FACTOID # 4: Just 1% of the houses in Nevada were built before 1939.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Delay line memory
Mercury memory of UNIVAC I (1951)
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. Image File history File links Mercury_memory. ... Image File history File links Mercury_memory. ... UNIVAC I Central Complex, containing the central processor and main memory unit. ... The terms storage (U.K.) or memory (U.S.) refer to the parts of a digital computer that retain physical state (data) for some interval of time, possibly even after electrical power to the computer is turned off. ... A digital system is one that uses discrete values (often electrical voltages), especially those representable as binary numbers, or non-numeric symbols such as letters or icons, for input, processing, transmission, storage, or display, rather than a continuous spectrum of values (ie, as in an analog system). ... This article is about the machine. ... EDSAC EDSAC (Electronic Delay Storage Automatic Calculator) was an early British computer (one of the first computers to be created). ... UNIVAC I Central Complex, containing the central processor and main memory unit. ...

Contents

Early examples

The basic concept of the delay line originated with World War II radar research, as a system to reduce clutter from reflections from the ground and other "fixed" objects. Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000... For other uses, see Radar (disambiguation). ...


A radar system consists largely of an antenna, a transmitter, a receiver, and a display of some sort. The antenna is connected to the transmitter, which sends out a brief pulse of radio energy before being disconnected again. The antenna is then connected to the receiver, which amplifies any reflected signals, and sends them to the display. Objects further from the radar return echos later in time than those located closer to the radar, which the display indicates visually. Modern radar systems typically use some sort of raster scan display to produce a map-like image. ...


Objects at a fixed distance from the antenna always return a signal after the same delay. In order to filter these out, two pulses were compared, and returns with common timing are removed. To do this, the signal being sent from the receiver to the display was split in two, with one path leading directly to the display, and the second leading to a delay unit. The delay was carefully tuned to delay the signals some multiple of the time between pulses (the pulse repetition frequency), that way the delayed signal from an earlier pulse would exit the delay unit at the same time as a newer pulse was being received from the antenna. One of the signals was then inverted, typically the one from the delay, and the two signals were then mixed and sent to the display. The result was that any signal that was at the same location it was in the past was nullified by the inverted signal from a previous pulse, leaving only the moving objects on the display. Pulse Repetition Frequency (PRF) is the number of pulses transmitted per second by the radar. ...


Several different types of delay systems were invented for this purpose, with one common principle being that the information was stored acoustically in a medium. MIT experimented with a number of systems including glass, quartz, steel and lead. The Japanese deployed a system consisting of a quartz element with a powdered glass coating that reduced surface waves that interfered with proper reception. The Naval Research Laboratories used steel rods wrapped into a helix, but this was useful only for low frequencies under 1 MHz. Raytheon used a magnesium alloy originally developed for making bells.[1] Acoustics is a branch of physics and is the study of sound (mechanical waves in gases, liquids, and solids). ... Mapúa Institute of Technology (MIT, MapúaTech or simply Mapúa) is a private, non-sectarian, Filipino tertiary institute located in Intramuros, Manila. ... // In physics, a surface wave can refer to a mechanical wave that propagates along the interface between differing media, usually two fluids with different densities. ...


Acoustic delay lines

Mercury delay lines

The most practical such system was developed by J. Presper Eckert at the University of Pennsylvania's Moore School of Electrical Engineering. His solution used a column of mercury with piezo crystal transducers (a combination of speaker and microphone) at either end. Signals from the radar amplifier were sent to the piezo at one end of the tube, which would cause the transducer to pulse and generate a small wave in the mercury. The wave would quickly travel to the far end of the tube, where it would be read back out by the other piezo, inverted, and sent to the display. Careful mechanical arrangement was needed to ensure the delay time matched the inter-pulse timing of the particular radar being used. Eckert and Mauchly examine a printout of ENIAC results in a newsreel from February 1946. ... This article is about the private Ivy League university in Philadelphia. ... The Moore School of Electrical Engineering at the University of Pennsylvania came into existence as a result of an endowment from Alfred Fitler Moore on June 4th, 1923. ... General Name, Symbol, Number mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12, 6, d Appearance silvery Standard atomic weight 200. ... Piezoelectricity is the ability of some materials (notably crystals and certain ceramics) to generate an electric potential[1] in response to applied mechanical stress. ... A transducer is a device, usually electrical or electronic, that converts one type of energy to another. ...


For a computer application the timing was still critical, but for a different reason. Conventional computers have a natural "cycle time" needed to complete an operation, the start and end of which typically consist of reading or writing memory. Thus the delay lines had to be timed such that the pulses would arrive at the receiver just as the computer was ready to read it. Typically many pulses would be "in flight" through the delay, and the computer would count the pulses by comparing to a master clock to find the particular bit it was looking for.


Mercury was used because the acoustic impedance of mercury is almost exactly the same as that of the piezoelectric quartz crystals; this minimized the energy loss and the echoes when the signal was transmitted from crystal to medium and back again. The high speed of sound in mercury (1450 m/s) meant that the time needed to wait for a pulse to arrive at the receiving end was less than it would have been with a slower medium, such as air, but it also meant that the total number of pulses that could be stored in any reasonably sized column of mercury was limited. Other technical drawbacks of mercury included its weight, its cost, and its toxicity. Moreover, to get the acoustic impedances to match as closely as possible, the mercury had to be kept at a temperature of 40 degrees Celsius, which made servicing the tubes hot and uncomfortable work. The acoustic impedance Z (or sound impedance) is a frequency f dependent parameter and is very useful, for example, for describing the behaviour of musical wind instruments. ... Sound is a vibration that travels through an elastic medium as a wave. ...


A considerable amount of engineering was needed to maintain a "clean" signal inside the tube. Large transducers were used to generate a very tight "beam" of sound that would not touch the walls of the tube, and care had to be taken to eliminate reflections off the far end of the tubes. The tightness of the beam then required considerable tuning to make sure the two piezos were pointed directly at each other. Since the speed of sound changes with temperature (because of the change in density with temperature) the tubes were heated in large ovens to keep them at a precise temperature. Other systems instead adjusted the computer clock rate according to the ambient temperature, to achieve the same effect.


EDSAC, the first practical stored-program digital computer, began operation with 512 35-bit words of memory, stored in 32 delay lines holding 576 bits each (a 36th bit was added to every word as a start/stop indicator). In the UNIVAC I this was reduced somewhat, each column stored 120 bits (although the term "bit" was not in popular use at the time), requiring seven large memory units with 18 columns each to make up a 1000-word store. Combined with their support circuitry and amplifiers, the memory subsystem formed its own walk-in room. The average access time was about 222 microseconds, which was considerably faster than the mechanical systems used on earlier computers. EDSAC EDSAC (Electronic Delay Storage Automatic Calculator) was an early British computer (one of the first computers to be created). ... The so-called von Neumann architecture is a model for a computing machine that uses a single storage structure to hold both the set of instructions on how to perform the computation and the data required or generated by the computation. ... ... A word is a unit of language that carries meaning and consists of one or more morphemes which are linked more or less tightly together, and has a phonetical value. ... UNIVAC I Central Complex, containing the central processor and main memory unit. ... This article is about the unit of information. ... Generally, an amplifier is any device that will use a small amount of energy to control a larger amount of energy. ... A room, in architecture, is any distinguishable space within a structure. ... To help compare orders of magnitude of different times this page lists times between 10−6 seconds and 10−5 seconds (1. ...


Magnetostrictive delay lines

A later version of the delay line used metal wires as the storage medium. Transducers were built by applying the magnetostrictive effect; small pieces of a magnetostrictive material, typically nickel, were attached to either side of the end of the wire, inside an electromagnet. When bits from the computer entered the magnets the nickel would contract or expand (based on the polarity) and twist the end of the wire. The resulting torsional wave would then move down the wire just as the sound wave did down the mercury column. In most cases the entire wire was made of the same material. It has been suggested that solid wire be merged into this article or section. ... Magnetostriction is a property of ferromagnetic materials that causes them to change their shape when subjected to a magnetic field. ... General Name, symbol, number nickel, Ni, 28 Chemical series transition metals Group, period, block 10, 4, d Appearance lustrous, metallic and silvery with a gold tinge Standard atomic weight 58. ...


Unlike the compressive wave, however, the torsional waves are considerably more resistant to problems caused by mechanical imperfections, so much so that the wires could be wound into a loose coil and pinned to a board. Due to their ability to be coiled, the wire-based systems could be built as "long" as needed, and tended to hold considerably more data per unit; 1k units were typical on a board only 1 foot square. Of course this also meant that the time needed to find a particular bit was somewhat longer as it traveled through the wire, and access times on the order of 500 microseconds were typical. Look up torsion in Wiktionary, the free dictionary. ... A kilobit is a unit of information storage, abbreviated kbit or sometimes kb. ...


Delay line memory was far less expensive and far more reliable per bit than flip-flops made from tubes, and yet far faster than a latching relay. It was used right into the late 1960s, notably on British commercial machines like the LEO I and various Ferranti machines. They were also used very successfully in several models of early desktop electronic calculator, including the Friden EC130 (1964) and EC132, the Olivetti Programma 101 desktop programmable calculator introduced in 1965, and the Litton Monroe Epic 2000 and 3000 programmable calculators of 1967. In digital circuits, the flip-flop, latch, or bistable multivibrator is an electronic circuit which has two stable states and thereby is capable of serving as one bit of memory. ... 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. ... Automotive style miniature relay A relay is an electrical switch that opens and closes under the control of another electrical circuit. ... The 1960s decade refers to the years from January 1, 1960 to December 31, 1969, inclusive. ... Pope Leo I Emperor Leo I LEO I, a computer Leo I (dwarf galaxy) which is a galaxy that orbits the Milky Way Galaxy. ... Ferranti or Ferranti International plc by the time of its collapse, was a major UK electrical engineering and equipment firm, known primarily for defence electronics and power grid systems. ... A modern basic arithmetic calculator A calculator is a device for performing numerical calculations. ... 1964 (MCMLXIV) was a leap year starting on Wednesday (the link is to a full 1964 calendar). ... Olivetti Lettera 22, 1950 Ing. ... Programmable calculators are calculators capable of being programmed much like a computer. ... Year 1965 (MCMLXV) was a common year starting on Friday (link will display full calendar) of the 1965 Gregorian calendar. ... The Monroe EPIC was a programmable calculator come on the market in the 1960s. ... Wikipedia does not yet have an article with this exact name. ... Year 1967 (MCMLXVII) was a common year starting on Sunday (link will display full calendar) of the 1967 Gregorian calendar. ...


Piezoelectric delay lines

An ultrasonic delay line from a Colour-TV; it dealyes the colour signal for 64µsManufacturer: VEB ELFEMA Mittweida (GDR) in 1980
An ultrasonic delay line from a Colour-TV; it dealyes the colour signal for 64µs
Manufacturer: VEB ELFEMA Mittweida (GDR) in 1980

A similar solution to the magnetostrictive solution was to use delay lines made entirely of a piezo material, typically quartz. Current fed into one end of the crystal would generate a compressive wave that would flow to the other end where it could be read out. In effect, piezoelectric delays simply replaced the mercury and transducers of a conventional mercury delay line with a single unit combining both. However these solutions were fairly rare; building crystals of the required quality in large sizes was not easy, limiting them to small sizes, and thus small amounts of data storage. Image File history File links Size of this preview: 597 × 599 pixelsFull resolution (886 × 889 pixel, file size: 83 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Image File history File links Size of this preview: 597 × 599 pixelsFull resolution (886 × 889 pixel, file size: 83 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Disambiguation Page Global Depositary Receipt East Germany ...


A better and wide-spreaded solution was to use piezoelectric transducers only at the ends of the acoustic wave path, which is guided in a quartz glass plate. The path can be folded by reflections at the edges of the plate. Those delay lines were used for delaying the colour signal in TV-Sets for one picture line (64µs in the european PAL- and SECAM system) to get all the colour information together at the same time from a difference signal, which consists of only a part of the full colour signal and is alternating each line.


Electric delay lines

Electric delay line (450ns), consisting of enamelled copper wire, wounded around a metal tube
Electric delay line (450ns), consisting of enamelled copper wire, wounded around a metal tube

Electric delay lines are used for shorter delay times (ns to several µs). They consist of a long electric line or made of discrete inductors and capacitors, which are arranged in a chain.
To shorten the total length of the line it can be wounded around a metallic tube, getting some more capacitance against ground and also more inductance due to the wire wounds, which are laying close together. Image File history File links Size of this preview: 800 × 582 pixelsFull resolution (952 × 693 pixel, file size: 70 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Image File history File links Size of this preview: 800 × 582 pixelsFull resolution (952 × 693 pixel, file size: 70 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ...


Other examples are:

Another way to create a delay time is to implement a delay line in an integrated circuit storage device. This can be done digitally or in a discrete analogue method. The analogue one uses charge coupled devices (CCD), which transport a stored electric charge stepwise from one end to the other. Both methods are bandwidth limited at the upper end to the half of the clock frequency, which determines the steps of transportation. Cross-section of microstrip geometry. ... In biology, antenna (plural: antennae) refers to the sensing organs of several arthropods. ... A cavity magnetron is a high-powered vacuum tube that generates coherent microwaves. ... Reflex klystron Type 2K25 or 723 A/B. The threaded adjustment rod on the right side allows the position of the reflector to be adjusted (by compressing the reflex cavity), and thus the natural resonant frequency of the device. ... A TWTA or travelling-wave tube amplifier is an electronic device used to produce high-power radiofrequency signals. ... Electromagnetic radiation or EM radiation is a combination (cross product) of oscillating electric and magnetic fields perpendicular to each other, moving through space as a wave, effectively transporting energy and momentum. ... An undulator is a device from high-energy physics and usually part of a larger installation, a synchrotron. ... X-ray free electronic laser schema of operation A free electron laser, or FEL, is a laser that shares the same optical properties as conventional lasers such as emitting a beam consisting of coherent electromagnetic radiation which can reach high power, but which uses some very different operating principles to... 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. ... A storage device is a device used for storing something. ... A charge-coupled device (CCD), is an integrated circuit containing an array of linked, or coupled, capacitors. ...


References

  1. ^ J.P. Eckert, Jr., A Survey of Digital Computer Memory Systems, Proceedings of the IRE, October 1958

External links


  Results from FactBites:
 
Delay line memory - Wikipedia, the free encyclopedia (994 words)
Delay line memory was a form of computer memory used on some of the earliest digital computers, such as the EDSAC and UNIVAC I.
Thus the delay lines had to be timed such that the pulses would arrive at the receiver just as the computer was ready to read it.
Delay line memory was far less expensive and far more reliable per bit than flip-flops made from tubes, and yet far faster than a latching relay.
Delay line - Wikipedia, the free encyclopedia (321 words)
In electronics and derivative fields such as telecommunications, a delay line is rigorously defined as a single-input-channel device, in which the output channel state at a given instant, t, is the same as the input channel state at the instant t−n, where n is a number of time units, i.e.
A transmission line or equivalent device (such as an analog delay line) used to delay a signal.
In digital logic and digital signal processing, a delay line refers to a sequential logic element in which the output state at a given time n (in samples) is the same as the input was at the time n−L.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m