information can be manipulated by any computer whose storage space is large enough to accommodate the corresponding data, or the binary representation of the piece of information. For example, a computer with a storage space of eight million bits, or one megabyte, could be used to edit a small novel. ... The binary numeral system, or base-2 number system, is a numeral system that represents numeric values using two symbols, usually 0 and 1. ... This article is about the unit of information. ... In computer science a byte (pronounced bite) is a unit of measurement of information storage, most often consisting of eight bits. ... In Computer Science, data is often distinguished from code, though both are represented in modern computers as binary strings. ... ReBoot character, see Megabyte (ReBoot). ... A novel (from French nouvelle Italian novella, new) is an extended, generally fictional narrative, typically in prose. ...

Various forms of storage, divided according to their distance from the central processing unit. Additionally, common technology and capacity found in home computers of 2005 is indicated next to some items.
Various forms of storage, divided according to their distance from the central processing unit. Additionally, common technology and capacity found in home computers of 2005 is indicated next to some items.

Various forms of storage, based on various natural phenomena, have been invented. So far, no practical universal storage medium exists, and all forms of storage have some drawbacks. Therefore a computer system usually contains several kinds of storage, each with an individual purpose, as shown in the diagram. Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Die of an Intel 80486DX2 microprocessor (actual size: 12×6. ... The home computer is a consumer-friendly word for the second generation of microcomputers (the technical term that was previously used), entering the market in 1977 and becoming common during the 1980s. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ...

Primary storage

Primary storage is directly connected to the central processing unit of the computer. It must be present for the CPU to function correctly. As shown in the diagram, primary storage typically consists of three kinds of storage: Primary storage, or internal memory, is computer memory that is accessible to the central processing unit of a computer without the use of computers input/output channels. ... Die of an Intel 80486DX2 microprocessor (actual size: 12×6. ...

  • Processor registers are internal to the central processing unit. Registers contain information that the arithmetic and logic unit needs to carry out the current instruction. They are technically the fastest of all forms of computer storage, being switching transistors integrated on the CPU's silicon chip, and functioning as electronic "flip-flops".
  • Cache memory is a special type of internal memory used by many central processing units to increase their performance or "throughput". Some of the information in the main memory is duplicated in the cache memory, which is slightly slower but of much greater capacity than the processor registers, and faster but much smaller than main memory. Multi-level cache memory is also commonly used—"primary cache" being smallest, fastest and closest to the processing device; "secondary cache" being larger and slower, but still faster and much smaller than main memory.
  • Main memory contains the programs that are currently being run and the data the programs are operating on. In modern computers, the main memory is the electronic solid-state random access memory. It is directly connected to the CPU via a "memory bus" (shown in the diagram) and a "data bus". The arithmetic and logic unit can very quickly transfer information between a processor register and locations in main storage, also known as a "memory addresses". The memory bus is also called an address bus or front side bus and both busses are high-speed digital "superhighways". Access methods and speed are two of the fundamental technical differences between memory and mass storage devices. (Note that all memory sizes and storage capacities shown in the diagram will inevitably be exceeded with advances in technology over time.)

In computer architecture, a processor register is a small amount of very fast computer memory used to speed the execution of computer programs by providing quick access to commonly used values—typically, the values being in the midst of a calculation at a given point in time. ... An integrated circuit (IC) is a thin chip consisting of at least two interconnected semiconductor devices, mainly transistors, as well as passive components like resistors. ... This article is about the computer term. ... Primary storage is a category of computer storage, often called main memory. ... Random access memory (usually known by its acronym, RAM) is a type of data storage used in computers. ... In a computer, main storage is a program-addressable storage from which instructions and other data may be loaded directly into registers for subsequent execution or processing. ... An address bus is (part of) a computer bus, used by CPUs or DMA-capable units for communicating the physical addresses of computer memory elements/locations that the requesting unit wants to access (read/write). ... In computers, the front side bus (FSB) or system bus is the physical bi-directional data bus that carries all electronic signal information between the central processing unit (CPU) and the northbridge. ...

Secondary and off-line storage

Secondary storage requires the computer to use its input/output channels to access the information, and is used for long-term storage of persistent information. However most computer operating systems also use secondary storage devices as virtual memory - to artificially increase the apparent amount of main memory in the computer. Secondary storage is also known as "mass storage". Secondary or mass storage is typically of much greater capacity than primary storage (main memory), but it is also much slower. In modern computers, hard disks are usually used for mass storage. The time taken to access a given byte of information stored on a hard disk is typically a few thousandths of a second, or milliseconds. By contrast, the time taken to access a given byte of information stored in random access memory is measured in thousand-millionths of a second, or nanoseconds. This illustrates the very significant speed difference which distinguishes solid-state memory from rotating magnetic storage devices: hard disks are typically about a million times slower than memory. Rotating optical storage devices, such as CD and DVD drives, are typically even slower than hard disks, although their access speeds are likely to improve with advances in technology. Therefore, the use of virtual memory, which is millions of times slower than "real" memory, significantly degrades the performance of any computer. Virtual memory is implemented by many operating systems using terms like swap file or "cache file". The main historical advantage of virtual memory was that it was much less expensive than real memory. That advantage is less relevant today, yet surprisingly most operating systems continue to implement it, despite the significant performance penalties. In computer storage, secondary storage, or external memory, is computer memory that is not directly accessible to the central processing unit of a computer, requiring the use of computers input/output channels. ... Energy Input: The energy placed into a reaction. ... It has been suggested that Maintenance OS be merged into this article or section. ... How virtual memory maps to physical memory Virtual memory is an addressing scheme implemented in hardware and software that allows non-contiguous memory to be addressed as if it were contiguous. ... In computing, mass storage refers to storage of large amounts of information in a persisting and machine-readable fashion. ... Typical hard drives of the mid-1990s. ... A Compact Disc or CD is an optical disc used to store digital data, originally developed for storing digital audio. ... Size comparison: A 12 cm Sony DVD+RW and a 19 cm Dixon Ticonderoga pencil. ... Virtual memory is intended to help the programmer by taking care of some memory housekeeping duties. ...


Off-line storage is a system where the storage medium can be easily removed from the storage device. Off-line storage is used for data transfer and archival purposes. In modern computers, CDs, DVDs, memory cards, flash memory devices including "USB drives", floppy disks, Zip disks and magnetic tapes are commonly used for off-line mass storage purposes. "Hot-pluggable" USB hard disks are also available. Off-line storage devices used in the past include punched cards, microforms,drums. Off-line storage is a computer storage medium which must be inserted into a computer drive by a human operator before a computer can access the information stored on the medium. ... The movement of data from one location to another is called data transfer. ... This article does not cite any references or sources. ... A USB flash drive. ... Note: USB may also mean upper sideband in radio. ... A floppy disk is a data storage device that is composed of a disk of thin, flexible (floppy) magnetic storage medium encased in a square or rectangular plastic shell. ... Later (USB, left) and earlier (parallel, right) Zip drives (media in foreground). ... Magnetic tape has been used for data storage for over 50 years. ... A CTR census machine, utilizing a punched card system. ... A roll of microfilm Microfiche Microforms are processed films that carry images of documents to users for transmission, storage, reading and printing. ...


Tertiary and database storage

Tertiary storage is a system where a robotic arm will "mount" (connect) or "dismount" off-line mass storage media (see the previous item) according to the computer operating system's demands. Tertiary storage is used in the realms of enterprise storage and scientific computing on large computer systems and business computer networks, and is something a typical personal computer user never sees firsthand. Tertiary storage, or tertiary memory, is a computer storage system consisting of one or more computer drives and an automatic media library, for example a tape library or optical disc jukebox. ... Enterprise storage is the field of information technology focused on the storage, protection, and retrieval of data in large-scale environments. ... Scientific computing (or computational science) is the field of study concerned with constructing mathematical models and numerical solution techniques and using computers to analyze and solve scientific and engineering problems. ... “Computer Networks” redirects here. ...


Database storage is a system where information in computers is stored in large databases, data banks, data warehouses, or data vaults. It involves packing and storing large amounts of storage devices throughout a series of shelves in a room, usually an office, all linked together. The information in database storage systems can be accessed by a supercomputer, mainframe computer, or personal computer. Databases, data banks, and data warehouses, etc, can only be accessed by authorized users. This article does not cite any references or sources. ... In telecommunications, a data bank is a repository of information on one or more subjects that is organized in a way that facilitates local or remote information retrieval. ... A data warehouse is the main repository of an organizations historical data, its corporate memory. ... A supercomputer is a computer that led the world (or was close to doing so) in terms of processing capacity, particularly speed of calculation, at the time of its introduction. ... This article does not cite any references or sources. ...


Network storage

Network storage is any type of computer storage that involves accessing information over a computer network. Network storage arguably allows to centralize the information management in an organization, and to reduce the duplication of information. Network storage includes: “Computer Networks” redirects here. ... Information management is the cibai collection and lancau management of information from one or more sources and distribution to fuck one or more audiences who have a stake in that information or a right to that information. ...

  • Network-attached storage is secondary or tertiary storage attached to a computer which another computer can access at file level over a local-area network, a private wide-area network, or in the case of online file storage, over the Internet.
  • Storage area network provides other computers with storage capacity over a network, the crucial difference between network-attached storage (NAS) and storage area Networks (SAN) is the former presents and manages file systems to client computers, whilst a SAN provides access to disks at block addressing level, leaving it to attaching systems to manage data or file systems within the provided capacity.
  • Network computers are computers that do not contain internal secondary storage devices. Instead, documents and other data are stored on a network-attached storage.

Confusingly, these terms are sometimes used differently. Primary storage can be used to refer to local random-access disk storage, which should properly be called secondary storage. If this type of storage is called primary storage, then the term secondary storage would refer to offline, sequential-access storage like tape media. Samba Network Icon Network-attached storage (NAS) is the name given to dedicated data storage technology which can be connected directly to a computer network to provide centralized data access and storage to heterogeneous network clients. ... A local area network (LAN) is a computer network covering a local area, like a home, office or small group of buildings such as a college. ... A wide area network or WAN is a computer network covering a wide geographical area, involving vast array of computers. ... It has been suggested that this article or section be merged with Online backup. ... In computing, a storage area network (SAN) is an architecture to attach remote computer storage devices such as disk array controllers, tape libraries and CD arrays to servers in such a way that to the operating system the devices appear as locally attached devices. ... Samba Network Icon Network-attached storage (NAS) is the name given to dedicated data storage technology which can be connected directly to a computer network to provide centralized data access and storage to heterogeneous network clients. ... A network computer is a lightweight computer system that operates exclusively via a network connection. ...


Characteristics of storage

The division to primary, secondary, tertiary and off-line storage is based on memory hierarchy, or distance from the central processing unit. There are also other ways to characterize various types of storage. The hierarchical arrangement of storage in current computer architectures is called the memory hierarchy. ...


Volatility of information

  • Volatile memory requires constant power to maintain the stored information. Volatile memory is typically used only for primary storage. (Primary storage is not necessarily volatile, even though today's most cost-effective primary storage technologies are. Non-volatile technologies have been widely used for primary storage in the past and may again be in the future.)
  • Non-volatile memory will retain the stored information even if it is not constantly supplied with electric power. It is suitable for long-term storage of information, and therefore used for secondary, tertiary, and off-line storage.
  • Dynamic memory is volatile memory which also requires that stored information is periodically refreshed, or read and rewritten without modifications.

Volatile memory refers to computer memory that must be powered to maintain its data. ... It has been suggested that this article or section be merged with NVRAM. (Discuss) Non-volatile memory, nonvolatile memory, NVM or non-volatile storage, is computer memory that can retain the stored information even when not powered. ... Memory refresh is the process of periodically reading information from an area of computer memory, and immediately rewriting the read information to the same area with no modifications. ...

Ability to access non-contiguous information

  • Random access means that any location in storage can be accessed at any moment in the same, usually small, amount of time. This makes random access memory well suited for primary storage.
  • Sequential access means that the accessing a piece of information will take a varying amount of time, depending on which piece of information was accessed last. The device may need to seek (e.g. to position the read/write head correctly), or cycle (e.g. to wait for the correct location in a revolving medium to appear below the read/write head).

In computer science, random access is the ability to access a random element of a group in equal time. ... Random access memory (usually known by its acronym, RAM) is a type of data storage used in computers. ... In computer science sequential access means that a group of elements (e. ... Microphotograph of a hard disk head. ...

Ability to change information

  • Read/write storage, or mutable storage, allows information to be overwritten at any time. A computer without some amount of read/write storage for primary storage purposes would be useless for many tasks. Modern computers typically use read/write storage also for secondary storage.
  • Read only storage retains the information stored at the time of manufacture, and write once storage (WORM) allows the information to be written only once at some point after manufacture. These are called immutable storage. Immutable storage is used for tertiary and off-line storage. Examples include CD-R.
  • Slow write, fast read storage is read/write storage which allows information to be overwritten multiple times, but with the write operation being much slower than the read operation. Examples include CD-RW.

A worm is an elongated, slender, soft-bodied invertebrate animal. ... This article does not cite any references or sources. ... Compact Disc ReWritable (CD-RW) is a rewritable optical disc format. ...

Addressability of information

  • In location-addressable storage, each individually accessible unit of information in storage is selected with its numerical memory address. In modern computers, location-addressable storage usually limits to primary storage, accessed internally by computer programs, since location-addressability is very efficient, but burdensome for humans.
  • In file system storage, information is divided into files of variable length, and a particular file is selected with human-readable directory and file names. The underlying device is still location-addressable, but the operating system of a computer provides the file system abstraction to make the operation more understandable. In modern computers, secondary, tertiary and off-line storage use file systems.
  • In content-addressable storage, each individually accessible unit of information is selected with a hash value, or a short identifier with number? pertaining to the memory address the information is stored on. Content-addressable storage can be implemented using software (computer program) or hardware (computer device), with hardware being faster but more expensive option.

In computer science, a memory address is a unique identifier for a memory location at which a CPU or other device can store a piece of data for later retrieval. ... It has been suggested that Crash counting be merged into this article or section. ... A computer file is a collection of information that is stored in a computer system and can be identified by its full path name. ... Human-readable refers to a representation of information that can be naturally read by humans. ... It has been suggested that Maintenance OS be merged into this article or section. ... In computer science, abstraction is a mechanism and practice to reduce and factor out details so that one can focus on a few concepts at a time. ... Content-addressable memory (CAM) is a special type of computer memory used in certain very high speed searching applications. ... A hash function is a reproducible method of turning some kind of data into a (relatively) small number that may serve as a digital fingerprint of the data. ... It has been suggested that this article or section be merged with Computer program. ... Computer hardware is the physical part of a computer, including the digital circuitry, as distinguished from the computer software that executes within the hardware. ...

Capacity and performance

  • Storage capacity is the total amount of stored information that a storage device or medium can hold. It is expressed as a quantity of bits or bytes (e.g. 10.4 megabytes).
  • Storage density refers to the compactness of stored information. It is the storage capacity of a medium divided with a unit of length, area or volume (e.g. 1.2 megabytes per square inch).
  • Latency is the time it takes to access a particular location in storage. The relevant unit of measurement is typically nanosecond for primary storage, millisecond for secondary storage, and second for tertiary storage. It may make sense to separate read latency and write latency, and in case of sequential access storage, minimum, maximum and average latency.
  • Throughput is the rate at which information can be read from or written to the storage. In computer storage, throughput is usually expressed in terms of megabytes per second or MB/s, though bit rate may also be used. As with latency, read rate and write rate may need to be differentiated.

This article is about the unit of information. ... In computer science a byte (pronounced bite) is a unit of measurement of information storage, most often consisting of eight bits. ... ReBoot character, see Megabyte (ReBoot). ... Computer storage density is a measure of the quantity of information bits that can be stored on a given length of track, area of surface, or in a given volume; of a computer storage medium. ... Latency is a time delay between the moment something is initiated, and the moment one of its effects begins. ... Measurement is the determination of the size or magnitude of something. ... To help compare orders of magnitude of different times this page lists times between 10−9 seconds and 10−8 seconds (1 nanosecond and 10 nanoseconds) See also times of other orders of magnitude. ... One millisecond is one-thousandth of a second. ... Look up second in Wiktionary, the free dictionary. ... In communication networks, throughput is the amount of digital data per time unit that is delivered over a physical or logical link, or that is passing through a certain network node. ... In telecommunications and computing, bit rate (sometimes written bitrate) is the frequency at which bits are passing a given (physical or metaphorical) point. It is quantified using the bit per second (bit/s) unit. ...

Technologies, devices and media

Magnetic storage

Magnetic storage uses different patterns of magnetization on a magnetically coated surface to store information. Magnetic storage is non-volatile. The information is accessed using one or more read/write heads. Since the read/write head only covers a part of the surface, magnetic storage is sequential access and must seek, cycle or both. In modern computers, the magnetic surface will take these forms: Magnetic storage is a term from engineering referring to the storage of data on a magnetised medium. ... Magnetization is a property of some materials (e. ... In physics, magnetism is a phenomenon by which materials exert an attractive or repulsive force on other materials. ... Microphotograph of a hard disk head. ...

In early computers, magnetic storage was also used for primary storage in a form of magnetic drum, or core memory, core rope memory, thin film memory, twistor memory or bubble memory. Also unlike today, magnetic tape was often used for secondary storage. Disk storage is a group of data storage mechanisms for computers; data are transferred to planar surfaces or disks for temporary or permanent storage. ... A floppy disk is a data storage device that is composed of a disk of thin, flexible (floppy) magnetic storage medium encased in a square or rectangular plastic shell. ... Typical hard drives of the mid-1990s. ... Magnetic tape has been used for data storage for over 50 years. ... The Magnetic Drum was invented by G. Taushek in 1932 in Austria. ... A 16×16 cm area core memory plane of 128×128 bits, i. ... Core rope memory is a form of read-only memory (ROM) for computers, first used by early NASA Mars probes and then in the Apollo Guidance Computer (AGC) designed by MIT and built by Raytheon. ... Thin film memory is a high-speed variation of core memory developed by Sperry Rand in a government-funded research project. ... Twistor is a form of computer memory, similar to core memory, formed by wrapping magnetic tape around a current-carrying wire. ... Bubble memory is a type of non-volatile computer memory that uses a thin film of a magnetic material to hold small magnetized areas, known as bubbles, which each store one bit of data. ...


Semiconductor storage

Semiconductor memory uses semiconductor-based integrated circuits to store information. A semiconductor memory chip may contain millions of tiny transistors or capacitors. Both volatile and non-volatile forms of semiconductor memory exist. In modern computers, primary storage almost exclusively consists of dynamic volatile semiconductor memory or dynamic random access memory. Since the turn of the century, a type of non-volatile semiconductor memory known as flash memory has steadily gained share as off-line storage for home computers. Non-volatile semiconductor memory is also used for secondary storage in various advanced electronic devices and specialized computers. Semiconductor memory is a generic term referring to any computer storage method implemented on a semiconductor-based integrated circuit. ... A semiconductor is a fuckin solid whose electrical conductivity is in between that of a metal and that of an insulator, and can be controlled over a wide range, either permanently or dynamically. ... Integrated circuit of Atmel Diopsis 740 System on Chip showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window, showing the integrated circuit inside. ... Assorted discrete transistors A transistor is a semiconductor device, commonly used as an amplifier or an electrically controlled switch. ... Capacitors: SMD ceramic at top left; SMD tantalum at bottom left; through-hole tantalum at top right; through-hole electrolytic at bottom right. ... Dynamic random access memory (DRAM) is a type of random access memory that stores each bit of data in a separate capacitor within an integrated circuit. ... A USB flash drive. ...


Optical disc storage

Optical disc storage uses tiny pits etched on the surface of a circular disc to store information, and reads this information by illuminating the surface with a laser diode and observing the reflection. Optical disc storage is non-volatile and sequential access. The following forms are currently in common use: The optical lens of a compact disc drive. ... A packaged laser diode with penny for scale. ...

The following form have also been proposed: CD may stand for: Compact Disc Canadian Forces Decoration Cash Dispenser (at least used in Japan) CD LPMud Driver Centrum-Demokraterne (Centre Democrats of Denmark) Certificate of Deposit ÄŒeské Dráhy (Czech Railways) Chad (NATO country code) Chalmers Datorförening (computer club of the Chalmers University of Technology) a 1960s... The CD-ROM (an abbreviation for Compact Disc Read-Only Memory (ROM)) is a non-volatile optical data storage medium using the same physical format as audio compact discs, readable by a computer with a CD-ROM drive. ... Size comparison: A 12 cm Sony DVD+RW and a 19 cm Dixon Ticonderoga pencil. ... This article does not cite any references or sources. ... A DVD+R disc The title given to this article is incorrect due to technical limitations. ... This article or section does not cite any references or sources. ... Compact Disc ReWritable (CD-RW) is a rewritable optical disc format. ... The title given to this article is incorrect due to technical limitations. ... This article or section does not cite its references or sources. ... You can recognize a DVD-RAM immediately because visually there are lots of little rectangles distributed on the surface of the data carrier. ... Blu-ray discs Blu-ray Disc is a next-generation optical disc format jointly developed by a group of leading consumer electronics and PC companies called the Blu_ray Disc Association (BDA), which succeeds the Blu_ray Disc Founders (BDF). ... HD-DVD disc HD DVD (for High Density Digital Versatile Disc) is a digital optical media format which is being developed as one standard for high-definition DVD. HD DVD is similar to the competing Blu-ray Disc, which also uses the same CD sized (120 mm diameter) optical data... Ultra Density Optical (UDO) is a next-generation optical disc format designed for high-density storage of high-definition video and data. ... PDD, ProDATA or Professional Disc for DATA is a recordable optical disc format which was introduced by Sony in 2003. ...

Picture of an HVD by Optware. ... Phase-Change Dual (PD) is a rewritable optical disc format introduced by Panasonic in 1995. ... 3D Optical Data Storage is characterized by the ability to inscribe data within the volume of a data storage medium with three-dimensional resolution, as opposed to the two-dimensional resolution afforded by, for example, magnetic tape or CD. This innovation potentially allows very high data densities, but requires addressing...

Magneto-optical disc storage

Magneto-optical disc storage is optical disc storage where the magnetic state on a ferromagnetic surface stores information. The information is read optically and written by combining magnetic and optical methods. Magneto-optical disc storage is non-volatile, sequential access, slow write, fast read storage used for tertiary and off-line storage. Magneto-optical disc. ... Ferromagnetism is a phenomenon by which a material can exhibit a spontaneous magnetization, and is one of the strongest forms of magnetism. ...


Ultra Density Optical disc storage

Ultra Density Optical disc storage An Ultra Density Optical disc or UDO is a 5.25" ISO cartridge optical disc encased in a dust-proof caddy which can store up to 30 GB of data. Utilising a design based on a magneto-optical disc, but utilising phase change technology combined with a blue violet laser, a UDO disc can store substantially more data than a magneto-optical disc or MO, because of the shorter wavelength (405 nm) of the blue-violet laser employed. MOs use a 650-nm-wavelength red laser. Because its beam width is shorter when burning to a disc than a red-laser for MO, a blue-violet laser allows more information to be stored digitally in the same amount of space. Ultra Density Optical (UDO) is a next-generation optical disc format designed for high-density storage of high-definition video and data. ... Magneto-optical disc A Magneto-optical disc and the numerous rectangles on its surface A magneto-optical drive is a kind of optical disc drive capable of writing and rewriting data upon magneto-optical discs. ... In its most common usage, the term phase change indicates that a substance has changed among the three classical phases of matter: solid, liquid and gas. ... Magneto-optical disc A Magneto-optical disc and the numerous rectangles on its surface A magneto-optical drive is a kind of optical disc drive capable of writing and rewriting data upon magneto-optical discs. ... The wavelength is the distance between repeating units of a wave pattern. ... The metre (American English:meter) is a measure of length. ...


Current generations of UDO store up to 30 GB, but 60 GB and 120 GB versions of UDO are in development and are expected to arrive sometime in 2007 and beyond, though up to 500 GB has been speculated as a possibility for UDO. [1]


Optical Jukebox storage

Optical jukebox storage is a robotic storage device that utilizes optical disk device and can automatically load and unload optical disks and provide terabytes of near-line information. The devices are often called optical disk libraries, robotic drives, or autochangers. Jukebox devices may have up to 1,000 slots for disks, and usually have a picking device that traverses the slots and drives. The arrangement of the slots and picking devices affects performance, depending on the space between a disk and the picking device. Seek times and transfer rates vary depending upon the optical technology. Jukeboxes are used in high-capacity archive storage environments such as imaging, medical, and video. HSM is a strategy that moves little-used or unused files from fast magnetic storage to optical jukebox devices in a process called migration. If the files are needed, they are migrated back to magnetic disk. An optical jukebox or autochanger is a computer device used for massive data storage. ...


Other early methods

Paper tape and punch cards have been used to store information for automatic processing since the 1890s, long before general-purpose computers existed. Information was recorded by punching holes into the paper or cardboard medium, and was read by electrically (or, later, optically) sensing whether a particular location on the medium was solid or contained a hole. A roll of punched tape Punched tape is an old-fashioned form of data storage, consisting of a long strip of paper in which holes are punched to store data. ... Punched cards (or Hollerith cards, or IBM cards), are pieces of stiff paper that contain digital information represented by the presence or absence of holes in predefined positions. ... The 1890s were sometimes referred to as the Mauve Decade, because William Henry Perkins aniline dye allowed the widespread use of that colour in fashion, and also as the Gay Nineties, under the then-current usage of the word gay which referred simply to merriment and frivolity, with no...


Williams tube used a cathode ray tube, and Selectron tube used a large vacuum tube to store information. These primary storage devices were short-lived in the market, since Williams tube was unreliable and Selectron tube was expensive. The Williams tube or (more accurately) the Williams-Kilburn tube (after Freddie Williams and coworker Tom Kilburn), developed about 1946 or 1947, was a cathode ray tube used to store electronic data. ... Cathode ray tube employing electromagnetic focus and deflection Cutaway rendering of a color CRT: 1. ... The Selectron was an early form of computer memory developed by RCA. Development started in 1946 with a planned production of 200 by the end of the year, but production problems meant that they were still not available by the middle of 1948. ... Structure of a vacuum tube diode Structure of a vacuum tube triode In electronics, a vacuum tube, electron tube, or (outside North America) thermionic valve or just valve, is a device used to amplify, switch or modify a signal by controlling the movement of electrons in an evacuated space. ...


Delay line memory used sound waves in a substance such as mercury to store information. Delay line memory was dynamic volatile, cycle sequential read/write storage, and was used for primary storage. Mercury memory of UNIVAC I (1951) Delay line memory was a form of computer memory used on some of the earliest digital computers, such as the EDSAC and UNIVAC I. The basic concept of the delay line originated with World War II radar research, specifically to reduce clutter from reflections... This article is about compression waves. ... General Name, Symbol, Number mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12, 6, d Appearance silvery Standard atomic weight 200. ...


Other proposed methods

Phase-change memory uses different mechanical phases of phase change material to store information, and reads the information by observing the varying electric resistance of the material. Phase-change memory would be non-volatile, random access read/write storage, and might be used for primary, secondary and off-line storage. Phase-change memory (also known as PCM, PRAM, Ovonic Unified Memory and Chalcogenide RAM [C-RAM]) is a type of non-volatile computer memory. ... A Phase Change Material (PCM) is a substance with a high heat of fusion which, melting and solidifying at certain temperatures, is capable of storing or releasing large amounts of energy. ... Electrical resistance is a measure of the degree to which an electrical component opposes the passage of current. ...


Holographic storage stores information optically inside crystals or photopolymers. Holographic storage can utilize the whole volume of the storage medium, unlike optical disc storage which is limited to a small number of surface layers. Holographic storage would be non-volatile, sequential access, and either write once or read/write storage. It might be used for secondary and off-line storage. Holographic memory is a technique that can store information at high density inside crystals or photopolymers. ... Quartz crystal Synthetic bismuth hopper crystal Insulin crystals Gallium, a metal that easily forms large single crystals A huge monocrystal of potassium dihydrogen phosphate grown from solution by Saint-Gobain for the megajoule laser of CEA. In chemistry and mineralogy, a crystal is a solid in which the constituent atoms... A photopolymer is a polymer which is cured by exposure to light, often in the ultraviolet spectum. ...


Molecular memory stores information in polymers that can store electric charge. Molecular memory might be especially suited for primary storage. Molecular memory is a type of experimental data storage technology which hopes to supplant DRAM memory as the lowest cost technology for high-speed computer memory. ... A polymer (from Greek: πολυ, polu, many; and μέρος, meros, part) is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ...


Primary storage topics

Memory management is the act of managing computer memory. ... How virtual memory maps to physical memory Virtual memory is an addressing scheme implemented in hardware and software that allows non-contiguous memory to be addressed as if it were contiguous. ... It has been suggested that this article or section be merged with Primary storage. ... It has been suggested that this article or section be merged with Dynamic memory allocation. ... Dynamic Memory, often called heap memory, is one of the types of memory allocation that happens inside of a computer program. ... In computer science, a memory leak is a particular kind of unintentional memory consumption by a computer program where the program fails to release memory when no longer needed. ... Memory protection is a system that prevents one process from corrupting the memory of another process running on the same computer at the same time. ... A USB flash drive. ... A flash SSD in standard 2. ... Dynamic random access memory (DRAM) is a type of random access memory that stores each bit of data in a separate capacitor within an integrated circuit. ... Static random access memory (SRAM) is a type of semiconductor memory. ...

Secondary, tertiary and off-line storage topics

This is a list of file formats organized by type, as can be found on computers. ... A wait state is a delay experienced by a computer processor when accessing external memory or another device that is slow to respond. ... Write protection, (also known as record protection) is a mechanism that prevents erasure of valuable data by the accidental recording or storing of new data. ... Virtual Tape Library (VTL) is a data storage virtualization technology used typically for archival storage purposes. ...

Data storage conferences

Storage Networking World (commonly called SNW) is a business conference for data storage professionals in the United States. ... Storage World Conference (sometimes called SWC) is a business conference for data storage professionals in the United States. ...

References

  • Estimates of the quantities of data contained by the various media
  • Who Is Smarter, You Or Your Computer?

  Results from FactBites:
 
Computer History Museum - Events (339 words)
During the 1960's, most data storage systems used with mainframes and minicomputers were the ones specified by individual computer manufacturers.
Their leadership has made possible much of the computer industry's movement to more flexible interconnection of storage products and systems, combined with the enhanced reliability of RAID technology, and the ability to quickly utilize the annual improvements in disk and tape products.
The Computer History Museum Presents Speaker Series is an exclusive platform for open, passionate discussions for presenting the computing revolution and its impact on the human experience.
Computer storage - Wikipedia, the free encyclopedia (2615 words)
The fundamental components of a general-purpose computer are arithmetic and logic unit, control circuitry, storage space, and input/output devices.
The relevant unit of measurement is typically nanosecond for primary storage, millisecond for secondary storage, and second for tertiary storage.
In early computers, magnetic storage was also used for primary storage in a form of magnetic drum, or core memory, core rope memory, thin film memory, twistor memory or bubble memory.
  More results at FactBites »

 
 

COMMENTARY     

Hal Jordan
15th September 2010
Wow thanks so much for all of the information. I had a lot of questions about how storage works and you've answered almost all of them. I'm glad I didn't have to go to various different pages and sites to collect all of this information. http://www.opendrive.com

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