HOME TheInfoList.com
Providing Lists of Related Topics to Help You Find Great Stuff

picture info

Twistor Memory
Twistor is a form of computer memory formed by wrapping magnetic tape around a current-carrying wire. Operationally, twistor was very similar to core memory. Twistor could also be used to make ROM memories, including a re-programmable form known as piggyback twistor. Both forms were able to be manufactured using automated processes, which was expected to lead to much lower production costs than core-based systems. Introduced by Bell Labs
Bell Labs
in 1957, the first commercial use was in their 1ESS switch
1ESS switch
which went into operation in 1965. Twistor was used only briefly in the late 1960s and early 1970s, when semiconductor memory devices replaced almost all earlier memory systems
[...More...]

picture info

Bit
The bit (a portmanteau of binary digit)[1] is a basic unit of information used in computing and digital communications. A binary digit can have only one of two values, and may be physically represented with a two-state device. These state values are most commonly represented as either a 0or1. The two values of a binary digit can also be interpreted as logical values (true/false, yes/no), algebraic signs (+/−), activation states (on/off), or any other two-valued attribute. The correspondence between these values and the physical states of the underlying storage or device is a matter of convention, and different assignments may be used even within the same device or program
[...More...]

picture info

Magnetic Hysteresis
Magnetic hysteresis
Magnetic hysteresis
occurs when an external magnetic field is applied to a ferromagnet such as iron and the atomic dipoles align themselves with it. Even when the field is removed, part of the alignment will be retained: the material has become magnetized. Once magnetized, the magnet will stay magnetized indefinitely. To demagnetize it requires heat or a magnetic field in the opposite direction. This is the effect that provides the element of memory in a hard disk drive. The relationship between field strength H and magnetization M is not linear in such materials. If a magnet is demagnetized (H=M=0) and the relationship between H and M is plotted for increasing levels of field strength, M follows the initial magnetization curve. This curve increases rapidly at first and then approaches an asymptote called magnetic saturation. If the magnetic field is now reduced monotonically, M follows a different curve
[...More...]

picture info

Angle
2D anglesRight Interior Exterior2D angle pairsAdjacent Vertical Complementary Supplementary Transversal3D anglesDihedralAn angle formed by two rays emanating from a vertex.In planar geometry, an angle is the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle.[1] Angles formed by two rays lie in a plane, but this plane does not have to be a Euclidean plane. Angles are also formed by the intersection of two planes in Euclidean and other spaces. These are called dihedral angles. Angles formed by the intersection of two curves in a plane are defined as the angle determined by the tangent rays at the point of intersection. Similar statements hold in space, for example, the spherical angle formed by two great circles on a sphere is the dihedral angle between the planes determined by the great circles. Angle
Angle
is also used to designate the measure of an angle or of a rotation
[...More...]

picture info

Magnet
A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, and attracts or repels other magnets. The overall strength of a magnet is measured by its magnetic moment or, alternatively, the total magnetic flux it produces. The local strength of magnetism in a material is measured by its magnetization. A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. An everyday example is a refrigerator magnet used to hold notes on a refrigerator door. Materials that can be magnetized, which are also the ones that are strongly attracted to a magnet, are called ferromagnetic (or ferrimagnetic). These include iron, nickel, cobalt, some alloys of rare-earth metals, and some naturally occurring minerals such as lodestone
[...More...]

picture info

1ESS Switch
The Number One Electronic Switching System (1ESS) was the first large-scale stored program control (SPC) telephone exchange or electronic switching system in the Bell System
[...More...]

picture info

Bell Labs
Nokia
Nokia
Bell Labs
Bell Labs
(formerly named AT&T Bell Laboratories, Bell Telephone
Telephone
Laboratories and Bell Labs) is an American research and scientific development company, owned by Finnish company Nokia. Its headquarters are located in Murray Hill, New Jersey, in addition to other laboratories around the rest of the United States
United States
and in other countries. The historic laboratory originated in the late 19th century as the Volta Laboratory and Bureau
Volta Laboratory and Bureau
created by Alexander Graham Bell
[...More...]

Mellon Optical Memory
Mellon optical memory was an early form of computer memory invented at the Mellon Institute
Mellon Institute
(today part of Carnegie Mellon University) in 1951.[1][2] The device used a combination of photoemissive and phosphorescent materials to produce a "light loop" between two surfaces. The presence or lack of light, detected by a photocell, represented a one or zero. Although promising, the system was rendered obsolete with the introduction of core memory in the early 1950s. It appears that the system was never used in production.Contents1 Description1.1 Writing 1.2 Reading2 ReferencesDescription[edit] The main memory element of the Mellon device consisted of a very large (television sized) square vacuum tube consisting of two slightly separated flat glass plates. The inner side of one of the plates was coated with a photoemissive material that released electrons when struck by light
[...More...]

picture info

Disk Pack
Disk packs and disk cartridges were early forms of removable media for computer data storage, introduced in the 1960s.Contents1 Disk pack 2 Disk cartridge 3 Alignment 4 References 5 See alsoDisk pack[edit] Disk pack
Disk pack
manufactured by Nashua, USA, without its protective cover. A 3.5" modern hard drive is shown for comparison.A Disk pack
Disk pack
is a layered grouping of hard disk platters (circular, rigid discs coated with a magnetic data storage surface). A disk pack is the core component of a hard disk drive. In modern hard disks, the disk pack is permanently sealed inside the drive. In many early hard disks, the disk pack was a removable unit, and would be supplied with a protective canister featuring a lifting handle. The protective cover consisted of two parts, a clear plastic shell, with a handle in the center, that enclosed the top and sides of the disks and a separate bottom that completed the sealed package
[...More...]

picture info

Dekatron
In electronics, a Dekatron
Dekatron
(or Decatron, or generically three-phase gas counting tube or glow-transfer counting tube or cold cathode tube) is a gas-filled decade counting tube. Dekatrons were used in computers, calculators and other counting-related products during the 1950s and 1960s. "Dekatron," now a generic trademark, was the brand name used by Ericsson Telephones Limited (ETL), of Beeston, Nottingham (not to be confused with the Swedish TelefonAB Ericsson
Ericsson
of Stockholm).A dekatron in operation.The dekatron was useful for computing, calculating and frequency-dividing purposes because one complete revolution of the neon dot in a dekatron means 10 pulses on the guide electrode(s), and a signal can be derived from one of the ten cathodes in a dekatron to send a pulse, possibly for another counting stage
[...More...]

Paper Data Storage
Paper
Paper
data storage refers to the use of paper as a data storage device. This includes writing, illustrating, and the use of data that can be interpreted by a machine or is the result of the functioning of a machine. A defining feature of paper data storage is the ability of humans to produce it with only simple tools and interpret it visually. Though this is now mostly obsolete, paper was once also an important form of computer data storage.Contents1 History 2 Limits 3 See also 4 References 5 External linksHistory[edit] Before paper was used for storing data, it had been used in several applications for storing instructions to specify a machine's operation. The earliest use of paper to store instructions for a machine was the work of Basile Bouchon
Basile Bouchon
who, in 1725, used punched paper rolls to control textile looms. This technology was later developed into the wildly successful Jacquard loom
[...More...]

picture info

Optical Disc
In computing and optical disc recording technologies, an optical disc (OD) is a flat, usually circular disc which encodes binary data (bits) in the form of pits (binary value of 0 or off, due to lack of reflection when read) and lands (binary value of 1 or on, due to a reflection when read) on a special material (often aluminium[1] ) on one of its flat surfaces. The encoding material sits atop a thicker substrate (usually polycarbonate) which makes up the bulk of the disc and forms a dust defocusing layer. The encoding pattern follows a continuous, spiral path covering the entire disc surface and extending from the innermost track to the outermost track
[...More...]

picture info

Magnetic Tape
Magnetic tape
Magnetic tape
is a medium for magnetic recording, made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany
Germany
in 1928, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders. A device that stores computer data on magnetic tape is known as a tape drive. Magnetic tape
Magnetic tape
revolutionized broadcast and recording. It allowed radio, which had always been broadcast live, to be recorded for later or repeated airing. It allowed gramophone records to be recorded in multiple parts, which were then mixed and edited with tolerable loss in quality
[...More...]

picture info

Core Rope Memory
Core rope memory
Core rope memory
is a form of read-only memory (ROM) for computers, first used in the 1960s by early NASA Mars space probes and then in the Apollo Guidance Computer
Computer
(AGC) designed and programmed by the Massachusetts Institute of Technology
Massachusetts Institute of Technology
(MIT) Instrumentation Lab and built by Raytheon. Contrary to ordinary coincident-current magnetic-core memory, which was used for random access memory (RAM) at the time, the ferrite cores in a core rope are just used as transformers. The signal from a word line wire passing through a given core is coupled to the bit line wire and interpreted as a binary "one", while a word line wire that bypasses the core is not coupled to the bit line wire and is read as a "zero"
[...More...]

picture info

Hard Disk Drive
A hard disk drive (HDD), hard disk, hard drive or fixed disk[b] is a data storage device that uses magnetic storage to store and retrieve digital information using one or more rigid rapidly rotating disks (platters) coated with magnetic material. The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces.[2] Data is accessed in a random-access manner, meaning that individual blocks of data can be stored or retrieved in any order and not only sequentially. HDDs are a type of non-volatile storage, retaining stored data even when powered off.[3][4][5] Introduced by IBM
IBM
in 1956,[6] HDDs became the dominant secondary storage device for general-purpose computers by the early 1960s. Continuously improved, HDDs have maintained this position into the modern era of servers and personal computers
[...More...]

Mask ROM
Mask ROM (MROM) is a type of read-only memory (ROM) whose contents are programmed by the integrated circuit manufacturer (rather than by the user). The terminology mask comes from integrated circuit fabrication, where regions of the chip are masked off during the process of photolithography. It is common practice to use rewritable non-volatile memory – such as UV- EPROM
EPROM
or E EPROM
EPROM
– for the development phase of a project, and to switch to mask ROM when the code has been finalized. For example, Atmel
Atmel
microcontrollers come in both E EPROM
EPROM
and mask ROM formats. The main advantage of mask ROM is its cost. Per bit, mask ROM is more compact than any other kind of semiconductor memory
[...More...]

.