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Bit Density
Density is a measure of the quantity of information bits that can be stored on a given physical space of a computer storage medium. There are three types of density: length (''linear density'') of track, area of the surface (''areal density''), or in a given volume (''volumetric density''). Generally, higher density is more desirable, for it allows more data to be stored in the same physical space. Density therefore has a direct relationship to storage capacity of a given medium. Density also generally affects the performance within a particular medium, as well as price. Storage device classes Solid state media Solid state drives use flash memory to store non-volatile media. They are the latest form of mass produced storage and rival magnetic disk media. Solid state media data is saved to a pool of NAND flash. NAND itself is made up of what are called floating gate transistors. Unlike the transistor designs used in DRAM, which must be refreshed multiple times per second, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space
Space is a three-dimensional continuum containing positions and directions. In classical physics, physical space is often conceived in three linear dimensions. Modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum known as '' spacetime''. The concept of space is considered to be of fundamental importance to an understanding of the physical universe. However, disagreement continues between philosophers over whether it is itself an entity, a relationship between entities, or part of a conceptual framework. In the 19th and 20th centuries mathematicians began to examine geometries that are non-Euclidean, in which space is conceived as '' curved'', rather than '' flat'', as in the Euclidean space. According to Albert Einstein's theory of general relativity, space around gravitational fields deviates from Euclidean space. Experimental tests of general relativity have confirmed that non-Euclidean geometries provide a bet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heat-assisted Magnetic Recording
Heat-assisted magnetic recording (HAMR) (pronounced "''hammer''") is a magnetic storage technology for greatly increasing the amount of data that can be stored on a magnetic device such as a hard disk drive by temporarily heating the disk material during writing, which makes it much more receptive to magnetic effects and allows writing to much smaller regions (and much higher levels of data on a disk). The technology was initially seen as extremely difficult to achieve, with doubts expressed about its feasibility in 2013. The regions being written must be heated in a tiny area – small enough that diffraction prevents the use of normal laser focused heating – and requires a heating, writing and cooling cycle of less than 1 nanosecond, while also controlling the effects of repeated spot-heating on the drive platters, the drive-to-head contact, and the adjacent magnetic data which must not be affected. These challenges required the development of nano-scale surface plasmons (surf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exabytes
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit of memory in many computer architectures. To disambiguate arbitrarily sized bytes from the common 8-bit definition, network protocol documents such as the Internet Protocol () refer to an 8-bit byte as an octet. Those bits in an octet are usually counted with numbering from 0 to 7 or 7 to 0 depending on the bit endianness. The size of the byte has historically been hardware-dependent and no definitive standards existed that mandated the size. Sizes from 1 to 48 bits have been used. The six-bit character code was an often-used implementation in early encoding systems, and computers using six-bit and nine-bit bytes were common in the 1960s. These systems often had memory words of 12, 18, 24, 30, 36, 48, or 60 bits, corresponding to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronic Quantum Holography
Electronic quantum holography (also known as quantum holographic data storage) is an information storage technology which can encode and read out data at unprecedented density storing as much as 35 bits per electron. Research In 2009, Stanford University's Department of Physics set a new world record for the smallest writing using a scanning tunneling microscope and electron waves to write the initials "SU" at 0.3 nanometers, surpassing the previous record set by IBM in 1989 using xenon atoms. This achievement also set a record for the density of information. Before this technology was invented the density of information had not exceeded one bit per atom. Researchers of electronic quantum holography however were able to push the limit to 35 bits per electron or 20 bits nm−2. Technology A copper chip is placed in a microscope and cleaned. Carbon monoxide molecules are then placed on the surface and moved around. When the electrons in copper interact with the carbon monoxide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gigabyte
The gigabyte () is a multiple of the unit byte for digital information. The SI prefix, prefix ''giga-, giga'' means 109 in the International System of Units (SI). Therefore, one gigabyte is one billion bytes. The unit symbol for the gigabyte is GB. This definition is used in all contexts of science (especially data science), engineering, business, and many areas of computing, including storage capacities of hard disk drive, hard drives, solid-state drives, and magnetic-tape data storage, tapes, as well as data transmission speeds. The term is also used in some fields of computer science and information technology to denote (10243 or 230) bytes, however, particularly for sizes of random-access memory, RAM. Thus, some usage of ''gigabyte'' has been ambiguous. To resolve this difficulty, IEC 80000-13 clarifies that a ''gigabyte'' (GB) is 109 bytes and specifies the term ''gibibyte'' (GiB) to denote 230 bytes. These differences are still readily seen, for example, when a 400 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holographic Storage
Holographic data storage is a potential technology in the area of high-capacity data storage. While magnetic and optical data storage devices rely on individual bits being stored as distinct magnetic or optical changes on the surface of the recording medium, holographic data storage records information throughout the volume of the medium and is capable of recording multiple images in the same area utilizing light at different angles. Additionally, whereas magnetic and optical data storage records information a bit at a time in a linear fashion, holographic storage is capable of recording and reading millions of bits in parallel, enabling data transfer rates greater than those attained by traditional optical storage. Recording data Holographic data storage contains information using an optical interference pattern within a thick, photosensitive optical material. Light from a single laser beam is divided into two, or more, separate optical patterns of dark and light pixels. By ad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Millipede Memory
Millipede memory is a form of non-volatile computer memory. It promised a data density of more than 1 terabit per square inch (1 gigabit per square millimeter), which is about the limit of the perpendicular recording hard drives. Millipede storage technology was pursued as a potential replacement for magnetic recording in hard drives and a means of reducing the physical size of the technology to that of flash media. IBM demonstrated a prototype millipede storage device at CeBIT 2005, and was trying to make the technology commercially available by the end of 2007. However, because of concurrent advances in competing storage technologies, no commercial product has been made available since then. Technology Basic concept The main memory of modern computers is constructed from one of a number of DRAM-related devices. DRAM basically consists of a series of capacitors, which store data in terms of the presence or absence of electrical charge. Each capacitor and its associated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linear Tape-Open
Linear Tape-Open (LTO), also known as the LTO Ultrium format, is a magnetic tape data storage technology used for backup, data archiving, and data transfer. It was originally developed in the late 1990s as an open standards alternative to the proprietary magnetic tape formats available at the time. Upon introduction, LTO rapidly defined the ''super tape'' market segment and has consistently been the best-selling super tape format. The latest generation as of 2025, LTO-10, can hold in one cartridge, or with industry-standard 2.5:1 compression. Cartridges contain hundreds of meters of half-inch (12.65 mm) wide tape media wound onto a single reel. Mechanisms (a.k.a. tape drives, streamers) extract the tape from the cartridge and spool it up on a second reel in the mechanism, reading or writing data as the tape moves between reels. Robotic Tape library, libraries exist that can hold hundreds or thousands of LTO cartridges and dozens of mechanisms. The original version of LTO U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UNISERVO
The UNISERVO tape drive was the primary I/O device on the UNIVAC I computer. It was the first tape drive for a commercially sold computer. The UNISERVO used metal tape: a thin strip of nickel-plated phosphor bronze (called Vicalloy) 1200 feet long. These metal tapes and reels were very heavy with a combined weight of 25lbs. Data was recorded in eight channels on the tape (six for the data value, one parity channel for error checking, and one timing channel) at a density of 128 bits per inch. The tape could be moved at 100 inches per second, giving a nominal transfer rate of 12,800 characters per second. Data were recorded in fixed size blocks of 60 words of 12 characters each. Making allowance for the empty space between tape blocks, the actual transfer rate was around 7,200 characters per second. The UNISERVO supported both forward and backward modes on read or write operation. This offered significant advantages in data sorting and merging applications. The data transfers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Univac
UNIVAC (Universal Automatic Computer) was a line of electronic digital stored-program computers starting with the products of the Eckert–Mauchly Computer Corporation. Later the name was applied to a division of the Remington Rand company and successor organizations. The BINAC, built by the Eckert–Mauchly Computer Corporation, was the first general-purpose computer for commercial use, but it was not a success. The last UNIVAC-badged computer was produced in 1986. History and structure J. Presper Eckert and John Mauchly built the ENIAC (Electronic Numerical Integrator and Computer) at the University of Pennsylvania's Moore School of Electrical Engineering between 1943 and 1946. A 1946 patent rights dispute with the university led Eckert and Mauchly to depart the Moore School to form the Electronic Control Company, later renamed Eckert–Mauchly Computer Corporation (EMCC), based in Philadelphia, Pennsylvania. That company first built a computer called BINAC (BINary Automat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blu-ray
Blu-ray (Blu-ray Disc or BD) is a digital optical disc data storage format designed to supersede the DVD format. It was invented and developed in 2005 and released worldwide on June 20, 2006, capable of storing several hours of high-definition video ( HDTV 720p and 1080p). The main application of Blu-ray is as a medium for video material such as feature films and for the physical distribution of video games for the PlayStation 3, PlayStation 4, PlayStation 5, Xbox One, and Xbox Series X. The name refers to the blue laser used to read the disc, which allows information to be stored at a greater density than is possible with the longer-wavelength red laser used for DVDs, resulting in an increased capacity. The polycarbonate disc is in diameter and thick, the same size as DVDs and CDs. Conventional (or "pre-BDXL") Blu-ray discs contain 25 GB per layer, with dual-layer discs (50GB) being the industry standard for feature-length video discs. Triple-layer discs (10 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
